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Idaho · capital gains

Capital gains tax in Idaho: long-term vs short-term, RSU sale edge cases

Idaho taxes long-term gains at the same rate as ordinary income. Here's what that means for tender offers, RSU sales, and ISO dispositions.

What Idaho residents actually pay

Idaho taxes ordinary income at a top marginal rate of 5.8%. 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 5.8% state tax as of 2023.

Long-term vs short-term treatment

Federal long-term rates cap at 20% (plus 3.8% NIIT for high earners) on gains held 12+ months past the basis-setting event. For RSUs, the basis-setting event is the vest date. For ISOs held through a qualifying disposition, the rules are stricter: two years from grant and one year from exercise.

Frequently asked

Does Idaho tax RSU income the same as wages?
Yes. Idaho treats RSU ordinary income as wages, taxable at the state's top marginal rate of 5.8%. 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 Idaho?
Idaho 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 Idaho 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 Idaho move, expect the old state to tax the portion of each tranche attributable to workdays earned there. Idaho taxes the remainder.
Can I reduce Idaho taxes by timing my RSU sales?
Idaho 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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