Colorado’s income tax structure has been fixed at a flat rate for decades, a product of the state’s Taxpayer’s Bill of Rights framework and a series of past ballot decisions. The current flat rate applies uniformly regardless of how much a filer earns—a setup that supporters say is simple and predictable, and that critics argue favors higher earners.
The dueling campaigns
Now two separate groups are pushing rival November ballot measures that would take the state’s tax code in opposite directions. One campaign is working to lock in or further entrench the flat tax model; the other wants Colorado voters to approve a graduated income tax—one that would charge higher rates on higher earners. Both are targeting the November 2026 election, setting up a direct clash at the ballot box.
The effort pits competing visions of tax fairness against each other, and it isn’t clear yet which measure—if either—will clear the signature and legal hurdles required to reach voters. Colorado ballot initiative campaigns frequently stall before qualifying; the path from petition drive to certified measure is long, and both sides are still working through that process.
A graduated income tax has failed before in Colorado. Voters rejected a similar proposal in 2020—Proposition 116 passed in the same cycle, actually cutting the flat rate slightly—so backers of the graduated approach face a track record they’ll need to overcome. Opponents of a graduated structure argue that changing the tax code mid-recession or during economic uncertainty is a particular risk for a state that depends heavily on income tax revenue.
Colorado Politics reported on the competing campaigns June 11, 2026. Neither group had disclosed full funding details as of that report, and no official ballot language had been certified.
Reported by Colorado Politics, published June 11, 2026. Read the original report.
