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.
Want to understand the concept, not just the number? Read The RSU Tax Guide and more below.
How it's calculated
When RSUs vest, the full value counts as ordinary income that day, based on the share price. Your employer withholds tax at the flat 22% supplemental rate, the same default used for bonuses.
The problem is that many people who receive RSUs are in a higher bracket than 22%. Take someone with $150,000 of base income and a $50,000 vest. The flat rate withholds $11,000, but the vest actually falls in the 24% bracket and creates $12,000 of federal tax. That is a $1,000 shortfall you have to cover at filing, and most free RSU tools never show it.
The larger your vest and the higher your bracket, the bigger the gap. Knowing it ahead of time lets you set money aside or adjust your withholding, instead of being surprised by a bill in April.
Assumptions
- RSUs are taxed as ordinary income at vest and withheld at the flat 22% supplemental rate, or 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.
Do I get taxed again when I sell?
Only on the gain since vesting. The vest value was already taxed as income, so if the shares rise before you sell, that increase is taxed as a capital gain. If they fall, you may have a loss.