Equity comp
Why your RSUs are under-withheld
When restricted stock units vest, the IRS treats the full market value as supplemental wages — ordinary income, exactly like a bonus. Your employer typically withholds federal tax at the flat 22% supplemental rate (rising to 37% on amounts over $1 million in a year). The problem: if your salary already puts you in the 24%, 32% or 35% bracket, 22% withholding isn't enough, and you owe the difference in April.
The three taxes on every vest
1. Federal income tax at your marginal rate. 2. FICA — 1.45% Medicare on all of it (plus 0.9% surtax over $200k), and 6.2% Social Security only on wages below the $184,500 cap, so high earners who've already maxed Social Security pay just Medicare. 3. State income tax, which in a place like California can add 9.3%+ on top.
How to close the withholding gap
You can ask payroll to withhold extra, make a quarterly estimated payment, or set aside the difference yourself. The cleanest mental model: figure your true combined marginal rate (federal + FICA + state) and reserve that much of every vest. To pressure-test your bracket, use the marginal tax rate calculator; for a same-style bonus, see the bonus tax calculator.
Questions
RSU Tax Calculator 2026 FAQ
How are RSUs taxed in 2026?
RSUs are taxed as ordinary income at their full market value when they vest. Your employer withholds federal tax at the 22% supplemental rate (37% above $1 million), plus FICA — 1.45% Medicare on everything and 6.2% Social Security up to the $184,500 wage base — and any state income tax. When you later sell the shares, any further gain or loss is a separate capital gain.
Why do I owe taxes on RSUs at filing?
Because the standard 22% supplemental withholding is often less than your real marginal rate. If your salary puts you in the 24%, 32% or 35% bracket, 22% under-withholds, and you owe the gap when you file. State tax can widen the shortfall further. Setting aside the difference or making an estimated payment avoids the surprise.
Do RSUs get hit with FICA tax?
Yes. At vesting, RSUs are wages, so Medicare (1.45%, plus the 0.9% surtax over $200,000) applies to the full value, and Social Security (6.2%) applies to the portion of your total wages below the $184,500 cap. If your salary already exceeds the cap, only Medicare is withheld on the RSUs.
Are RSUs taxed twice?
Not exactly. You're taxed once as ordinary income when they vest (on the full value), and again only on any additional gain when you later sell the shares. If you sell immediately at vest, there's little or no capital gain, so there's effectively one layer of tax. Holding and selling higher triggers a separate capital gains tax on the increase.
- Sources: IRS Publication 15 (Circular E) supplemental wage withholding · IRS Rev. Proc. 2025-32 (2026 brackets) · SSA 2026 wage base $184,500 · State departments of revenue.
- 🔄 Last updated June 27, 2026 · Tax year 2026
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