How to Use the RSU Stock Grant Tax Calculator
When RSUs vest, they count as ordinary supplemental wage income subject to federal withholding, not a capital gain. Rather than receiving every share you were granted, most employers use a "sell-to-cover" method โ automatically selling enough of your newly vested shares to cover the withholding, so only what's left actually lands in your brokerage account.
This calculator applies the IRS's flat federal supplemental wage withholding rate: 22% on RSU income up to $1,000,000 in cumulative supplemental wages for the year, and 37% on any amount above that. It also applies FICA tax โ 6.2% Social Security tax up to the annual wage base ($176,100 for 2025) and 1.45% Medicare tax with no cap, plus an additional 0.9% Medicare surtax on wages above $200,000. Your year-to-date wages before this vest determine how much of each threshold you've already used.
Adding up federal withholding and FICA tax gives the total withholding, which is then converted into a number of shares sold to cover by dividing by the share price. The remaining shares and their value are shown as your net payout. Keep in mind this calculator only covers federal withholding at vesting โ state income tax and any capital gains tax from selling the remaining shares later at a different price are not included.
Frequently Asked Questions
Vested RSUs count as ordinary (supplemental) wage income subject to federal withholding and FICA tax. Most employers use a "sell-to-cover" method, automatically selling enough shares to pay the withholding, so only the remaining shares actually land in your account.
The IRS requires a flat 22% federal supplemental wage withholding rate on RSU income up to $1 million in cumulative supplemental wages for the year, and 37% on the amount above that. Social Security tax (6.2%) applies only up to the annual wage base, and Medicare tax (1.45%, plus 0.9% on wages over $200,000) has no cap.
No. This calculator only covers the withholding taken at vesting. If you hold the remaining shares and sell them later at a higher price, that additional gain is taxed separately as a capital gain.