Free Tool
RSU Tax Calculator
See the gap between the 22% federal withholding on your RSU vest and what the vest actually adds to your tax bill.
On a $150,000 salary with a $50,000 RSU vest in California, the standard 22% federal withholding covers about $11,000 of the $12,000 in federal tax the vest actually adds — leaving about $1,000 still owed, before FICA and state tax.
Estimated shortfall
beyond the federal and Additional Medicare amounts withheld at vest
Shares withheld (sell-to-cover)
75
Net shares delivered
125
Employers vary in how they round sell-to-cover shares; this estimates whole shares sold to cover federal withholding, FICA, and a state withholding stand-in based only on wages from this employer (actual state withholding is not modeled). Cost basis for a later sale is the $250.00 price at vest — a sale within one year of vest is a short-term capital gain or loss.
Estimated tax rate owed
39.0%
Estimated withholding rate
37.0%
Estimates use 2026 federal tables and the latest published state brackets (2026 where a state has released them, 2025 otherwise) and model one RSU vest taxed as supplemental wages, using single-filer state brackets with no state standard deduction or other state-specific adjustments. Not modeled: your employer's specific sell-to-cover rounding and timing, vest timing within the year (withholding depends on year-to-date wages), local or city taxes, tax credits, the Alternative Minimum Tax, and state income sourcing if you worked in a different state during the vesting period. State tax shown is always what the vest OWES at filing, not your employer's withholding. if a bonus or earlier vest from this employer already raised your wages this year, or if a spouse's wages or another job belong on the same return — each shifts a different part of the estimate above.
2026 federal tables from IRS Rev. Proc. 2025-32. Reviewed by Junead Khan. Last updated .
Why 22% withholding isn't the tax
When RSUs vest, the IRS treats the value as supplemental wages and lets employers withhold federal tax at a flat 22% (37% above $1,000,000 of year-to-date supplemental pay) — a simple, mechanical withholding rate, not a calculation of what you actually owe. What you owe is set by your ordinary federal tax brackets on your total income for the year, salary plus every vest.
For most people earning enough to land in the 24% bracket or higher once the vest is added, 22% withholding under-covers the vest and the difference comes due at filing. Social Security (6.2% up to the wage base), Medicare (1.45%, plus 0.9% above $200,000 from one employer), and most states' income tax are withheld separately and are not part of this federal gap.
RSU tax questions.
No, but it can look that way. RSUs are taxed once as ordinary (supplemental) income when they vest, based on the share price at vest. If you hold the shares afterward and their price changes, that later gain or loss is taxed separately as a capital gain or loss when you sell — a second, distinct event, not double taxation of the same dollars.
22% is the IRS flat rate for federal withholding on supplemental wages (which includes RSU vests) up to $1,000,000 of year-to-date supplemental pay — it is a withholding rate, not your tax rate. If your income (salary plus the vest) falls in a federal bracket above 22%, the vest adds more federal tax than was withheld, leaving a shortfall due at filing. If your total income stays in a bracket at or below 22%, the opposite can happen and you end up over-withheld.
At vest, not at grant. The value of the shares on the vesting date (shares × fair market value) is added to your W-2 wages as ordinary income that year, with federal, Social Security, Medicare, and (in most states) state income tax withheld at vest. Any gain or loss after that is a separate capital gain or loss, taxed only when you sell.
On a $150,000 salary with a $50,000 vest in California (single filer), this calculator estimates about $12,000 in additional federal tax and about $4,650 in additional California state tax from the vest, plus $2,864 in Social Security and Medicare. Enter your own numbers above for your figures.
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