V VestedGrant
Idaho · nso state

NSO exercises and state tax in Idaho

NSO spread is ordinary wage income at exercise; Idaho takes 5.8% of that at the top bracket, plus its share of any later capital gain on sale.

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.

Ordinary income at exercise

NSO spread (FMV minus strike at exercise, times shares) is ordinary wage income in the year of exercise. Idaho taxes it at up to 5.8%, stacked on your base wages. Federal supplemental withholding applies at 22% (or 37%), just like RSUs.

Cash outlay vs tax

NSO exercise requires cash for the strike price plus tax withholding. Cashless exercise (same-day sell) nets out the cash requirement but converts the full spread to ordinary income in the exercise year. Early exercise with 83(b) is available on pre-vesting NSOs at some companies; it starts the long-term capital gain clock on the full share value going forward.

Interaction with later sales

After exercise, your basis equals strike plus spread (the amount taxed as ordinary). Further price appreciation is capital gain on sale, split long-term vs short-term at the one-year mark. For Idaho residents, this is where the state savings from holding (limited, since Idaho taxes LTCG as ordinary) matter most.

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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