NSO Exercise Tax Calculator (2026)

Non-qualified stock options (NSOs) create ordinary income — not capital gains — at the moment you exercise. The spread between your strike price and the current FMV is taxed like a paycheck: federal income tax, Social Security, Medicare, and state income tax all apply. This calculator estimates your total 2026 tax bill before you pull the trigger.

How NSO taxation works at exercise

When you exercise an NSO, IRC § 83 treats the entire spread — (FMV − strike price) × shares — as ordinary compensation income in the year of exercise. It doesn't matter what you do with the shares afterward: the tax clock starts the moment you exercise, not when you sell.

That ordinary income triggers three layers of federal tax, plus state:

1. Federal income tax at your marginal bracket. In 2026 the top rate is 37% (applies above $640,600 single / $768,600 MFJ). Because NSO income stacks on top of your salary, even a modest exercise can push you deeper into a higher bracket or eliminate deductions that phase out with income.
2. Social Security tax: 6.2% on wages up to the 2026 SS wage base of $184,500.¹ If your salary already exceeds $184,500, no additional SS tax applies to the NSO exercise — a meaningful saving. If you exercise early in the year before reaching the cap, SS applies to the full spread.
3. Medicare tax: 1.45% on all wages with no cap, plus the 0.9% Additional Medicare Tax on wages above $200,000 (single) or $250,000 (MFJ).²

Cashless vs. exercise and hold: same tax, different cash flow

Here's the key insight: you owe the same ordinary income tax at exercise regardless of whether you sell the shares or hold them. The decision between cashless and hold is purely about what you want to do with the stock after paying that tax bill.

Cashless exercise (sell immediately)

You simultaneously exercise and sell all shares at the current FMV. Your employer's equity platform handles the mechanics — you receive the spread minus taxes as cash. Your cost basis for the brief share ownership is FMV at exercise (per IRC § 83), so the immediate sale creates zero additional gain. Net proceeds = bargain element − total tax.

Exercise and hold

You pay the strike price in cash, keep the shares, and owe the tax bill separately (via employer withholding or estimated payments). Your new cost basis = FMV at exercise. If you hold the shares for more than 12 months and sell at a higher price, any appreciation above that FMV is taxed at long-term capital gains rates — 0%, 15%, or 20% federal depending on your income — rather than ordinary income rates. The exercise-day tax is the same either way; you're betting on additional appreciation.

Four NSO exercise strategies

• Cashless (sell everything): Simplest. You net the after-tax spread as cash. No ongoing concentration risk. Most appropriate when you need liquidity or don't have conviction in the stock at current prices.
• Sell to cover (net exercise): Sell enough shares to cover the strike price and withholding; keep the rest. Maintains some upside exposure without requiring out-of-pocket cash beyond what the shares themselves generate.
• Cash exercise and hold all: Pay strike price and estimated tax out of pocket; keep all shares. Maximum upside exposure, maximum cash requirement, maximum concentration risk. Appropriate when you have high conviction in the stock and sufficient liquidity elsewhere.
• Spread the exercise over years: Exercise tranches over multiple tax years to limit how much bargain element stacks on top of salary in any single year. Reduces peak bracket exposure, but requires ongoing management and extends timeline — particularly important if options expire in pieces.

State tax traps with NSOs

If you've moved states between the grant date and exercise date, multiple states may claim tax on the same spread. California uses a workday-allocation formula (FTB Publication 1100): the portion of the bargain element taxable to California equals the spread times the ratio of California workdays during the grant-to-exercise period over total workdays. A software engineer who granted NSOs while at a California office, moved to Texas three years later, and exercises today may owe California tax on the majority of the spread despite living in Texas.

New York applies its convenience-of-employer rule (TSB-M-07(7)I): employees working for a New York employer may owe New York tax on NSO exercises even after relocating, unless their remote work arrangement satisfies the "necessity" test. The calculator above uses only your current state's top rate — if you've relocated, your actual exposure may be higher.

Post-termination NSO window

Unlike ISOs — which lose ISO status after 90 days of leaving an employer (IRC § 422(a)(2)) — NSO exercise rights are governed entirely by your option agreement, not by statute. Many agreements give former employees 30 days, 90 days, 1 year, or the full original expiration date to exercise. Read your plan document carefully.

Letting in-the-money NSOs expire is pure economic loss. Even after paying the ordinary income tax at exercise, you capture the after-tax spread that you would otherwise forfeit. The only rational case for not exercising an expiring in-the-money NSO is genuine belief that the company's equity value will fall below the strike price before you can sell.