In Colorado, signatures were submitted to the secretary of state on July 15, 2026, for a ballot initiative to cap individual and corporate income tax rates at 4.4% of a taxpayer's federal taxable income.
The Colorado secretary of state's office has until Sept. 2, 2026, to review the signatures to determine whether the petition contains at least 124,238 valid signatures, thereby meeting the minimum requirement to be placed on the ballot for Nov. 3, 2026.
As of 2026, Colorado has a flat income tax rate — set at 4.4% — which applies to all taxpayers at the same rate, regardless of income. While the initiative would not lower rates, the Colorado Taxpayer's Bill of Rights (TABOR) would still require voter approval to raise them, regardless of whether the initiative is approved. Because Initiative 232 is an initiated state statute, the legislature could amend or repeal the 4.4% cap. However, doing so would not itself authorize an income tax rate increase, which would continue to require voter approval under TABOR.
The measure — known as Initiative 232 — was filed on Feb. 20, 2026, as an combined initiated constitutional amendment and state statute, which amends both the Colorado Constitution and the Colorado Revised Statutes. Initiative 232 is supported by Advance Colorado, an organization that describes its mission as "[pushing] back on the progressive policies that have put our state on the wrong track."
Opposing Initiative 232, the organization Protect Colorado's Future has been gathering signatures for a separate measure — known as Initiative 195 — to establish a graduated income tax, which would require individuals and businesses to be taxed based on their income. Additionally, the initiative would remove TABOR's uniform tax rate requirement.
Speaking in support of Initiative 195, Kathy White, the executive director of the Colorado Fiscal Institute, said, "[working families] shouldn’t have to pick up the tab so the wealthiest get a $71,000-a-year gift from Congress — especially when TABOR has already tied our hands for decades.” Protect Colorado's Future has not submitted its signatures to the Colorado secretary of state's office, but has until Aug. 3, 2026, to do so.
Since Initiative 232 and Initiative 195 conflict with one another — with the former prohibiting individual and corporate income tax rates above 4.4%, and the latter establishing rates above 4.4% for certain income brackets — if both measures qualify for the ballot and are approved, the conflicting provisions of whichever measure receives more votes would take effect. According to the Colorado Revised Statutes, "In the case of adoption of conflicting provisions, the one that receives the greatest number of affirmative votes prevails in all particulars as to which there is a conflict." Michael Fields, the executive director of Advance Colorado, said, "This is a clear counter to the far left’s attempt to hike taxes in Colorado, price people out of the state we love, and drive business out. We’ll always fight to protect TABOR and keep our taxes low", and said that, if both passed, the measure receiving more affirmative votes would govern.
Additionally, because Initiative 195 amends both the state constitution and state statutes, the provision removing the constitutional requirement for a uniform tax rate could still possibly take effect if both initiatives are approved by voters. This would mean that, while the 4.4% rate cap would be implemented, there would no longer be a constitutional requirement for a flat tax rate.
The last time voters decided on a statewide ballot measure related to income tax rates in Colorado was in 2018. On Nov. 6, 2018, voters in the state considered Amendment 73, which would have established an income tax bracket system rather than a flat income tax rate, raised taxes for individuals earning more than $150,000 per year, raised the corporate income tax rate, and created the Quality Public Education Fund. Amendment 73 was defeated by voters, with 53.57% of the vote against it.
In previous years, Advance Colorado filed and gathered signatures for measures in policy areas such as taxes, law enforcement, and education. In 2024, the organization filed and gathered signatures for three ballot measures related to a right to school choice, parole eligibility for persons convicted of certain violent crimes, and funding for law enforcement training and benefits for the families of deceased first responders, with two of these measures being approved and one being rejected by voters.
For the Nov. 3, 2026, ballot, Advance Colorado filed and gathered signatures for three additional measures: Initiative 85, Initiative 95, and Initiative 177. Initiatives 85 and 95 were certified for the ballot, and signatures for Initiative 177 were submitted for review on June 24, 2026.
Initiative 85 would increase the penalties for the manufacturing, sale, and possession of fentanyl, as well as require court-mandated treatment for certain types of felonies for possessing fentanyl, and remove drug possession exemptions in determining whether an individual is considered a habitual criminal. Initiative 95 would require state and local law enforcement to notify the U.S. Department of Homeland Security within 72 hours after charging an individual when they are not lawfully present in the United States or their immigration status cannot be determined after a reasonable effort by officers, and the individual is charged with a violent crime or has a prior felony conviction on their record. Initiative 177 would establish the right for consumers to purchase natural gas for cooking or heating in homes or businesses, as well as for distributors and utilities to sell natural gas.
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