A pitch to shore up Colorado’s Medicaid program and schools by ramping up taxes on the state’s wealthiest residents will likely go to voters next year under a proposal announced Wednesday morning by a coalition of progressive groups.

The proposed ballot measure would end Colorado’s decades-old flat income tax policy and require those making more money to pay higher rates. The measure, if approved by voters in November 2026, would cut the effective income tax rate for individuals making less than $506,000 — while raising the effective tax rate for those above that threshold.

The changes would generate another $2.3 billion per year for the state, according to an analysis by the initiative’s backers. And the proposal would break a key piece of the Taxpayers’ Bill of Rights, or TABOR, the longstanding state constitutional amendment that governs state tax policy.

TABOR, among other things, requires the state to have the same income tax rate for all residents, regardless of income. Colorado is one of 15 states with a flat tax, while 27 others plus the District of Columbia tax higher-income residents at a higher rate than lower-income residents pay.

Read more from Nick Coltrain and Seth Klamann at DenverPost.com.