Colorado voters will decide two income-tax measures that point in opposite directions: Amendment 87 would create graduated rates and raise taxes on higher incomes, while Proposition 136 would cap the state income-tax rate at 4.4%.

The interaction is not theoretical. The legislature’s official 2026 State Ballot Information Booklet says that if both measures pass, they conflict and “the outcome is unclear.” The General Assembly or a court may have to resolve the question, and the booklet notes that when approved measures conflict, the one receiving more votes generally governs.

Amendment 87 would replace Colorado’s flat individual income-tax structure with six brackets beginning in tax year 2027. The official fiscal impact statement lists rates ranging from 3.7% for taxable income up to $25,000 to 8.4% above $1 million. Rates would be 4.2% from $25,000 to $100,000, 4.4% from $100,000 to $500,000, 7.4% from $500,000 to $750,000 and 7.9% from $750,000 to $1 million.

Legislative analysts estimate the change would raise state revenue by $958.4 million in the partial 2026-27 fiscal year and $1.972 billion in 2027-28, the first full fiscal year. The measure directs the money to public schools, health care and early childhood education and care. Analysts estimate about 3.4 million taxpayers would receive an average $176 annual tax reduction, while roughly 64,000 would pay an average of $39,171 more. The crossover point is estimated at $510,834 in taxable income.

The legislature’s official Amendment 87 analysis presents supporters’ argument that the plan would lower taxes for most filers and provide dedicated funding for public services. Opponents argue that higher top rates could discourage investment, make revenue more volatile and allow spending to expand without sufficient scrutiny.

Proposition 136 takes the narrower approach. Its official ballot analysis says it would set a 4.4% ceiling for state individual and corporate income-tax rates starting Jan. 1, 2027. Because Colorado’s current rate is already below that limit, legislative analysts project no immediate fiscal effect if Proposition 136 passes by itself.

That zero-dollar estimate does not mean the proposition would be inconsequential. A binding cap would limit a future legislature’s ability to raise income-tax rates without another statewide vote. Amendment 87, by contrast, would immediately place several brackets above the proposed cap. The two measures therefore ask not only what tax rates should be, but who should have authority to change them later.

The cap would matter if lawmakers or voters later sought a higher rate — and it directly collides with Amendment 87’s upper brackets. A review by Axios Denver similarly identified the two proposals as competing tax visions on the same ballot.

For voters, the choices are separate: each measure receives its own yes-or-no vote. The official analyses do not promise that approving both would produce a blended system. Instead, they explicitly leave the conflict for a later legal or legislative determination, making the relative vote totals potentially consequential.