Supporters of Colorado's Amendment 87 declared victory Thursday, Nov. 5, saying a graduated income tax will replace the state's flat rate and generate billions for schools and health care.

The Associated Press had not called the race as of 3:15 p.m. Thursday, Denver7 reported. Results at that point showed the measure ahead 50.8% to 49.2%. Colorado Newsline reported that with more than 2.4 million ballots counted, the lead stood at 1.5 percentage points. Many remaining ballots were in populous Front Range counties where the measure was running ahead.

The measure needs only a simple majority to pass because it removes language from the state constitution rather than adding to it, according to Colorado Newsline.

What changes for taxpayers

Amendment 87 would dissolve Colorado's flat 4.4% income tax and replace it with a tiered system. According to 9News, the new brackets would be:

  • First $25,000 of income: 3.7% (down from 4.4%)
  • $25,001 to $100,000: 4.2% (down from 4.4%)
  • $100,001 to $500,000: 4.4% (no change)
  • $500,001 to $750,000: 7.4%
  • $750,001 to $1 million: 7.9%
  • Above $1 million: 8.4%

The state's nonpartisan legislative council staff estimates 3.4 million Coloradans would pay less in income tax, while about 64,000 would pay more, according to 9News. A nonpartisan fiscal analysis estimated the measure would raise $2 billion in additional revenue by the 2027-28 fiscal year, Colorado Newsline reported. The new brackets would apply to both individuals and businesses.

The brackets would apply starting in tax year 2027, meaning the changes would show up on taxes due in 2028, according to 9News. The brackets are the same for single and joint filers and are not indexed for inflation, the Colorado Sun reported.

Revenue earmarked for schools, health care

Chris deGruy Kennedy, president of the Bell Policy Center and a leader of the campaign supporting the measure, said the additional revenue would go toward education, health care and child care, Fox 31 reported. He said lawmakers will have to determine how to prioritize that funding and that spending would be subject to an annual audit.

Colorado Newsline reported that Amendment 87, combined with Proposition NN, which voters also approved, marks the most sweeping set of changes to Colorado tax policy since voters passed the Taxpayer's Bill of Rights (TABOR) in 1992. As we reported Nov. 5, Proposition NN raises the annual revenue growth cap established by TABOR.

Opposition from business groups, governor

The measure faced opposition from Advance Colorado, a conservative political group, and Gov. Jared Polis. Governor-elect Phil Weiser also opposed it, though he said if it passed he would implement it effectively, the Colorado Sun reported.

Michael Fields, president of Advance Colorado, told Fox 31 the potential impact on businesses could be significant. He argued voters may have focused on individual tax changes without fully considering what the measure could mean for businesses.

At the Denver Metro Chamber of Commerce's 2026 Annual Meeting in September, chamber CEO J.J. Ament warned against the measure. "You cannot make Colorado more affordable by making everything more expensive," Ament said, according to a chamber news release.

A rival measure, Proposition 136, which aimed to cap income tax rates at the current 4.4%, was on track Thursday to lose by a 5-point margin, Colorado Newsline reported. Advance Colorado backed that countermeasure.

Ballots are still being counted statewide, and the race has not been officially called.