The Kansas Experiment, and Why Missouri’s Version Can’t Be Undone

• We don’t have to guess whether big income tax cuts pay for themselves. Kansas ran the experiment next door. We can see what happened.
• What Kansas did: In 2012–13, Governor Brownback cut income taxes deeply, promising growth would replace the money. It didn’t. Revenue collapsed, budgets were cut repeatedly, the state’s credit was downgraded, and in 2015 schools were cut across the board.
• How it ended: In June 2017, the Republican-led legislature repealed most of the cuts — over the governor’s veto. They declared the experiment a failure.
• How Missouri compares: Some of the same advisers are involved, and the growth promise is the same. In fairness, Missouri’s plan is a swap (it can raise sales taxes to backfill) and is phased in gradually — more cautious than Kansas’s all-at-once cut.
• Why Missouri’s could be worse: Kansas’s saving grace was that it could undo the mistake with a simple law. Amendment 5 writes income-tax elimination into the constitution — reversing it would require a whole new statewide vote. The escape hatch Kansas used wouldn’t exist.
• Two more risks: Missouri leans even harder on its income tax (~two-thirds of revenue) and lacks the tourism- or resource-driven tax base some no-income-tax states rely on. And Kansas only cut rates — Missouri proposes full elimination, a more extreme version.
• Bottom line: same failed growth bet, minus the ability to undo it.

The Full Story: Neighbor comparison + irreversibility

When people argue about whether big income tax cuts grow the economy, it usually comes down to dueling predictions. But on this question, we have something rare: a real-world test, right next door. Kansas tried it. We can look at what happened.

What Kansas did

In 2012 and 2013, under Governor Sam Brownback, Kansas cut its income taxes deeply — dropping the top rate by almost 30% (from 6.45% toward 4.6%) and zeroing out the tax on many business owners’ pass-through income.¹ The promise was familiar: the cuts would spark so much growth that the economy would more than make up for the lost revenue. One analysis called it one of the cleanest real-world tests of supply-side tax cuts ever run.²

The growth didn’t show up. Instead, revenue collapsed. Kansas faced repeated budget shortfalls, made round after round of mid-year cuts, and had its bond rating downgraded.³ In 2015, the state cut public school funding across the board by 1.5% — about $44.5 million — to help plug the hole, and the state’s courts separately found school funding inadequate under the state constitution.⁴ The promised job growth lagged behind neighboring states and the nation.⁵

How Missouri’s plan compares

The similarities are striking. Some of the same economists and low-tax advocates who advised Brownback have also advised Missouri’s income-tax-elimination effort.⁷ And the core promise — cut the income tax, growth will replace the money — is the same bet Kansas made and lost.

But the plans aren’t identical, and it’s only fair to note the differences. Missouri’s plan is a swap, not just a cut — it pairs ending the income tax with authority to raise sales taxes to backfill. And it’s phased in based on revenue growth, rather than enacted all at once like Kansas.⁸ Supporters will point to that gradual design as the lesson learned from Kansas, and that’s a fair point as far as it goes.

Why Missouri’s version could be worse

Here’s the catch, and it’s the most important part. Kansas’s saving grace was that it could undo its mistake. When the cuts failed, lawmakers simply passed a new law and restored the taxes. That escape hatch is what ended the damage.

Missouri’s plan would close that hatch. Amendment 5 would write the elimination of the income tax into the state constitution. Once the income tax is gone, bringing it back wouldn’t be a simple vote in the legislature. It would take a whole new constitutional amendment — another statewide public vote.⁹ If Missouri’s version fell short the way Kansas’s did, the easy fix Kansas used wouldn’t be available.

Two other things make Missouri’s bet riskier. Missouri leans even more heavily on its income tax than Kansas did — about two-thirds of general revenue — and it doesn’t have the tourism- or natural-resource-driven tax base that helps some no-income-tax states get by.¹⁰ And one more distinction worth keeping straight: Kansas cut its income tax rates but never eliminated the tax entirely. Missouri is proposing full elimination. In that sense, Missouri’s plan is a more extreme version of the experiment that already happened next door.