Taxes take money from private individuals who generally know best how to spend it and put that money in the hands of politicians, who are less equipped to spend it wisely. So, raising taxes even further should require a strong consensus that it is absolutely necessary.

This is particularly true for income taxes. High income tax rates discourage productivity, work, investment, and economic growth. In effect, they are basically a penalty on earning income. That is why income tax increases should require more than a simple legislative majority.

Currently, 16 states have such supermajority requirements for tax increases. In November, Iowa voters will decide whether to join them. The constitutional amendment would require a two-thirds vote of the legislature to “increase the individual or corporate income tax rate or create a new income tax.”

Iowa has already experienced the consequences of high income-tax rates. The state once had one of the highest and most progressive income tax systems in the nation, with a top individual rate of 8.98% and nine brackets. At 12%, the top corporate income tax rate was once the highest in the nation.

Gov. Kim Reynolds understood that making Iowa’s economy more competitive required lowering those rates and expanding economic freedom. Since 2018, Reynolds and the legislature have enacted a series of reforms culminating in a 3.8% flat rate individual income tax in 2025, and a reduction in the top corporate rate to 7.1%.

Iowa’s reforms have made the Hawkeye state a leader in the nationwide flat tax revolution. That movement has been inspired, in part, by the work of one of this year’s two Nobel Prize in economics winners: Robert Hall. Fifteen states now have a single-rate income tax, and six adopted their flat tax within the past five years.

The alternative is the familiar “tax and spend” approach. Harry Hopkins, President Franklin D. Roosevelt’s Iowa-born advisor, described that philosophy as “tax and tax, spend and spend, elect and elect.” In recent years, states including Illinois, New York, Washington and California appear to be following that playbook, pursuing income tax increases to fund higher government spending.

In 2020, Illinois lawmakers put a measure on the ballot to replace the state’s 4.95% flat income tax with a graduated system reaching 7.99%. Fortunately, voters rejected it.In 2021, New York increased its top income tax rate from 8.82% to 10.9%. In March 2026, Washington lawmakers passed the state’s first income tax with a top rate of 9.9% on income over $1 million.In November 2026, California voters will consider measures to impose the nation’s first state-level wealth tax (on assets rather than income) and make temporary higher income tax rates on top earners permanent.

These tax increases are often driven by another problem: rapidly growing government spending. Washington State may be the poster child for this dynamic. Even before implementing an income tax, lawmakers in the Evergreen State had already hiked taxes on real estate transactions and financial institutions and created (and then increased!) a capital-gains tax. Even so, from 2013-2025 “spending grew 148%, outpacing revenue growth by 36% and population plus inflation by 77%.”

Washington’s experience illustrates a broader lesson. Rapid spending growth eventually creates pressure for politicians to raise taxes. With affordability already a top concern for many Iowans, raising income taxes would make the cost of living higher and raise the cost of doing business. Small businesses, which are the backbone of the economy, would be particularly hurt.

Reynolds put it plainly in January, “spending is what drives taxes—always has, always will. And the most reliable way to protect taxpayers is to limit the growth of government itself.”

A supermajority requirement would not make tax increases impossible. It would simply require broader agreement before legislators could increase Iowa’s income-tax burden. That gives taxpayers an important safeguard against the fiscal profligacy of politicians.

Unlike those in DC, state legislators must balance their budgets. The question is whether lawmakers will control spending or continually seek new revenue from taxpayers.

This November, Iowans can choose a constitutional protection that puts taxpayers first. Requiring a two-thirds legislative vote for income-tax increases would help preserve Iowa’s economic competitiveness, protect family budgets, and promote greater economic freedom for everyone in the state.