West County residents earning six figures stand to pocket thousands if Missouri's individual income tax disappears. They'd also pay sales tax on their lawyers, their landscapers, and, if future lawmakers choose to tax it, their kids' daycare.

That's the trade-off at the center of Amendment 5, which goes before voters on Tuesday, Aug. 4. The constitutional amendment would require lawmakers to phase out the state's top marginal income tax rate of 4.7% entirely over five years, replacing the lost revenue by expanding sales taxes to services and transactions that are currently exempt.

Rep. Ben Keathley, the Chesterfield Republican who represents House District 101 and helped shepherd the measure through the General Assembly, frames it as a guaranteed raise. "Every worker in Missouri would automatically get a 4.7% salary increase," Keathley told West Newsmagazine in a June 14 interview. Missouri's income tax is graduated, though, and 4.7% is the top marginal rate. Most workers' effective state tax rate is lower, meaning the actual take-home bump would vary.

Keathley, an attorney with offices in Chesterfield and Clayton who has served on the Chesterfield City Council since 2017, argued the amendment doesn't raise taxes on its own. It authorizes lawmakers to close what he calls sales tax loopholes on services like legal work, accounting, and home renovation. He contended those expanded taxes would hit higher earners hardest because lower-income residents don't typically hire accountants, contractors, or lawn-care services.

The revenue triggers built into the amendment are the linchpin of Keathley's case. Income tax rates can only drop when state revenue grows enough to absorb the cut. "We've been cutting the income tax and have not lost revenue," he said.

The opposition math

Critics say the math doesn't work that cleanly.

Missouri collected between $8.5 billion and $9.2 billion in individual income tax last fiscal year, depending on the source and methodology, representing roughly 65% of state general revenue. To replace that without broadening the sales tax base, the state's 3% general revenue sales tax rate would need to climb to as high as 11.5%, according to the Western District Court of Appeals ruling that revised the ballot language in June.

The nonpartisan Missouri Budget Project puts the combined state-and-local sales tax rate at 16% under a full replacement scenario and estimates 80% of Missourians would see a net tax increase. A household earning the state median of $65,400 would pay roughly $535 more per year, the group calculates.

Scott Charton, spokesman for Missourians for Fair Taxation, the opposition campaign backed by a $1.9 million contribution from the Missouri Association of Realtors, said the amendment strips constitutional guardrails voters previously approved. Amendment 5 would override the 1980 Hancock Amendment, which requires voter approval before the state can enact major tax increases, along with a 2010 ban on real estate transfer taxes and a 2016 prohibition on new sales taxes on services.

"It gives them an open checkbook without those constitutional guardrails," Charton said.

He added that retirees and low-wage workers who already pay no income tax would still face higher sales taxes on everyday goods under the new structure.

A $1.7 billion backdrop

The ballot question lands amid a fiscal reckoning. State Auditor Scott Fitzpatrick warned on June 10 that Missouri's current budget produces a $1.7 billion spending deficit for fiscal year 2027. The state's general revenue balance, which peaked at $5.8 billion in FY2023, is projected to fall to $600 million by the end of FY2027 and run dry early in FY2028.

Gov. Mike Kehoe, who placed Amendment 5 on the August ballot and made it his top legislative priority, acknowledged the budget strain but drew a different conclusion. "We don't have a revenue problem, we have a spending problem," Kehoe said on June 15, noting the state added more than 3,420 budget items over five years at a cost exceeding $12.7 billion.

Kehoe maintained the income tax should still go, arguing Missourians can spend their own money better than government can.

What West County residents face

For Chesterfield, Wildwood, and Ballwin households, the stakes cut both ways. Higher earners would see the largest absolute savings from eliminating the income tax. But they'd also face the broadest new exposure to sales taxes on professional services they already use: estate planning, HVAC repairs, and veterinary visits.

The amendment does not specify which services would become taxable or lock in existing exemptions for groceries, prescription drugs, or residential utilities. Those decisions would fall to future legislatures.

The Missouri Supreme Court declined on June 8 to alter the court-approved ballot language, which tells voters Amendment 5 would "curtail constitutional limits on taxing goods and services."

Voter registration for the Aug. 4 election closes July 8.