Colorado's Amendment 87 Raises the Average Tax Bill Only for 46,328 Filers Above $1 Million

If voters approve Amendment 87 on November 3, Colorado's flat 4.4 percent income tax splits into six brackets starting in tax year 2027. In the Legislative Council's own table, exactly one income group sees its average bill rise. That group is the 46,328 taxpayers reporting $1 million or more in federal adjusted gross income, who would owe $26,085 more on average.

What the bracket table does to each income group

The 2026 State Ballot Information Booklet sorts taxpayers by federal adjusted gross income in its Table 3. Every group below $500,000 gets a cut that grows with income until it caps at $325, reached at $150,000. The roughly 55,900 taxpayers between $500,000 and $999,999 still see an average cut of $284, because only income above $500,000 is taxed at the higher 7.4 or 7.9 percent rates.

The table does not reconcile with the headline revenue figure. Adding its rows gives a net increase of about $636 million, against the $1.972 billion the booklet projects for 2027-28, and the booklet does not say whether business returns explain the gap. The $2.7 billion ceiling is a forecast-error margin, about 11 percent of the $24.62 billion in state spending projected for that year without the measure.

The brackets are not adjusted for inflation, so more income falls into the higher rates over time. The new money goes into a Colorado Future's Account, exempt from the TABOR revenue limit, and must add to existing spending on K-12 education, health care and early childhood care rather than replace it.

Both sides on the $2.7 billion

“It's more that principle that is the problem with Amendment 87, giving the government a $2.7 billion blank check at a time when Colorado is already extremely unaffordable.”

Advance Colorado sponsors Proposition 136, which would cap the rate at 4.4 percent. Brown also argues the amendment was drafted to remove constitutional language rather than add it, avoiding the 55 percent threshold for new text. The booklet lists Amendment 87 as passing with a simple majority. Tamara Pogue, a Summit County commissioner on the steering committee of the coalition behind the measure, called the blank check label disingenuous because the revenue is tied to named purposes and an annual audit.

“We're either going to cut healthcare for older adults or we're going to bring in new revenue.”

If both measures pass, the booklet says the exact outcome is unclear, because Amendment 87's rates above $500,000 exceed the 4.4 percent limit in Proposition 136. The legislature or a court would have to resolve the conflict. Each campaign is telling voters to check yes on its measure and no on the other, and nothing stops a voter from checking yes on both.

Do top earners actually leave

Opponents say they do. The booklet's argument against warns the rates "may encourage some high earners to leave the state entirely." One Denver tax attorney told the Colorado Sun that some wealthy clients are already moving their addresses, driver's licenses and voter registrations to Florida. She was not named, and no client count is given.

Massachusetts is the nearest test. In 2022 voters added a 4 percent surtax on household income above about $1.1 million, taking the top rate from 5 to 9 percent. Colorado's top bracket rises by 4.0 points, from 4.4 to 8.4 percent. The Massachusetts Department of Revenue reported that the surtax brought in $3,380,320,213.11 in the fiscal year ending June 30, 2026, according to WBUR. That is up from $2.987 billion the year before and well above the department's original $1.2 billion annual estimate.

The migration data cuts both ways. Bloomberg, citing IRS figures summarized by the Massachusetts Budget and Policy Center, reported that people leaving Massachusetts took a net $4.2 billion in adjusted gross income in 2023, up 8 percent. A Boston Globe analysis cited by the Colorado Sun found nearly 30,000 more people left than arrived between 2022 and 2023, and more than 70 percent of that net loss came from people earning under $200,000. Neither figure isolates filers above $1 million. A Boston Globe headline listed on the budget center's site calls the evidence "new data, but still no clear answer."

Cristobal Young, a Cornell sociologist who studies tax-driven migration, found no widespread exodus after top-rate increases in New Jersey, New York and California. "Moving to another state is the most difficult of all things you can contemplate to reduce your tax burden," he told the Colorado Sun. Jim Rooney, president of the Boston Chamber of Commerce, campaigned against the surtax and says it is too soon to judge, because IRS data cannot show who decided not to move there.

Ballots were mailed October 2 through 9. Attorney General Phil Weiser told the Colorado Sun he cannot weigh in on Amendment 87 because of active litigation over the measure, and this report did not review those court filings.