RSU Calculator
Your vesting RSUs are withheld at a flat 22%, but your real tax depends on your bracket — this shows the shortfall you may owe at filing.
How it's calculated
At vest, the full value is ordinary income. Your employer withholds a flat 22%, but if your marginal bracket is higher, that under-withholds. The shortfall is the extra federal tax the vest actually creates minus what was withheld — the gap most free tools ignore.
Assumptions
- RSUs are taxed as ordinary income at vest and withheld at the flat 22% supplemental rate (37% on the portion above $1M). — IRS supplemental wage rules
- Actual tax is the extra federal income tax the vest adds at your marginal bracket. State and additional Medicare taxes are not included.
Last updated: 2026-08-07 · Tax year 2026
These assumptions follow our general methodology.
Frequently asked questions
Why do I owe tax on RSUs I did not sell?
RSUs are taxed as income when they vest, based on the share price that day, whether or not you sell. Selling later triggers separate capital-gains rules.
How do I cover the shortfall?
Options include selling extra shares at vest, increasing withholding elsewhere, or making an estimated tax payment. A tax professional can help.