How the RSU tax calculator works

2026 tax year · Checked Oct 25, 2026

One vest’s withholding, the way payroll runs it, against the tax the vest adds to your year: your tax with the vest less your tax without it. Then, if you sell, the capital gains tax on the shares you kept.

Open the RSU tax calculator

Step by step

1. What payroll withholds

Federal at the flat supplemental rate, 22% (37% on supplemental pay above $1,000,000 in the year, counting your bonuses and other vests at their value before tax). State at its supplemental rate, a flat-tax state’s rate, or your marginal state rate. Social Security on whatever is left under the $184,500 wage base after your salary and other vests, Medicare at 1.45%, and 0.9% more above $200,000. State payroll programs come out too: California SDI (1.3%, no cap), WA Cares (0.58%) and Washington Paid Leave (0.81% up to the wage base), New York Paid Family Leave (0.432%, up to $411.91 a year) and New Jersey disability and family leave (0.42% up to $171,100).

2. What the vest adds

Federal and state income tax on your salary, other vests and this vest, less pre-tax 401(k) and the standard deduction, minus the same without this vest. Social Security and Medicare owed match what’s withheld at one employer, except Additional Medicare, which is owed above $200,000 single or $250,000 joint. Federal and state are separate returns, so what’s still to pay never nets a state refund against a federal bill.

3. Shares sold

Whole shares are sold at the vest price to cover the withholding; the leftover cash comes back to you. Each kept share’s cost basis is the vest price, since that value was already taxed as pay.

4. When you sell

The gain is the sale price less the vest price on the shares you kept. Held more than a year from the vest date (from the day after the anniversary), it is long-term: 0%, 15% or 20% federal, stacked on top of your other taxable income. Sooner, it is taxed as ordinary income. The 3.8% Net Investment Income Tax applies to the part of the gain above $200,000 of income single ($250,000 joint). States tax gains as income; Washington instead taxes long-term gains at 7% above $278,000 a year and 9.9% on taxable gains over $1M. A loss deducts up to $3,000 a year from other income and carries the rest forward. The year you sell is assumed to have the same pay as this one.

Figures used

Federal withholding on vests: 22% (37% over $1,000,000)
Social Security wage base: $184,500
California / New York supplemental rate: 10.23% / 11.7%
Long-term capital gains, single: 0% to $49,450, 15% to $545,500, then 20%
Washington capital gains deduction: $278,000 (2025; 2026 not yet published)

Assumed

One employer, and no other income, deductions or credits.
Your salary is for the whole year.

Not modeled

Moving states between grant and vest.
Estimated payments or extra withholding you already make.
New York City and Yonkers income tax, and New York’s tax benefit recapture at high incomes.
Payroll programs in states other than California, Washington, New York and New Jersey.
Partial state exclusions for capital gains, and other gains or losses you have the same year.
Wash sales beyond a note when a sale is at a loss.

Sources

These are estimates for education, not tax or investment advice. If a number looks wrong, report a problem with this calculation and say what you entered.