Missouri Amendment 5 Defeated: What Voters Rejected in 2026

Missouri Amendment 5, a GOP-backed measure on the August 4, 2026 primary ballot, was defeated by voters in a landslide. The amendment sought to eliminate the state income tax, a move that critics argued would shift the tax burden onto working families. The defeat was part of a broader rejection of GOP-backed amendments, including Amendment 4, which also failed. The outcome was reported by multiple Missouri news outlets, including KMBC, KSHB 41, and St. Louis Magazine. The Institute on Taxation and Economic Policy (ITEP) highlighted the potential negative impacts of such tax shifts, though it did not specifically analyze Amendment 5. The amendment's failure reflects voter sentiment against eliminating the income tax, with implications for state revenue and public services.

What Was Amendment 5?

Amendment 5 was a constitutional amendment placed on the August 2026 primary ballot by Republican lawmakers. Its core provision was simple: eliminate Missouri's state income tax. Supporters argued that removing the income tax would spur economic growth, attract businesses, and leave more money in the pockets of individuals and families. They framed the measure as a way to make Missouri more competitive with neighboring states that have no income tax.

Opponents, however, warned that the amendment would create a massive hole in the state budget. The income tax is a primary revenue source for Missouri, funding everything from public schools and highways to health care and public safety. Without it, the state would have to either cut services drastically or find new revenue from other taxes—likely sales or property taxes, which tend to hit lower- and middle-income families harder.

The Landslide Defeat

When the votes were counted, the amendment went down to defeat. KSHB 41 reported that Missouri voters "reject[ed] elimination of state income tax with failure of Amendment 5." The same outlet noted that Amendments 4 and 5 were both turned down during Tuesday's primary election. St. Louis Magazine echoed that sentiment, calling the amendments "GOP-backed" and noting their defeat.

The margin of defeat was significant enough that multiple outlets used the word "landslide." While exact percentages were not immediately available in the reports, the language suggests that the proposal was not merely rejected—it was overwhelmingly opposed. This is a notable outcome for a primary election, where turnout tends to be more partisan and where Republican voters might have been expected to support a tax-cut measure.

Why Did Voters Say No?

Several factors likely contributed to the amendment's failure. One key concern was the potential shift in the tax burden. The Institute on Taxation and Economic Policy (ITEP) has analyzed similar tax-cut proposals under the current federal administration, noting that "large tax cuts that primarily benefit the wealthy and corporations" can shift burdens onto working families. While ITEP did not specifically analyze Amendment 5, its general findings on tax policy under Trump-Republican leadership are instructive. The organization pointed out that such cuts often lead to higher taxes on consumption or reduced public services, both of which disproportionately affect those with lower incomes.

Missouri voters may have also been wary of the long-term consequences for public services. The state has faced budget challenges in recent years, and eliminating the income tax would have made those challenges far worse. Schools, roads, and public safety are all funded in part by income tax revenue, and voters may have decided that the risk to these services was too great.

Another factor could be the broader political climate. The 2026 primary came at a time when many voters are paying close attention to tax policy at the federal level. The Trump administration has enacted tax cuts that ITEP says "primarily benefit the wealthy and corporations," and voters may be growing skeptical of similar proposals at the state level. The defeat of Amendment 5, along with Amendment 4, suggests a mood of caution among Missouri Republicans.

What Happens Next?

With Amendment 5 defeated, Missouri's income tax remains in place. The state will continue to collect revenue from this source, and lawmakers will need to find other ways to address any tax reform goals they have. The defeat also sends a signal to other states considering similar measures: eliminating the income tax is a hard sell when voters understand the trade-offs.

For Missouri residents, the immediate impact is that their state income tax obligations remain unchanged. But the debate over tax policy is unlikely to disappear. Lawmakers who supported Amendment 5 may try again with a different approach, perhaps one that includes a replacement revenue source or a more gradual phase-out. Voters, meanwhile, have shown that they are paying attention to the details.

The outcome in Missouri is part of a larger conversation about tax policy across the country. As states grapple with budget shortfalls and competing priorities, the question of who pays for public services—and how—remains central. For more on tax policy, see ITEP's analysis of federal tax cuts. For local election coverage, refer to KMBC, KSHB 41, and St. Louis Magazine.

For now, Missouri has spoken. The income tax stays, and the state will have to find other ways to address the concerns that motivated Amendment 5. Whether that means targeted tax relief for low-income families or a broader overhaul of the tax code, the conversation is far from over. But the landslide defeat of Amendment 5 is a clear reminder that voters are skeptical of proposals that promise big benefits while hiding the costs.