Colorado Voters Decide on Competing Income Tax Measures

Colorado voters cast ballots on 14 statewide measures during the 2026 midterm election on Tuesday. The proposals spanned a wide range of fiscal, legal, and social issues, including constitutional amendments regarding hunting and fishing rights, the sale of natural gas, and increased penalties for child sex trafficking and fentanyl crimes.

Central to the election were two competing income tax measures. Amendment 87, led by the Protect Colorado’s Future Coalition, proposes replacing the state's flat income tax with a graduated system to lower taxes for most residents while increasing them for high earners. Early results showed the measure passing with 50.75% of the vote, with projections suggesting it would generate over $2 billion for childcare, education, and healthcare. In contrast, Proposition 136, sponsored by the conservative think tank Advance Colorado, sought to cap the income tax at the current flat rate of 4.4%. Early returns indicated this measure was failing with 46.75% support.

Other significant measures included a proposal to allocate TABOR refunds to K-12 education and a request for tax increases to fund the Front Range Passenger Rail District. Social measures sought to establish school sports rules based on biological reproductive systems and prohibit certain sex-altering surgeries for minors. Because Amendment 87 and Proposition 136 are legally contradictory, the official ballot information booklet noted that if both were to pass, the resulting conflict would require resolution in court.