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.
