Colorado Moves to Worldwide Combined Reporting and Adds a Ten-Year Water’s-Edge Election

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• The previous unitary test has changed. Beginning in 2026, Colorado replaced its distinctive “3 of 6” test with a broader approach based on traditional unitary business principles, potentially changing which corporations must report together.
• Tax modeling is essential. Excluding foreign affiliates does not necessarily reduce tax liability. Foreign operating losses, apportionment factors, and the repeal of Colorado’s 80/20 rule can materially affect the outcome. Businesses should evaluate both methods before making a long-term election.

What Colorado Changed

Colorado has significantly revised its corporate income tax reporting requirements through legislation enacted in 2026. House Bill 1289, signed on June 3, 2026, establishes worldwide unitary combined reporting as the default method for affiliated corporate groups beginning with tax years starting on or after January 1, 2027.

Under this approach, qualifying domestic and foreign corporations conducting a unitary business generally must combine their income and apportionment factors when determining Colorado corporate income tax liability.

Previously, Colorado generally required separate-company filing unless affiliated corporations satisfied the state’s unitary combination requirements. When combined reporting applied, Colorado’s rules generally operated on a water’s-edge basis.

The new legislation permits qualifying groups to elect water’s-edge treatment, but that election must be made on a timely filed original return. Once elected, it generally remains binding for ten years, including the election year and nine succeeding years.

The legislation also repeals Colorado’s 80/20 company exclusion, potentially bringing additional foreign operations into the reporting calculation.

These changes follow legislation effective January 1, 2026, that revised Colorado’s definition of a unitary business. Together, the changes represent a substantial restructuring of Colorado combined reporting requirements and create important decisions for corporations operating across international borders.

How Colorado Filed Before This Change

Unlike the unitary business standard Colorado adopted for tax years beginning on or after January 1, 2026, the state previously used six specific tests of unity to determine whether affiliated C corporations were required to file a combined return. The six tests examined relationships among affiliated companies involving:

• Intercompany transactions: Whether 50% or more of a corporation’s gross receipts or purchases were from or to affiliated corporations.
• Intercompany services: Whether one affiliated corporation provided 50% or more of five or more enumerated services, including legal services, personnel services, and sales services, among others, without provision for an “arm’s length charge” under federal regulations to another affiliated corporation.
• Long-term debt guarantees: Whether 20% or more of an affiliated corporation’s long-term debt was owed to or guaranteed by another affiliated corporation.
• Substantial use of intellectual property: Whether one affiliated corporation substantially used patents, trademarks, service marks, trade secrets, copyrights, or other proprietary materials owned by another affiliated corporation.
• Shared directors: Whether at least 50% of the members of one corporation’s board of directors also served as directors or corporate officers of another affiliated corporation.
• Shared officers: Whether at least 25% of the 20 highest-ranking officers of one affiliated corporation also served as directors or corporate officers of another affiliated corporation.

Before 2026, an affiliated group generally had to satisfy at least three of the six tests for the current year and the two preceding years to be included in a combined return.

Deciding Between Worldwide and Water’s-Edge

For multinational corporations, the decision between worldwide and water’s-edge reporting requires more than determining how much foreign income can be excluded.

Many businesses initially assume that excluding foreign subsidiaries will produce a lower state tax liability. However, two important considerations can make worldwide reporting more favorable.

1. Foreign affiliates may generate losses.

If foreign subsidiaries incur operating losses, including those entities in a worldwide combined return may reduce the group’s overall taxable income. Electing water’s-edge treatment could exclude those losses, potentially increasing the amount subject to Colorado taxation.

2. Foreign operations may reduce the Colorado apportionment percentage.

Colorado apportions business income to determine the portion taxable by the state. Including substantial foreign operations may increase the group’s overall apportionment denominator, reducing the proportion of income attributed to Colorado.

In some circumstances, this reduction can more than offset the additional foreign income included in the worldwide tax base.

The decision also has long-term implications. A water’s-edge election generally applies for ten years and automatically renews for another ten-year period unless properly withdrawn.

Corporations should therefore model projected income, foreign losses, and apportionment factors under both approaches, considering not just the immediate tax year but the potential impact throughout the election period.

What Taxpayers Should Do Before the Election Is Due

Corporations with multi-state or international operations should begin evaluating the changes before preparing their 2027 returns.

A practical review should address the following:

– Reassess the unitary group. Determine which affiliated corporations qualify under Colorado’s revised unitary definition effective in 2026

– Model both filing methods. Calculate projected income, losses, and Colorado apportionment under worldwide and water’s-edge approaches

– Evaluate foreign subsidiaries. Identify companies previously excluded under the 80/20 rule and determine their treatment under the new requirements

– Review financial reporting implications. Assess potential effects on current and deferred tax calculations, including ASC 740 provisions

– Prepare election documentation. Establish internal deadlines and confirm the requirements for making the election on a timely filed original return

– Consider long-term projections. Evaluate anticipated changes in international operations, profitability, and business structure over the ten-year election period

The election is generally binding for ten years, and early withdrawal is limited to specific circumstances requiring approval from the Colorado Department of Revenue.

Businesses should coordinate with their tax advisors before choosing a reporting method. Modeling both alternatives in advance can help identify the approach that best reflects their financial circumstances and anticipated operations.

FAQ

What is a unitary business group?

A unitary business group consists of affiliated corporations whose activities are sufficiently connected through economic integration, centralized management, or functional relationships to constitute a single business enterprise for state income tax purposes. Under Colorado’s revised rules effective in 2026, determining whether a group is unitary follows traditional constitutional principles rather than the state’s former statutory “3 of 6” test.

Which other states require an affirmative water’s-edge election?

In addition to Colorado, California, Idaho, Montana, New Mexico, and North Dakota are among the states requiring qualifying corporations to affirmatively elect water’s-edge treatment rather than automatically applying that filing method. Election procedures, group inclusion rules, and binding periods vary by state. Multistate corporations should review each jurisdiction’s requirements separately rather than assuming an election in one state applies elsewhere.

What happened to Colorado’s 80/20 company treatment?

House Bill 1289 repeals Colorado’s previous 80/20 company exclusion for tax years beginning on or after January 1, 2027. Previously, corporations with at least 80% of their property and payroll assigned outside the United States were excluded from combined reporting. Under the new water’s-edge rules, foreign-incorporated companies with at least 20% of property and payroll assigned domestically are generally included.

How should the change be reflected in an ASC 740 provision?

Corporations should evaluate the legislation’s effect on current and deferred state income taxes under ASC 740, including changes in reporting groups, apportionment, and applicable tax rates. Because the law was enacted in June 2026, its effects may require recognition in the enactment period. Companies should also assess how anticipated elections affect deferred tax measurements and supporting documentation.

How BT Can Help

For more than four decades, Bennett Thrasher has provided businesses and individuals with strategic business guidance and solutions through professional tax, audit, advisory, and business process outsourcing services. Contact Matthew Laney, Director in Bennett Thrasher’s State and Local Tax (SALT) practice, or call us at 770.396.2200.

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