A Cole County circuit judge ruled Monday that a Missouri constitutional amendment to phase out the state’s individual income tax and replace it with broader sales taxes will appear on the August 4 primary ballot as Amendment 5 — clearing a significant legal hurdle for one of Gov. Mike Kehoe’s top policy priorities.
Circuit Judge Christopher Limbaugh rejected arguments from opponents who contended the measure ran afoul of constitutional rules limiting amendments to changes within a single article and a single subject. Within hours of the ruling, opponents filed an appeal seeking to overturn it.
What the Amendment Would Do
If voters approve Amendment 5, the state legislature would be directed to establish revenue benchmarks that trigger reductions in Missouri’s top individual income tax rate, currently set at 4.7% for taxable income above approximately $9,200. Lawmakers would have five years to either expand the range of transactions subject to sales tax or raise the existing rate — currently 3% — to generate enough revenue to offset what the income tax brings in.
The amendment does not specify the revenue triggers. Should the legislature choose not to extend sales tax coverage to additional transactions, state officials estimate the current sales tax rate would need to climb as high as 11.5% to fully replace income tax revenue.
Kehoe first called for the change during his January 13 State of the State address, making it the centerpiece of his fiscal agenda this year.
The Court Challenge
Opponents argued the proposal impermissibly spanned multiple constitutional articles by using the word “notwithstanding” to override other provisions, and that addressing both income and sales taxes — along with local tax directives — violated the single-subject requirement.
Judge Limbaugh was unconvinced on both counts. The provisions all fit within “the elimination of the state individual income tax through a coordinated restructuring of state and local taxation,” he wrote, and he was unable to identify any constitutional section the measure impermissibly altered.
On the question of ballot language, Limbaugh found the descriptions prepared by the General Assembly and the secretary of state’s office met the legal standard of being unbiased and sufficient. The legal questions surrounding the measure must be fully resolved by June 9, when appeals arguments are expected.
By the Numbers
$2 million — Donations already raised by Missouri Promise, a not-for-profit supporting the amendment
4.7% — Current top individual income tax rate, applying to incomes above roughly $9,200
3% — Current state sales tax rate, which could rise to as much as 11.5% without expanded coverage
5 years — Time lawmakers would have to restructure sales tax law under the amendment’s framework
June 9 — Deadline for all legal challenges to be resolved before the August ballot is finalized
Campaign Lines Forming
Amendment 5 is shaping up to be among the most financially contested ballot measures in Missouri this cycle. Two opposition campaigns have organized against it: Missourians for Fair Taxation, led by the Missouri Association of Realtors and focused on building business opposition, and No Everything Tax, which is mobilizing opposition from the political left.
Attorney General Catherine Hanaway, who defended the measure, said the ruling “allows voters to decide the future of tax policy in our state.” Chuck Hatfield, the attorney representing the plaintiffs, said lawmakers “failed to tell voters the truth” and characterized the amendment as enabling the largest sales tax expansion in state history while weakening constitutional taxpayer protections.
Zoom Out
Missouri’s push to eliminate the income tax mirrors similar efforts in other states looking to shift from income-based to consumption-based tax systems. The debate touches on broader questions about tax structure, economic competitiveness, and the distribution of the tax burden — concerns that have also surfaced in Missouri’s ongoing disputes over property tax assessments. Missouri lawmakers earlier this session struggled to deliver property tax relief amid rising assessments, adding to the fiscal tensions surrounding Amendment 5.
What’s Next
With the appeal now pending, Missouri courts face a tight window to resolve all remaining legal questions before the June 9 deadline. If the amendment survives appeal, Missouri voters will decide in August whether to direct the legislature to begin unwinding the state income tax — a decision that could reshape state and local revenue systems for decades.