RSU tax estimator
A simple way to estimate the tax on a vesting year and the shortfall your withholding leaves behind. The interactive version is on the way.
RSUs · Forms & reporting
How much will a vesting year really cost you in tax? You can get close with one subtraction, and that estimate is usually all you need to avoid a surprise.
Interactive calculator coming soon
We are building the live estimator now. Until it ships, here is the math it runs, so you can do it by hand in a few minutes.
The math it runs
Vested value
Add the market value of every batch that vests this year. That is your RSU ordinary income.
Real tax owed
Multiply by your true marginal rate (federal plus state, plus any additional Medicare tax for high earners). For 2026 that additional Medicare tax is 0.9% 2026 on wages above $200,000 for single filers and $250,000 for married filing jointly.
Already withheld
Find what your employer withheld at vesting (often a flat supplemental rate, lower than your real rate).
The shortfall
Real tax owed minus already withheld. That is the amount to pay in estimated taxes, in the quarter the shares vest, to stay penalty-free.
What this means for you
The number that matters is the shortfall, not the headline tax. Run this once per vesting year and pay the gap on time. When the interactive tool lands, it will do this in one screen and flag the safe-harbor amount for you. For the reasoning, see the withholding gap.
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