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Montana · capital gains

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

Montana offers preferential treatment of long-term capital gains. We show how that interacts with RSU cost basis and ISO qualifying dispositions.

What Montana residents actually pay

Montana taxes ordinary income at a top marginal rate of 5.9%. 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.

Partial capital-gains credit.

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.

Montana gives preferential treatment to long-term capital gains — the specifics vary, but it can meaningfully reduce your state bill on a concentrated sale. Check current-year rules; preferential treatment has changed in several states over the past five years.

Frequently asked

Does Montana tax RSU income the same as wages?
Yes. Montana treats RSU ordinary income as wages, taxable at the state's top marginal rate of 5.9%. 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 Montana?
Montana 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 Montana 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 Montana move, expect the old state to tax the portion of each tranche attributable to workdays earned there. Montana taxes the remainder.
Can I reduce Montana taxes by timing my RSU sales?
Montana gives preferential treatment to long-term capital gains. Holding RSU shares 12+ months past vest can produce both federal and state savings. Weigh concentration risk before using this as a reason to hold.

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