Planning RSUs, ISOs, and NSOs together across tax years

At a mature tech company you often end up holding all three grant types at once: restricted stock units (RSUs) that vest on a schedule, incentive stock options (ISOs) from an earlier, lower strike, and non-qualified stock options (NSOs) layered on top. Each one is taxed differently, and the common mistake is to plan each in isolation. They are coupled. The income one grant throws off in a given year changes the tax on the others, and all three pile into the same single-stock position.

The grants are not three separate decisions. Income from any one of them moves the brackets and the AMT exposure for the other two.

Each grant type has its own lever

Before you can sequence them, you need to know what choice each grant actually gives you. The lever is different for each, which is exactly why they do not collapse into a single rule.

• RSUs are taxed as ordinary income at vest. On the vest date, the full market value of the shares is W-2 income, whether or not you sell. Your only real lever is what you do after vest: sell at vest and diversify, or hold and take on single-stock risk plus a future capital-gains decision. There is no timing choice on the income itself; the vesting schedule sets that.
• ISOs are timed around the AMT crossover. Exercising an ISO does not create ordinary income, but the bargain element (market price minus strike) is added to your alternative minimum tax (AMT) income in the exercise year. The lever is how many shares you exercise in each year, timed so you stay near your AMT crossover and then hold the shares toward long-term capital gains.
• NSOs are exercised around your ordinary brackets. When you exercise an NSO, the bargain element is immediately ordinary income, taxed like salary and subject to withholding. The lever is fitting that income into the bracket headroom you have left in a given year, rather than stacking a large exercise on top of an already high-income year.

Why they interact

Here is the coupling that makes a one-grant-at-a-time plan misleading. Every one of these levers feeds the same tax return, so pulling one changes the cost of the others.

• An RSU vest or an NSO exercise raises your ordinary income, which lifts your regular tax brackets and also lifts your AMT income base, shrinking the room you have to exercise ISOs before AMT kicks in.
• A large ISO exercise raises your AMT income, which can push you past the AMT exemption phaseout and change how much an additional NSO exercise or RSU sale actually costs in that year.
• All three add to the same concentrated single-stock position. Even if the tax math says hold, your total exposure to one company's stock may say sell. The tax-optimal share and the risk-optimal share are rarely the same number.

Plan any one grant as if the others did not exist and you will routinely overshoot the AMT crossover, waste bracket headroom, or quietly let your concentration drift past the level you would have chosen on purpose.

An order of operations for the year

You cannot optimize all three independently, but you can sequence them. A workable annual order of operations looks like this:

1. Take the RSU vests as they come. You do not control the timing of the income, so treat the vested value as the fixed ordinary-income floor for the year and plan everything else around it. The one open decision is sell-at-vest versus hold, which is mostly a concentration-and-conviction question, not a tax-timing one.
2. Time ISO exercises to the AMT crossover. With your ordinary income (salary plus RSU vests) now known, compute how many ISOs you can exercise before AMT starts adding tax, and exercise up to that crossover. Hold the shares toward the long-term capital-gains and qualifying-disposition windows. Carry the rest of the stack to next year, when the crossover resets.
3. Fit NSO exercises into the remaining bracket headroom. NSO exercises are ordinary income, so slot them into whatever room is left below the bracket you do not want to cross. In a year where RSU vests already filled the brackets, that headroom may be small, and the NSOs wait.
4. Trim concentration on a schedule. Set a target share of net worth for the single stock and sell down to it on a calendar, rather than reacting to the price. Selling RSU shares at vest, or qualifying-disposition ISO shares, both reduce concentration and each carries its own tax treatment.

Plan each piece with the free calculators

You can work each lever on its own numbers before you stitch them together. Three free calculators cover the individual pieces:

For the NSO side, the NSO Exercise Calculator shows the ordinary-income cost of an exercise and the bracket headroom it consumes, so you can see how much fits in a given year. For the RSU decision, the RSU Sell-vs-Hold Calculator compares selling at vest and diversifying against holding for a later capital-gains outcome. Each is free and needs no account.

Why integrated, multi-year planning is the hard part

The per-instrument calculators answer one decision cleanly. The thing they cannot do for you is the coupling: the right ISO exercise depends on this year's RSU vests and NSO exercises, which in turn depend on next year's crossover and your concentration target, across bullish, neutral, and bearish scenarios for the stock. That is a multi-position, multi-year problem, and the pieces move together.

Doing it by hand means iterating: pick an ISO amount, recompute the crossover after the RSU vest, check the NSO headroom, check concentration, then go back and adjust the ISO amount because the first pass was off. The pieces do not separate, so the loop does not converge in one pass.

Where to go from here

For the mechanics of each lever, the AMT crossover deep dive covers ISO timing and the multi-year credit, the NSO sell-vs-hold article covers the ordinary-income exercise decision, and the RSU withholding gap article covers the underwithholding most RSU holders hit at vest.