Coloradans will again vote on a long list of statewide ballot measures in 2026 — but unlike in previous years, the state Legislature had hardly anything to do with it.

Proposition NN, which asks voters to raise the cap on the amount of tax revenue the state is allowed to keep each year, is the only legislatively referred measure on Colorado’s ballot this year. Democratic majorities in the General Assembly referred it to voters in May.

That’s a departure from the recent trend. Lawmakers referred seven questions to the ballot in 2024, and have averaged about five in every even-year election since 2016.

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The Legislature’s lone referendum this year comes amid a flood of initiatives that were placed on the ballot by citizen groups who gathered the required number of petition signatures. Proposition NN will appear on ballots sandwiched between 13 initiated constitutional amendments and statutory propositions — including six from Advance Colorado, a right-wing “dark money” group that doesn’t disclose its donors.

14 measures will appear on Colorado’s statewide ballot in 2026

If approved, Proposition NN would raise the revenue cap established by the Taxpayer’s Bill of Rights, a 1992 constitutional amendment that placed strict limits on the state’s taxing and spending authority. Nonpartisan state analysts estimate the higher cap would increase funding for K-12 education by about $500 million a year. Depending on trends in revenue growth in future years, it could reduce the amount returned to taxpayers as TABOR refunds.

The measure sailed through the Legislature this year on mostly party-line votes, with nearly all Democrats in favor and Republicans unanimously opposed. It’s backed by the Colorado Education Association, the state’s top teachers union.

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“Colorado’s public schools have been underfunded for decades because we are operating under an outdated revenue cap written more than 30 years ago,” CEA president Kevin Vick said earlier this year. “This measure does not raise taxes or ask Coloradans to pay a dollar more. It simply allows the state to use the revenue it already collects to support students, educators, and communities across Colorado.”

Yes For Colorado Kids, an issue committee registered in support of Proposition NN, had reported just under $2 million in campaign contributions as of September 1. About half of that total came from Gary Advocacy, an arm of philanthropic group Gary Community Ventures, with the other half coming from a CEA-associated nonprofit and local Colorado teachers unions.

Two other tax measures

Proposition NN is one of three tax-related measures on the 2026 ballot — and if two or more of those measures are approved, things might get complicated.

The Protect Colorado’s Future campaign, led by liberal advocacy groups including the Bell Policy Center and the Colorado Fiscal Institute, is behind Amendment 87, a graduated income tax measure. The amendment asks voters to approve a new tiered income tax system, under which Coloradans earning over $500,000 a year — the top 3% of earners — would pay higher rates, with those in lower brackets receiving a slight tax cut.

Colorado’s public schools have been underfunded for decades because we are operating under an outdated revenue cap written more than 30 years ago.

– Kevin Vick, CEA president

Dozens of liberal and progressive groups have endorsed both Amendment 87 and Proposition NN. The passage of both measures would represent by far the biggest set of changes to TABOR in the 34 years since Colorado voters approved it.

A long list of pro-TABOR conservative groups, meanwhile, are opposed to both measures. Advance Colorado says Proposition NN “undermines the purpose of TABOR, which was designed to limit government growth,” and it questions the need for additional K-12 education funding amid declining enrollment.

“This proposed measure is yet another route the Legislature has taken to circumvent TABOR and retain revenue for their own spending purposes,” the Advance Colorado Institute wrote in a report earlier this year. “TABOR refunds are a unique feature of Colorado that have historically provided significant relief to households across the state, and voters continue to strongly support these safeguards.”

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Advance Colorado is also bankrolling a counter-proposal to block the graduated income tax: Proposition 136, which would cap income tax rates and prevent Amendment 87’s higher rates on higher incomes from going into effect.

Under Colorado law, any potential conflicts between two or more enacted ballot measures are resolved according to which measure got the most yes votes.

At least four campaign committees — Let’s Go Colorado, Brighter Colorado, Affordable Colorado and Don’t Price Us Out — have registered in opposition to both Proposition NN and Amendment 87. As of September 1, Brighter Colorado had reported about $275,000 in donations, nearly all of which came from Advance Colorado and another conservative “dark money” group, Common Sense America.

Ballots will be mailed to Colorado voters beginning October 2.