Colorado — Corporate Income / Franchise Tax

Colorado imposes a corporate income tax on each domestic C corporation, foreign C corporation, and combined group doing business in Colorado. The tax applies annually to the net income derived from sources within Colorado. All C corporations doing business in Colorado are required to file a Colorado corporate income tax return (Form DR 0112) with the Colorado Department of Revenue.

S corporations are not subject to Colorado corporate income tax; income from S corporations passes through to shareholders. Nonprofit corporations that file federal Form 990 and are exempt from filing a federal income tax return are also exempt from filing a Colorado income tax return. However, if a nonprofit has income from nonexempt functions subject to federal income tax (unrelated business taxable income), that income is subject to Colorado income tax and a return must be filed. Insurance companies subject to Colorado's insurance premium tax are exempt from Colorado income tax.

Source: Colorado Corporate Income Tax Guide | Corporate Income Tax Overview, Colorado General Assembly

Colorado follows the federal classification of partnerships and limited liability companies for income tax purposes and generally does not impose entity-level income tax on these pass-through entities. Instead, the partners or members are taxed on their distributive or pro rata shares of the entity's income, regardless of whether distributions are actually made.

General pass-through treatment: partners and members taxed, not the entity

Colorado statute provides that partners of a partnership—not the partnership entity itself—are subject to Colorado income tax. This is codified in Part 2 of Article 22 of Title 39, which covers "Partners and Partnerships." The structure mirrors the federal income tax treatment of partnerships under Subchapter K of the Internal Revenue Code.

Any group, organization, or business entity that is treated as a partnership for federal income tax purposes is treated as a partnership for Colorado income tax purposes, including any limited liability company classified as a partnership for federal income tax purposes. This conformity rule means that single-member LLCs disregarded for federal tax purposes are also disregarded for Colorado purposes, and multi-member LLCs treated as partnerships federally are treated as partnerships in Colorado.

An LLC classified as a partnership under the federal check-the-box regulations is not subject to Colorado corporate income tax at the entity level. Colorado defines "corporation" for corporate income tax purposes by reference to the federal definition and excludes entities classified as partnerships or S corporations under the Internal Revenue Code.

Publicly traded partnerships taxed as corporations under IRC § 7704

Colorado does not have a separate statutory provision specifically addressing publicly traded partnerships (PTPs). The Colorado Department of Revenue Corporate Income Tax Guide states that Colorado corporate income tax applies to "each domestic C corporation, foreign C corporation, and combined group doing business in Colorado" and that the tax "applies to all C corporations doing business in Colorado."

Because Colorado conforms to the federal definition of "corporation" and bases its corporate income tax on federal taxable income as the starting point, a publicly traded partnership that is classified as a corporation for federal income tax purposes under IRC § 7704(a)—because it does not qualify for the passive income exception under IRC § 7704(c)—is treated as a C corporation for Colorado purposes and is therefore subject to Colorado corporate income tax. Conversely, a PTP that qualifies for the IRC § 7704(c) exception and remains a partnership for federal purposes remains a pass-through entity for Colorado purposes and is not subject to entity-level Colorado income tax.

The Colorado Department of Revenue has not published guidance that separately addresses the treatment of publicly traded partnerships classified as corporations under IRC § 7704. Practitioners should confirm the entity's federal classification before determining Colorado filing obligations.

Optional entity-level taxation election: SALT Parity Act

For income tax years commencing on or after January 1, 2018, partnerships and S corporations may annually elect to be subject to Colorado income tax at the entity level under the SALT Parity Act, codified at C.R.S. §§ 39-22-340 to 39-22-347 and enacted by H.B. 21-1327 (amended by S.B. 22-124). This election was enacted to allow partners and shareholders to claim a federal deduction for state income taxes paid at the entity level, thereby avoiding the $10,000 federal cap on individual state and local tax deductions imposed by the Tax Cuts and Jobs Act of 2017. The election is available only in tax years when the federal IRC § 164 limitation on individual deductions for state and local taxes is in effect.

C.R.S. § 39-22-343 permits a partnership or S corporation to make the election annually on its Colorado Partnership and S Corporation Income Tax Return (Form DR 0106). For tax years commencing on or after January 1, 2022, the entity makes the election by checking the applicable box on Form DR 0106. The election is binding on all partners and shareholders for that tax year, except that the election does not apply to any partner that is a C corporation that is unitary with the partnership.

Under C.R.S. § 39-22-344, an electing partnership or S corporation is subject to Colorado income tax computed on the sum of (a) each resident partner's or shareholder's distributive or pro rata share of the entity's income (whether or not attributable to Colorado), and (b) each nonresident partner's or shareholder's distributive or pro rata share of the entity's income attributable to Colorado. Partners and shareholders in an electing pass-through entity are entitled to a credit under C.R.S. § 39-22-347 for their share of the entity-level tax paid, which offsets their individual Colorado income tax liability attributable to the pass-through entity's income.

The SALT Parity Act election is optional, not mandatory. Partnerships and S corporations that do not make the election continue to be treated as pass-through entities not subject to entity-level Colorado income tax, with their partners and shareholders reporting and paying Colorado income tax on their distributive shares.

Information reporting and withholding obligations

Even though partnerships and S corporations are generally not subject to entity-level income tax (absent a SALT Parity Act election), they must file an annual Colorado Partnership and S Corporation Income Tax Return (Form DR 0106) if they are doing business in Colorado or have Colorado-source income. The entity must also prepare and file Colorado K-1 forms (DR 0106K) for each partner or shareholder, reporting each member's distributive share of income, deductions, modifications, and credits.

For partnerships with nonresident partners, C.R.S. § 39-22-601(5) generally requires the partnership to either (a) file a nonresident agreement (Form DR 0107) under which the nonresident partner agrees to file a Colorado return and pay tax, or (b) pay Colorado income tax on behalf of the nonresident partner. C.R.S. § 39-22-601(5)(e), as amended by S.B. 22-124, provides that this withholding requirement does not apply to a partnership that makes the SALT Parity Act election under C.R.S. § 39-22-343.

Source: DR 0106 Partnership and S Corporation Income Tax Return, Colorado Department of Revenue | Income Tax Topics: SALT Parity Act, Colorado Department of Revenue | Corporate Income Tax Guide, Colorado Department of Revenue | H.B. 21-1327, Colorado General Assembly

Colorado imposes a flat corporate income tax rate of 4.4% on the Colorado net income of C corporations doing business in the state for income tax years commencing on or after January 1, 2022. This rate is codified in C.R.S. § 39-22-301(1)(d)(I)(K). The tax applies to net income derived from sources within Colorado, which includes income from tangible or intangible property located in the state and income from any activities carried on in Colorado.

The 4.4% rate may be temporarily reduced to 4.25% for certain tax years when excess state revenues trigger TABOR refund requirements under C.R.S. § 39-22-627. For tax year 2024, the rate was temporarily reduced to 4.25%.

Source: Corporate Income Tax Guide, Colorado Department of Revenue | Corporate Income Tax, Colorado General Assembly

A foreign C corporation has substantial nexus with Colorado for corporate income tax purposes if it exceeds any one of the following factor-presence thresholds during the tax year: $50,000 of property (average value of real and tangible personal property owned or rented in Colorado), $50,000 of payroll (compensation paid in Colorado), $500,000 of sales (gross receipts sourced to Colorado), or 25% of its total property, payroll, or sales in Colorado. Corporations organized or commercially domiciled in Colorado automatically have substantial nexus. A corporation is doing business in Colorado when it has substantial nexus and its activities exceed the protections of Public Law 86-272, which protects only solicitation of orders for sales of tangible personal property approved and shipped from outside Colorado.

Source: Corporate Income Tax Guide, Colorado Department of Revenue

Colorado uses a single-factor apportionment formula based on receipts for tax years beginning on or after January 1, 2019. Under C.R.S. § 39-22-303.6(4)(a), a multi-state corporation apportions its business income to Colorado by multiplying that income by a fraction: the numerator is receipts sourced to Colorado, and the denominator is receipts everywhere. Receipts from sales of tangible personal property are sourced to Colorado if the property is delivered or shipped to a purchaser in Colorado. All other receipts are sourced to Colorado if the taxpayer's market for the sale is in Colorado; for services, this means the extent the service is delivered to a Colorado location.

Source: C.R.S. § 39-22-303.6, Colorado Department of Revenue

Colorado C corporation income tax returns (Form DR 0112) are due on the fifteenth day of the fifth month following the close of the taxable year. For calendar-year filers, this means the return is due May 15. This deadline applies to tax years beginning on or after January 1, 2024. An automatic six-month extension to file is available, but at least 90% of the tax liability must be paid by the original due date to avoid penalty. If the due date falls on a weekend or holiday, the deadline is the next business day.

This section has been updated as of June 2024 to reflect the Colorado Department of Revenue's published deadline in its Taxes & Fees Due Date Guide, which states C corporation income tax returns are due the fifteenth day of the fifth month (May 15 for calendar year filers). The prior guide reference to the fourth month (April 15) is superseded by this official guidance.

Source: Colorado Taxes & Fees Due Date Guide, Colorado Department of Revenue Source: DR 0158-C Extension Form, Colorado Department of Revenue

Colorado requires affiliated C corporations that meet common ownership and unitary business tests to file a combined report. Significant changes to the statutory framework take effect for tax years beginning on or after January 1, 2026.

Common ownership requirement Under C.R.S. § 39-22-303(8)(b)(I), all members of an affiliated group of C corporations that are members of a unitary business must file a combined report as a combined group. The common ownership prong requires that at least 50% of the stock of each corporation in the group be owned (directly or indirectly) by a common parent or another includible corporation, with the parent owning more than 50% of at least one includible corporation. This test applies both before and after 2026.

Unitary business test — tax years beginning before January 1, 2026 For tax years beginning before January 1, 2026, Colorado applies a statutory “six-tests-of-unity” standard codified in C.R.S. § 39-22-303(11). An affiliated C corporation is includible in a combined return only if at least three of the following six facts have existed in the current tax year and the two preceding tax years: (1) sales or leases between affiliates; (2) joint advertising; (3) shared officers/directors; (4) joint use of facilities; (5) centralized functions (accounting, legal, HR); and (6) common executive force. This test is unique to Colorado.

Unitary business test — tax years beginning on or after January 1, 2026 (new law) For tax years beginning on or after January 1, 2026, following the enactment of H.B. 24-1134, Colorado REPEALS the “six-tests-of-unity” regime and adopts a unitary business definition modeled on the Multistate Tax Commission (MTC) standard. The new law defines a unitary business as a group with “functional integration, centralized management, and economies of scale,” consistent with leading U.S. Supreme Court and MTC guidance. The prior requirement to satisfy at least three of six facts is ABOLISHED. Now, if corporations are engaged in a unitary business under the new definitional standard, they must be included in the combined report.

Summary of the transition

• For tax years before 2026: require three-of-six unity tests (plus continuity).
• For tax years 2026 and after: follow MTC model “unitary business” definition; no minimum number of factors, and no continuity requirement over prior years.

Apportionment within a combined group (Finnigan rule) For tax years beginning on or after January 1, 2022, combined group apportionment factor numerators include amounts sourced to Colorado from any group member, regardless of nexus in Colorado (the Finnigan rule, C.R.S. § 39-22-303(11)(c)(II)(B)). Intercompany transactions are eliminated from both apportionment numerator and denominator.

Consolidated vs. combined returns Colorado distinguishes between combined reporting (mandatory for unitary groups meeting the above tests) and consolidated reporting (elective under C.R.S. § 39-22-303(12) for IRC § 1504 affiliated groups doing business in Colorado). A taxpayer may file a combined, consolidated, or combined-consolidated return depending on circumstances. Only C corporations doing business in Colorado may be included in a consolidated return.

Effective date and statutory change The replacement of the six-tests-of-unity framework with the MTC model unitary business test is effective for tax years beginning on or after January 1, 2026, as enacted by Colorado H.B. 24-1134 and the corresponding amendments to C.R.S. § 39-22-303. The new statute should be reviewed for detail when preparing returns for 2026 and subsequent years.

Source: C.R.S. § 39-22-303 | Colorado General Assembly, H.B. 24-1134 Bill Text and Summary | Colorado Department of Revenue, Corporate Income Tax Guide

Colorado C corporations calculate their Colorado net income by starting with federal taxable income and then applying Colorado-specific additions and subtractions as mandated by statute. Under C.R.S. § 39-22-304(1)(a), the net income of a C corporation is defined as the corporation's federal taxable income for the taxable year, with statutorily prescribed modifications. Federal taxable income generally appears on line 30 of federal Form 1120 (or line 11 of Form 990-T for unrelated business income).

Modifications: Additions and Subtractions (through tax year 2026)

Colorado conforms to the Internal Revenue Code on a rolling basis; thus, most federal deductions and adjustments flow through to the Colorado return. However, Colorado law requires specific statutory additions and subtractions:

• Required additions per C.R.S. § 39-22-304(2) include: foreign income taxes deducted federally, out-of-state municipal bond interest, the federal NOL deduction (as Colorado computes its own NOL), state income taxes deducted federally, discriminatory club expenses, certain conservation easement credits, and other targeted anti-abuse and COVID-era add-backs. Colorado does NOT have a general related-party interest/intangible expense addback.
• Permitted subtractions per C.R.S. § 39-22-304(3) include: interest from obligations of the U.S., gains from property with higher Colorado basis, pollution control amortization, certain charitable contributions, subtraction for carryforwards of disallowed federal deductions, the Colorado NOL deduction (computed separately), certain dividend income, certain CARES Act adjustments, and the IRC § 78 gross-up. Additionally, a portion of foreign source income is excluded under C.R.S. § 39-22-303(10).

After these modifications, multistate corporations apportion their business income using Colorado’s single-factor receipts method under C.R.S. § 39-22-303.6(4)(a). The apportioned income is then subject to the state tax rate.

Material Change (Effective for tax years beginning January 1, 2027)

House Bill 26‑1222, enacted in 2026, adds new required state-level modifications to federal taxable income for corporations, effective for tax years beginning on or after January 1, 2027:

• Corporations will be required to add back certain federal deductions for business interest (

relating to the limitation of business interest under IRC § 163(j)), specifically the deduction attributable to depreciation, amortization, and depletion that was allowed for federal purposes—but which must now be added back for Colorado purposes (C.R.S. § 39-22-304(2)(r), effective 2027). This aligns with recent federal changes phasing out the addback for these amounts at the federal level beginning 2027.

• The new law also requires a corresponding modification relating to federal bonus depreciation for tangible property under IRC § 168(k), requiring a Colorado-specific adjustment for depreciation in excess of the Colorado-allowed amount (C.R.S. § 39-22-304(2)(s)).

The Department of Revenue and the General Assembly have published legislative summaries and fiscal notes confirming these additions and their 2027 effective date. The changes are intended to decouple Colorado’s calculation of state taxable income from post-2026 federal law for the specified items only; all other modifications remain as under prior statute unless subsequently amended.

Summary:

• For tax years through 2026, modifications are as detailed above;
• For tax years beginning January 1, 2027, and later, corporations must also add back:
• The portion of the business interest deduction attributable to depreciation, amortization, and depletion as required under C.R.S. § 39-22-304(2)(r);
• Any excess federal depreciation deductions under IRC § 168(k) beyond the state-allowed amount under C.R.S. § 39-22-304(2)(s).

Practitioners preparing 2027 Colorado corporate tax filings should review the updated statute and DOR guidance as forms and instructions are issued for the 2027 filing season.

Source: C.R.S. § 39-22-304 (2024 & 2027, as amended by HB26-1222) | C.R.S. § 39-22-303, Colorado General Assembly | C.R.S. § 39-22-303.6, Colorado General Assembly | Corporate Income Tax Guide, Colorado Department of Revenue

Colorado C corporations must remit quarterly estimated income tax payments if the corporation can reasonably expect its net Colorado tax liability to exceed $5,000 for the year. No penalty is due if the corporation's Colorado tax liability for the year is less than $5,000.

Quarterly payment due dates

Estimated tax payments are due in four installments on the 15th day of the 4th, 6th, 9th, and 12th month of the corporation's tax year. For calendar-year C corporations, these dates are April 15, June 15, September 15, and December 15. Fiscal-year filers adjust these dates accordingly based on their tax year. If a due date falls on a Saturday, Sunday, or state holiday, the payment is due on the next business day.

Estimated tax payments must be submitted in the same manner (separate, consolidated, or combined) and using the same account number that the corporation expects to use when filing the Colorado corporation income tax return (Form DR 0112).

Calculation of net Colorado tax liability

For purposes of the estimated tax computation, the Colorado tax liability is defined as the total amount of Colorado tax plus the recapture of prior year credits, minus all income tax credits other than withholding credits and estimated tax credits. This definition is codified in Colorado Department of Revenue regulation 1 CCR 201-2, Rule 39-22-606.

Required annual payment and safe harbor provisions

The required annual amount to be paid is the lesser of:

• 70% of the corporation's net Colorado tax liability for the current tax year, or
• 100% of the corporation's net Colorado tax liability for the preceding tax year (if the corporation filed a Colorado return for the prior year covering a full twelve months).

Each quarterly installment payment is generally 25% of the required annual payment. If three payments are required, each installment must be 33% of the required annual payment. If two payments are required, each installment must be 50% of the required annual payment. If only one payment is required, the payment must be 100% of the required annual payment.

These safe harbor thresholds are established in C.R.S. § 39-22-606(5)(b), which provides that the required annual payment means "the lesser of: Seventy percent of the taxpayer's actual Colorado tax liability shown on the return for the taxable year or, if no return is filed, seventy percent of the tax for such year; or One hundred percent of the taxpayer's actual Colorado tax liability shown on the return of the corporation for the preceding taxable year." The 100% prior-year safe harbor does not apply if the preceding taxable year was not a twelve-month period or if the taxpayer did not file a Colorado return for that year.

Large corporation exception

Corporations defined under IRC § 6655 as "large corporations" can base their first quarter estimated tax payment on 25% of the previous year's tax liability. However, future payments (second, third, and fourth quarters) must be based on the actual tax liability for the current tax year, and any underpayment occurring in the first quarter as a result of using the prior-year estimate must be repaid with the second quarterly payment. C.R.S. § 39-22-606(5)(c)(I) provides that "the first required installment … for any taxable year may be based on twenty-five percent of the taxpayer's actual Colorado tax liability shown on the return of the corporation for the preceding year" and that "[a]ny reduction in the first installment … shall be recaptured by increasing the amount of the next required installment."

Annualized income installment method

Corporations that do not receive income evenly during the year may elect to use the annualized income installment method to compute their estimated tax payments if they elected annualized installments or adjusted seasonal installments for payment of their federal income tax. Under this method, the required installment payment on each due date is the Colorado tax liability computed by annualizing the income received during the months of the tax year ending on the last day of the month before the due date for the installment payment, minus the total of any earlier installment payments made for the tax year.

If tax is computed by apportioning income, apportionment factors must be computed for each quarter in order to use the annualized income installment method. Use of estimated or prior-year apportionment factors is not accepted. A schedule and explanation of the allocation methodology must be made available to the Colorado Department of Revenue upon request when using the annualized method. These requirements are set forth in 1 CCR 201-2, Rule 39-22-606.

Underpayment penalty

The estimated tax penalty for C corporations is assessed if the required estimated tax payments are not paid in a timely manner. The penalty is calculated as the appropriate Colorado income tax interest rate multiplied by the underpayment for each quarter multiplied by the underpayment period. No penalty is due if the Colorado tax liability is less than $5,000. If a short taxable year is involved, the income must be placed on an annual basis, in which case the $5,000 requirement for filing estimated tax payments applies in the same manner as for a full-year taxpayer. C.R.S. § 39-22-606(3)(a) provides that "in the case of any underpayment of estimated tax by a corporation, there shall be added to the tax … for the taxable year an amount determined by applying the rate of interest established under section 39-21-110.5 to the amount of the underpayment for the period of the underpayment."

Payment crediting

Payments are credited against the earliest quarterly installment due for the tax year, regardless of when the payment is received.

Source: C.R.S. § 39-22-606, Colorado General Assembly | 1 CCR 201-2, Rule 39-22-606, Colorado Secretary of State | Business Income Tax Estimated Payments, Colorado Department of Revenue | DR 0112EP Corporate Estimated Income Tax Payment Form, Colorado Department of Revenue

Colorado generally exempts insurance companies from corporate income tax if they are subject to the state's insurance premium tax. However, "disqualified insurance companies" are an exception to this rule: they are excluded from the premium tax exemption and therefore remain subject to Colorado corporate income tax.

Definition of disqualified insurance company

A "disqualified insurance company" is a company licensed as a captive insurance company under Colorado law or the laws of another jurisdiction with gross receipts for the taxable year that consist of fifty percent or less of premiums from arrangements that constitute insurance for federal income tax purposes. This definition is codified at C.R.S. § 10-1-102(6.5).

The defining characteristic is the premium composition test: if 50% or less of the company's gross receipts come from arrangements that qualify as insurance for federal income tax purposes, the company is disqualified. This test targets captive insurance arrangements that may not constitute true insurance under federal tax law—often those involving related-party transactions or arrangements that fail to meet federal insurance standards under the Internal Revenue Code, lack sufficient risk distribution or risk shifting, or otherwise do not meet federal insurance requirements.

Exclusion from premium tax and resulting income tax obligation

Disqualified insurance companies are expressly excluded from the insurance premium tax regime. C.R.S. § 10-3-209(1)(a) and § 10-6-128(1) (for captive insurers) both state that all insurance companies or captive insurance companies doing business in Colorado, "except a disqualified insurance company," shall pay the premium tax to the Division of Insurance.

Because disqualified insurance companies are excluded from the premium tax, they do not qualify for the general exemption from corporate income tax afforded to insurers paying the premium tax. Consequently, a disqualified insurance company that is organized as a C corporation and meets the nexus and doing-business tests is subject to Colorado corporate income tax under the standard rules applicable to all C corporations doing business in the state.

Effective date and purpose

The disqualified insurance company carve-out was enacted by H.B. 21-1311, effective June 23, 2021. The Colorado General Assembly's summary of the bill explains that sections 10 through 13 of the act "address the avoidance of income tax by certain captive insurance companies." The legislative intent was to close a perceived tax avoidance opportunity whereby captive insurance companies—particularly those with premium arrangements that do not constitute insurance for federal tax purposes—could avoid both premium tax (by not having sufficient qualifying premiums) and corporate income tax (by claiming insurer status).

Interaction with combined reporting

A disqualified insurance company that is subject to Colorado corporate income tax and is part of an affiliated group meeting the common ownership and unitary business tests under C.R.S. § 39-22-303 must be included in the combined group's combined return under the rules set forth in that statute. The company's income, apportionment factors, and intercompany eliminations are treated the same as any other C corporation member of the combined group. The insurance-specific premium tax treatment does not affect combined reporting obligations once the company is classified as subject to corporate income tax.

Source: C.R.S. § 10-1-102, Colorado General Assembly | C.R.S. § 10-3-209, Colorado General Assembly | H.B. 21-1311, Colorado General Assembly

Colorado C corporations must make specific additions to federal taxable income when computing their Colorado net income. The list of statutory addbacks has changed significantly for tax years beginning on or after January 1, 2027. This update summarizes required addbacks through 2026 and highlights the new and expanded additions for 2027 and later.

Additions required for all years (through 2026)

• State income taxes (excluding Colorado severance tax): under C.R.S. § 39-22-304(2)(d), add back state income taxes deducted on the federal return.
• Foreign income, war profits, or excess profits taxes: C.R.S. § 39-22-304(2)(a).
• Out-of-state municipal bond interest: C.R.S. § 39-22-304(2)(b), applies to obligations other than those from Colorado issuers.
• Federal net operating loss deduction: C.R.S. § 39-22-304(2)(c).
• Prohibited labor services expenses, discriminatory club expenses, conservation easement credits, certain COVID-related or CARES Act deductions: see various subsections of C.R.S. § 39-22-304(2).
• Qualified business income deduction under IRC § 199A (QBI deduction): must be added back for tax years commencing before, on, and after Jan. 1, 2026 (made permanent by HB25B-1001, repealing the sunset).
• Business meals deduction (IRC § 274(k)): for 2024 through 2030, Colorado requires addback of the federal meals deduction.
• No Colorado addback for related-party intangible or interest expenses.

Material changes for tax years beginning on or after January 1, 2027

Recent 2026 legislation (HB26-1222 and HB26-1289) introduced multiple new additions, effective for C corporations for 2027 returns and going forward. Practitioners must review these changes for 2027 compliance.

• IRC § 1400Z-2 Opportunity Zone gain addback — Corporations must add back any capital gains excluded federally under IRC § 1400Z-2 (Qualified Opportunity Fund/Zone provision).
• Repeal of IRC § 280C disallowed wage deduction addback — The statute eliminates the addback for certain wage deductions previously limited under IRC § 280C.
• CFC inclusions (IRC §§ 951 & 951A) — Colorado requires the addback of amounts deducted federally for Controlled Foreign Corporation income inclusions (Subpart F and GILTI) to prevent double benefit.
• Bonus depreciation and depreciation limitation (IRC § 168(k)) — Corporations must add back excess federal depreciation above the state-allowed amount.
• Business interest limitation (IRC § 163(j)) — Colorado requires recovery (addback) of certain business interest deductions disallowed federally but permitted under pre-2022 federal law.
• Research and experimental expenditures (IRC § 174) — Any deduction for research and experimentation expenses required to be capitalized federally but deducted for state purposes must be added back to income, aligning with federal reversal of expensing.

Practitioners should note the effective date (tax years beginning on or after Jan. 1, 2027) and refer to the official legislative text for precise mechanical rules, definitions, and transitional details. Department of Revenue guidance is expected to be updated before the 2027 filing season, but the statutes control.

Summary of statutory evolution

• Through 2026: Addbacks include state taxes, foreign income taxes, municipal bond interest, NOLs, QBI deduction, certain expenses/credits, and meals deduction (2024–2030).
• 2027 and after: Above items plus new addbacks for opportunity zone gain, bonus depreciation, expanded interest limitation, certain CFC inclusions, R&D expenditures as detailed in HB26-1222 and HB26-1289.

Source: C.R.S. § 39-22-304 Source: HB25B-1001 (2025 Ex. Sess.) Source: HB26-1222 (2026) Source: HB26-1289 (2026)

Colorado allows C corporations to deduct net operating losses (NOLs) from Colorado taxable income under a separate state regime that differs from the federal NOL rules. Because Colorado requires taxpayers to add back the federal NOL deduction when computing Colorado net income, corporations must calculate and claim a Colorado-specific NOL deduction.

Computation of Colorado net operating loss

Under C.R.S. § 39-22-504(1)(a), a net operating loss deduction is allowed "in the same manner that it is allowed under the internal revenue code except as otherwise provided in this section." The Colorado NOL is computed using the same federal rules for determining what constitutes a net operating loss, but the amount is based on the portion of the federal NOL allocated to Colorado under the state's apportionment and allocation rules for the year the loss was sustained.

For multi-state corporations, the Colorado NOL equals the federal NOL multiplied by the Colorado apportionment percentage for the loss year. The Colorado NOL is further modified by Colorado-specific additions and subtractions required under C.R.S. § 39-22-304(2) and (3), such as the addback of state income taxes and the subtraction of U.S. government bond interest.

Carryforward periods — no carryback allowed

Colorado C corporations may not carry back NOLs to prior tax years, regardless of whether federal law allows carrybacks. C.R.S. § 39-22-504(3)(a) and (3)(b) expressly prohibit carrybacks for all corporate NOLs.

For NOLs generated in income tax years commencing before January 1, 2021, Colorado allows carryforward for the same number of years as allowed for a federal NOL. Because federal law enacted in 2017 (the Tax Cuts and Jobs Act) permits indefinite carryforward for federal NOLs arising in tax years beginning after December 31, 2017, Colorado NOLs arising in such years also carry forward indefinitely under the conformity rule in C.R.S. § 39-22-504(3)(a).

For NOLs of corporations generated in income tax years commencing on or after January 1, 2021, Colorado decoupled from the federal indefinite carryforward rule and instead allows a twenty-year carryforward period under C.R.S. § 39-22-504(3)(b), enacted by H.B. 20-1024 in June 2020.

Eighty percent limitation for post-2017 losses

For losses incurred after December 31, 2017, the eighty percent limitation set forth in IRC § 172(a)(2) applies to Colorado NOL deductions. Under C.R.S. § 39-22-504(1)(b), this 80% limitation applies "without regard to the amendments made in section 2303 of the March 2020 'Coronavirus Aid, Relief, and Economic Security Act.'" This means that even though the federal CARES Act temporarily suspended the 80% cap for certain federal tax years, Colorado did not adopt that suspension.

The 80% limitation restricts the annual Colorado NOL deduction to the lesser of (1) the available Colorado NOL carryforward, or (2) 80 percent of Colorado taxable income before the NOL deduction (for losses arising in tax years beginning after December 31, 2017). The limitation applies after deducting any Colorado NOL arising in a tax year beginning prior to January 1, 2018, which is not subject to the 80% cap.

Temporary $250,000 annual limitation (tax years 2011–2013)

For tax years commencing on or after January 1, 2011, but prior to January 1, 2014, Colorado imposed a temporary cap on the annual Colorado NOL deduction. Under C.R.S. § 39-22-504(6)(a), the maximum NOL deduction for those years was $250,000. Corporations affected by this limitation were allowed to carry forward the disallowed portion of the NOL for one additional year beyond the standard carryforward period, and the unused portion was increased by 3.25% annually under C.R.S. § 39-22-504(6)(b) and the corresponding Department of Revenue regulation. This limitation is no longer in effect for tax years beginning on or after January 1, 2014.

Ordering and allocation rules

Colorado NOLs must be carried forward to the tax year immediately following the year the loss was sustained, and losses must be applied in chronological order (oldest loss first). If a C corporation has available NOL carryforwards originating in multiple tax years, the corporation must first deduct the loss arising from the earliest tax year.

For combined or consolidated groups, the Colorado NOL is calculated with respect to only the C corporations included in the combined or consolidated return and is based on the federal NOL determined for that group. Intercompany eliminations and apportionment rules apply at the group level.

Interaction with federal NOL addback and subtraction

As noted in C.R.S. § 39-22-304(2)(c), C corporations must add back to federal taxable income the full amount of the federal NOL deduction claimed on the federal return. After making this addback and computing Colorado net income (including Colorado-specific modifications and apportionment), the taxpayer may then subtract the Colorado NOL deduction as a modification under C.R.S. § 39-22-304(3)(g). This ensures that Colorado NOLs are calculated and applied independently of federal NOLs.

Section 382 and other federal limitations

Federal limitations on NOL usage, including the IRC § 382 limitation on NOLs following an ownership change, apply for Colorado purposes. For purposes of applying the IRC § 382 limitation to Colorado NOLs, the limitation amount is apportioned to Colorado using the Colorado apportionment fraction of the loss corporation for the last full tax year prior to the ownership change. Similarly, other federal NOL limitation rules (such as the separate return limitation year rules for consolidated groups) generally apply to Colorado NOLs.

Source: C.R.S. § 39-22-504, Colorado General Assembly | H.B. 20-1024, Colorado General Assembly | H.B. 20-1420, Colorado General Assembly

C corporations subject to Colorado corporate income tax may claim a variety of credits as detailed in Title 39, Article 22 of the Colorado Revised Statutes. Each credit has distinct eligibility, calculation, and carryforward rules; statutory language should be reviewed carefully for each.

Statutory framework and notable credits Colorado’s primary statutory corporate credits include:

• Investment Tax Credit (for qualified tangible property used in Colorado): Generally available for property placed in service prior to January 1, 2023, with carryforward of unused amounts for up to 12 years. See C.R.S. § 39-22-507.6(2), (4), (6).
• Gross Conservation Easement Credit: Available for donation of a perpetual conservation easement, with credit amounts and 20-year carryforward as described in C.R.S. § 39-22-522(5). Detailed filing and transfer rules apply.
• Enterprise Zone Investment Credit (C.R.S. § 39-30-104): 3% of qualified investment in eligible enterprise zones; most unused credits may be carried forward for 12 years.
• Historic Property Preservation Credit: See C.R.S. § 39-22-514(6). Unused credit may be carried forward for 10 years.
• Colorado Coal Credit: C.R.S. § 39-22-308.
• Child Care Contribution Credit: C.R.S. § 39-22-121.

Each credit’s section in the statutes governs its requirements, amount, and limitation period. A summary page with links to current forms and statutes is maintained by the Department of Revenue, but eligibility and calculation are determined solely by statute/regulation.

Claiming credits Credits are generally claimed on the Colorado C corporation income tax return (Form DR 0112), with supporting forms as required (e.g., DR 1366 for the Schedule of Credits; DR 0074 for Conservation Easements; DR 0078 for Enterprise Zone credits). Most credits are nonrefundable—they may reduce tax liability to zero, but cannot generate a refund.

Carryforward and use limitations Statutory carryover rules differ by credit:

• Investment Tax Credit (pre-2023 property): up to 12 years (C.R.S. § 39-22-507.6(4)).
• Gross Conservation Easement: 20 years (C.R.S. § 39-22-522(5)).
• Enterprise Zone Investment: 12 years (C.R.S. § 39-30-104(2)(a)(III)).
• Historic Preservation: 10 years (C.R.S. § 39-22-514(6)).

Generally, credits must be used in the earliest possible year, with amounts carried forward not allowed past the statutory limit.

Official resources

• For current forms, supplemental schedules, and a navigational list of all credits (with statute links), see the Colorado DOR’s Income Tax Credits page (note this is a secondary aggregator, not primary statutory authority): https://tax.colorado.gov/income-tax-credits
• Instructions for return preparation: Form DR 0112 Instructions

Source: C.R.S. § 39-22-507.6 | C.R.S. § 39-22-522 | C.R.S. § 39-30-104 | C.R.S. § 39-22-514 | C.R.S. § 39-22-308 | C.R.S. § 39-22-121 | Income Tax Credits, Colorado Department of Revenue | Form DR 0112, Colorado Department of Revenue

Colorado C corporations are subject to statutory penalties and interest for noncompliance with income tax filing and payment obligations. This section summarizes the key provisions for late filing, late payment, underpayment of estimated taxes, and penalty abatement, with direct citations to the relevant statutes, regulations, and published guidance.

Late filing and late payment penalties Under C.R.S. § 39-22-621(1), the penalty for failure to file a return or pay tax by the due date is the greater of $5 or 5% of the unpaid tax, plus an additional 0.5% for each full month or fraction thereof during which the failure continues, not to exceed a total penalty of 12% of the unpaid tax. The penalty may be waived if (a) at least 90% of the total tax shown is paid on or before the original due date, (b) the return is filed by the extended due date, and (c) any remaining balance is paid with the return. This framework applies to both filing and payment, as confirmed in regulation.

Underpayment of estimated tax penalty C corporations with expected net Colorado tax liability above $5,000 must make quarterly estimated payments. Under C.R.S. § 39-22-606(3)(a), if the required estimated payments are not made, there is a penalty in the form of interest imposed on the underpaid amount for the period of underpayment, computed at the statutory interest rate (see below). The penalty does not apply if the net Colorado tax liability for the year is below $5,000. Regulation 1 CCR 201-2, Rule 39-22-606 details the calculation and credits for late or partial payments.

Interest on late payment and deficiencies Interest accrues on unpaid tax from the original due date (regardless of extension) until the tax is paid in full. Per C.R.S. § 39-21-110.5, Colorado prescribes two annual rates: a discounted rate (applicable if payment is made before or within 30 days of a notice of deficiency, or timely under an approved installment agreement), and a regular rate otherwise. For 2026, the interest rates are 8% (discounted) and 11% (regular), as published annually by the DOR.

Accuracy and fraud penalties C.R.S. § 39-22-621(2) imposes an additional penalty of up to 20% of the underpayment attributable to negligence or disregard of rules/regulations. In cases of fraud with intent to evade tax, a 50% penalty applies.

Penalty abatement and reasonable cause relief Under C.R.S. § 39-22-659, the Department of Revenue may waive, reduce, or compromise penalties (but not interest except as specifically authorized) for reasonable cause. 1 CCR 201-2, Rule 39-22-621(3) requires taxpayers to provide an affirmative showing of all facts alleged as a basis for relief; the department will consider the totality of circumstances, but the regulation does not list exhaustive examples.

Sources:

• Source: C.R.S. § 39-22-621
• Source: C.R.S. § 39-22-606
• Source: C.R.S. § 39-21-110.5
• Source: C.R.S. § 39-22-659
• Source: 1 CCR 201-2, Rule 39-22-621, Colorado Secretary of State
• Source: Colorado DOR: Tax Topics—Penalties and Interest

A Colorado C corporation disputing a proposed corporate income tax assessment or denial of a refund must file a written protest with the Executive Director of the Colorado Department of Revenue within 30 days of the mailing date of the Notice of Deficiency or refund denial. This requirement is set by C.R.S. § 39-21-103. The protest must identify the taxpayer and contact information, specify the tax periods and amounts in dispute, and provide an itemized schedule and summary of the grounds for protest; it must be signed by an officer or authorized representative. Accepted submission methods are outlined in the CDOR's instructions and include Revenue Online and mail.

After the protest is received, an initial informal review is typically conducted by the Tax Conferee Section, which may include conferences focused on resolving factual questions. If unresolved, the taxpayer may request (or will be scheduled for) a formal administrative hearing before the Executive Director or a designated hearing officer (C.R.S. § 39-21-103(3)-(7)). Hearings are generally held in Denver unless otherwise arranged as permitted by agency policy or the hearing officer. Taxpayers may appear on their own behalf or be represented by an authorized individual; attorney representation is not categorically required. Both parties may present testimony and evidence, submit arguments, and may be represented by counsel if they wish. Hearings are not open to the public by statute, but agency practice is to keep them closed.

The Executive Director must issue a written final determination within 60 days of the hearing; this deadline may be extended in 60-day increments for good cause with notice to the parties (C.R.S. § 39-21-103(8)). After the final determination is mailed, the taxpayer has 30 days to file an appeal in Colorado district court (C.R.S. § 39-21-105). District court review is de novo, meaning the court decides the case anew rather than reviewing the Department’s findings. Venue generally depends on the taxpayer’s principal business location in Colorado, or Denver District Court if not located in Colorado. Standard Colorado Rules of Civil Procedure apply. The procedural framework described herein is current as of 2026 under C.R.S. Title 39, Article 21 and CDOR guidance.

Forms and instructions for submitting a protest, including required information and available submission methods, are provided on the official CDOR "File a Protest" and "Administrative Hearings" webpages.

Source: C.R.S. § 39-21-103 | C.R.S. § 39-21-105 | CDOR – Administrative Hearings | CDOR – File a Protest

Direct answer: Before tax years beginning on January 1, 2027, Colorado mandates worldwide combined reporting for unitary groups, generally including both domestic and foreign affiliates, unless a foreign corporation has at least 80% of its property and payroll outside the United States or its possessions. For tax years beginning on or after January 1, 2027, Colorado permits an elective water’s-edge combined reporting method, under which only certain affiliates—domestic, defined foreign, U.S.-connected, and certain tax haven entities—are included in the combined group.

Why:

• Pre-2027 mandatory worldwide reporting with an 80% exclusion:

Under C.R.S. § 39-22-303(8), all domestic corporations and commonly owned unitary affiliates (including foreign corporations) are included in a Colorado combined return. However, “a corporation incorporated in a foreign jurisdiction is not included in the combined group if eighty percent or more of its property and payroll is assigned outside the United States and its possessions” (C.R.S. § 39-22-303(8)(a)). Sales are not considered for this exclusion; only property and payroll.

• Water’s-edge election effective for 2027 and after:

H.B. 1289 (2026) allows, for tax years beginning on or after January 1, 2027, a water’s-edge election (to be codified at C.R.S. § 39-22-303(8)(e)). With a valid election, the combined group includes:

• Domestic corporations;
• Foreign corporations with at least 20% of their property, payroll, or sales assigned within the U.S.;
• Domestic International Sales Corporations (DISCs) and foreign sales corporations, to the extent of U.S.-connected income;
• Certain tax haven corporations—specifically, foreign affiliates incorporated in a country designated by the Department of Revenue as a “tax haven” and that earn more than 20% of their gross income from intangible property or related-party services directly or indirectly for U.S. persons.

The election is binding for ten years unless revoked or invalidated by statute/regulation. If the taxpayer makes no election, the default remains worldwide combined reporting, subject to the 80% exclusion above.

Anti-abuse provisions in the statute require inclusion of U.S.-source income, and the definition of “tax haven” and criteria for related-party service or intangible income are spelled out in the bill’s statutory text.

As of June 16, 2026, the Colorado DOR Corporate Income Tax Guide does not include specific procedures or forms for the 2027 water’s-edge election—practitioners should monitor for regulatory updates and implementation guidance.

Source support: Source: C.R.S. § 39-22-303(8)(a)-(c) Source: Colorado Department of Revenue, Corporate Income Tax Guide (pre-2027 combined rules) Source: H.B. 1289 (2026), Sec. 4, to be codified at C.R.S. § 39-22-303(8)(e)

Caution / review status: Not yet human confirmed. As of June 16, 2026, no detailed DOR guidance or finalized water’s-edge procedures are published for the 2027 transition. Statutory framework governs; practitioners should re-verify with department-issued regulations as the effective date approaches.

Direct answer For tax years commencing on or after January 1, 2027, Colorado’s water’s-edge election must be made on a “timely filed, original” corporate income tax return; it is binding for the election year plus the next nine years, automatically renews unless withdrawn, and may only be withdrawn or reinstated with the approval of the Executive Director under conditions of reasonable cause; however, Colorado has not yet published administrative forms, required statement content, cure procedures, or anti-abuse or transition rules as of July 8, 2026.

Why House Bill 26-1289 (enacted June 3, 2026; § 39-22-303(8.5)(c)) establishes:

• Election mechanics: must be made on a “timely filed, original return.”
• Binding term: covers the election year and nine subsequent years (total 10 years).
• Renewal: if not withdrawn, the election is deemed renewed for an additional ten-year period under the same terms.
• Withdrawal or reinstatement: permitted only by timely filed original return or written request under rules, upon showing of reasonable cause (such as extraordinary hardship), subject to conditions to prevent tax evasion or ensure clear reflection of net income.

The bill, however, does not specify:

• Which Colorado form or paper/e-file format is required for the election or withdrawal—e.g., whether taxpayers should attach a statement to DR 0112.
• The precise content of such a statement or how DOR staff will process or cure a filing if it's late, incomplete, or defective.
• Transition-period guidelines for taxpayers bridging 2026 to 2027, or anti-abuse rules beyond withdrawal-for-cause language.

No Colorado DOR regulation, guidance, bulletin, or taxability matrix has been published addressing any of these procedural aspects as of the current date.

Source support

• HB 26-1289 § 39-22-303(8.5)(c), authorizing election mechanics, binding term, renewal logic, withdrawal and reinstatement conditions — legislative act (Colorado General Assembly). https://leg.colorado.gov/bills/hb26-1289

Caution / review status Not yet human confirmed. Procedural mechanics (form, statement content, cure procedures, transition guidance) remain unspecified and unsupported by DOR authority as of July 8, 2026. Practitioners must monitor Colorado DOR publications for forthcoming administrative guidance.

Colorado's combined and consolidated corporate income tax reporting requirements apply primarily to C corporations, but a major statutory amendment effective for tax years beginning on or after January 1, 2026, changes both the test for unity and which entities are to be included.

Statutory framework (through 2025): Under C.R.S. § 39-22-303 (combined returns) and § 39-22-305 (consolidated returns), only entities classified as C corporations are required (or allowed) to be included in a Colorado combined or consolidated return. The statutes and Department of Revenue guidance state: "Only C corporations may be included in combined returns. S corporations, partnerships, non-corporate LLCs, and disregarded entities are not included in the combined group." The inclusion of an LLC is limited to those that have made a federal election to be taxed as a C corporation (IRS Form 8832). Otherwise, default federal classification controls. There is no provision, for tax years through 2025, that requires or permits inclusion of partnerships or non-corporate LLCs (including disregarded entities) unless they are federally classified as C corporations.

Material Change (effective for tax years beginning on and after Jan. 1, 2026): House Bill 24-1134 (signed May 14, 2024) makes substantial amendments to C.R.S. § 39-22-303, moving from Colorado’s “six-facts” unity test to a Multistate Tax Commission (MTC) model rule standard and updating group inclusion. It provides that “all of the members of an affiliated group of C corporations, wherever incorporated or domiciled, that are members of a unitary business shall file a combined report as a combined group.” (Amended § 39-22-303(8)(b), effective 2026.)

Crucially, the amended statute makes clear that for determining the existence of a unitary business, “business conducted by or through a partnership, an S corporation, or any other entity that is not a C corporation is treated as conducted by the owners proportionally to their ownership interest” (§ 39-22-303(11)(c), as amended). Thus, partnership or disregarded entity activities are attributed up to their C corporation owners when testing for unity and determining group composition. However, actual inclusion in the return remains limited to C corporations themselves; non-corporate entities are not separately included but may affect the unity analysis and the business income/apportionment factors of group C corporation members.

Summary of rules:

• Through 2025: Only C corporations (including LLCs federally electing C classification) may be included; all others categorically excluded.
• For 2026 and after: Only C corporations are still included, but unity is determined looking through partnerships, S corps, and disregarded/non-c entities owned, so their activities may cause more C corporations to be combined. Non-corporate entities are not themselves direct filers but are relevant to the combined group boundary.
• Practitioners should review the updated statute and Department guidance for transition years and further implementation detail as new regulations are promulgated for 2026 and later.

Source: C.R.S. § 39-22-303 (2024 & 2026 amended); Corporate Income Tax Guide – Part 2 (Combined & Consolidated Returns), Colorado Department of Revenue; H.B. 24-1134, Colorado General Assembly

Not yet human confirmed as of 2026-06-22. This update reflects material statutory change for tax years beginning January 1, 2026.

When the IRS makes a federal adjustment affecting a combined group’s Colorado return—such as issuing a Revenue Agent’s Report (RAR), making a § 482 adjustment, or otherwise changing federal taxable income—Colorado law affirmatively requires the taxpayer to file an amended Colorado return reflecting the federal change. This duty to notify and amend applies to both increases and decreases in federal taxable income and applies to combined group returns as well as separate filers.

Notice and amendment duty: Under C.R.S. § 39-22-601.5(2)(a), if the taxpayer's federal taxable income, federal tax liability, or federal credits are finally changed by the IRS (including through audit, negotiated settlement, or judicial decision), the taxpayer "shall file an amended Colorado return" to fully report the changes, adjustments, or corrections. This amended return must be filed with the Colorado Department of Revenue within 30 days after the final federal determination is issued. This requirement is not limited to separate filers; it applies to any return impacted by the federal action, including combined group returns. The return must include a copy of the final federal RAR, closing agreement, or other documentation underpinning the change.

Statute of limitations following federal adjustments: For Colorado assessments resulting from federal changes, C.R.S. § 39-21-107(2) provides that the Department may assess additional tax at any time within one year after the taxpayer notifies the Department in writing of the final federal determination. If the taxpayer fails to file the required amended Colorado return, the assessment period is extended until one year after the Department learns of the final federal change. For refunds, C.R.S. § 39-21-108(1)(a)(I)(B) allows the taxpayer to claim a refund within one year of the final federal determination if the refund claim is based on the same federal change (even if the standard four-year period has expired).

Special application to combined returns: The statute does not provide a different notification or limitations period for combined groups; the 30-day filing duty applies to the group as a whole. If the federal adjustment addresses issues that flow through the federal consolidated or combined return (such as an IRC § 482 allocation or an RAR affecting multiple group members), the amendment and notification process must address all entities/amounts impacted on the Colorado combined return. If the Department makes a deficiency determination before the federal change, its jurisdiction in the post-federal-change period is limited to items affected by the federal determination (C.R.S. § 39-22-601.5(4)).

Failure to amend or notify: If a taxpayer does not file the required amended return to report the federal adjustment, the statute of limitations for Colorado assessment does not begin to run—in effect, the Department may make an assessment at any time until one year after notification, regardless of how many years have elapsed since the original Colorado filing. This is an important compliance risk for combined groups with IRS audit adjustments.

Summary timeline:

• File amended Colorado return within 30 days of final federal determination.
• Department may assess tax within one year of notification, or indefinitely if no notification is made.
• Refund claims based on federal changes: one year from federal determination.

Source: C.R.S. § 39-22-601.5 Source: C.R.S. § 39-21-107 Source: C.R.S. § 39-21-108 Source: Colorado Corporate Income Tax Guide, RAR/federal change procedures

Not yet human confirmed as of 2026-06-30.

Direct answer Under Colorado’s corporate income tax regime, for both the current worldwide combined reporting system and the new water’s-edge election (effective for tax years beginning January 1, 2027), foreign-source income—including (1) actual dividends from foreign affiliates, (2) Subpart F inclusions, (3) GILTI inclusions, and (4) IRC § 78 gross-ups—is generally excluded from the denominator of the Colorado apportionment factor to the extent it qualifies for Colorado’s foreign source income exclusion. These categories are included in the exclusion under the Department of Revenue’s Corporate Income Tax Guide. Amounts subtracted as part of the foreign source income exclusion are also disregarded from the numerator when not Colorado-assigned. Distributions from foreign affiliates that do not elect inclusion are treated as foreign-source income only to the extent that classification is recognized under Colorado’s rules.

Why / legal classification

• The Guide (Part 7: Foreign Source Income Exclusion) defines foreign-source income broadly to comprise “dividends, interest, royalties, Subpart F inclusions, GILTI, and gross-up under IRC § 78.” These are subtracted in two places: from federal taxable income in calculating Colorado net income, and from total receipts in the apportionment factor denominator.
• The guide instructs: “For purposes of the denominator of the Colorado apportionment fraction, receipts subtracted as a result of the foreign source income exclusion are not included.”
• For entities included via section 303(8)(b) (including foreign corporations meeting the criteria for combination or water’s-edge), if the federal taxable income of that entity already excluded the item (e.g., under U.S. rules), the amount is disregarded for the exclusion—i.e., not double-subtracted.
• Subpart F and GILTI: These are “foreign source income” by definition (per both statute and guide) and their receipt is generally not included in the apportionment factor’s denominator. The same applies to IRC § 78 gross-up (the deemed-paid foreign tax credit gross-up, which Colorado separately subtracts in full).
• Actual dividends: If the dividend from a foreign affiliate is recognized federally as foreign-source, it is included in the exclusion and not in the denominator. Dividends that are not foreign-source under Colorado rules (e.g., from a U.S. affiliate) do not get this exclusion.
• Non-electing Foreign Affiliates: Distributions from foreign affiliates that are not included in the combined group may be considered foreign-source income only if they meet federal and Colorado sourcing standards. The guide warns that anti-abuse and factual review may apply.
• Numerator: The guide states excluded foreign-source receipts are also excluded from the numerator “except to the extent assigned to Colorado” (typically not applicable unless specific apportionment override applies).
• Water’s-edge: As of June 22, 2026, the published Department guidance treats these receipts identically under worldwide and water’s-edge regimes, as the core exclusion mechanism is unchanged. If the department publishes new water’s-edge-specific rules for 2027 and after, practitioners should review updates.

Example A Colorado-based C corporation receives a $1M GILTI inclusion and $200K in Subpart F income from a controlled foreign corporation. These amounts are recognized as foreign source income by both federal and Colorado law, subtracted from Colorado net income, and not counted in either the numerator or denominator of the apportionment factor. If the corporation also receives a $100K dividend from a U.S. affiliate (not foreign source), that amount stays in the receipts factor.

Source support Source: Colorado Corporate Income Tax Guide, Part 7, Foreign Source Income Exclusion (with mechanical and example instructions)

Caution / review status: Not yet human confirmed. The current Department guidance (as of June 22, 2026) is silent on any material change to denominator exclusion or tracing under the water’s-edge regime for tax years beginning in 2027. If future regulations depart from the worldwide treatment, further review will be required.