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Kentucky · 401k state-tax

401(k) and retirement accounts in Kentucky: state deduction and Roth considerations

Traditional 401(k) contributions reduce Kentucky taxable income today at 4% marginal. Roth 401(k) reverses the math. For equity earners, the state-tax dimension often flips the right answer.

What Kentucky residents actually pay

Kentucky taxes ordinary income at a top marginal rate of 4%. RSU settlement value, NSO exercise spread, and ESPP discount income all count as ordinary wages for this purpose and flow through the state's normal brackets.

Flat 4%; further reductions tied to triggers.

Traditional 401(k) in Kentucky

A pre-tax 401(k) contribution reduces both federal and Kentucky taxable income today. At the top bracket, every $1,000 contributed saves 39.0 cents on the dollar (federal 35% + state 4%). At retirement, withdrawals are taxed at your then-current bracket.

Roth 401(k) breakeven

Roth 401(k) contributions are taxed at today's rates; withdrawals are tax-free. The Roth choice beats traditional when your retirement bracket is higher than your contribution bracket. For equity earners in high-income years, traditional is usually right during big RSU years and Roth is right during low-income transition years.

Mega-backdoor Roth

After-tax 401(k) contributions above the standard $23,500 limit can be converted to Roth in plans that allow it. For high earners in Kentucky, this is the largest tax-advantaged bucket available after the primary 401(k) and IRA caps. Check whether your plan allows after-tax contributions and in-plan Roth conversions.

Frequently asked

Does Kentucky tax RSU income the same as wages?
Yes. Kentucky treats RSU ordinary income as wages, taxable at the state's top marginal rate of 4%. Supplemental-wage federal withholding (22%, or 37% above $1M YTD) does not adjust for state withholding, so you often owe extra at filing.
What happens if I exercise ISOs while living in Kentucky?
Kentucky does not run a separate state AMT, so only federal AMT applies. You still need to model the bargain element carefully if you plan a cashless exercise-and-sell.
I moved to Kentucky from another state. Who taxes my vesting RSUs?
Most high-tax states (CA, NY, MA) source RSU ordinary income to workdays between grant and vest. If your grant pre-dates your Kentucky move, expect the old state to tax the portion of each tranche attributable to workdays earned there. Kentucky taxes the remainder.
Can I reduce Kentucky taxes by timing my RSU sales?
Kentucky taxes long-term capital gains at the same rate as ordinary income, so timing alone does not produce a state savings — only federal. Holding for 12 months still halves the federal rate on gains above basis.

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