Your employer withholds a flat 22% on RSU vests. See how much that could leave you owing when you file.
Enter your income, the number of shares, and a stock price greater than zero.
Estimated federal tax you would still owe at filing
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| RSU income this year | — |
|---|---|
| Extra federal income tax caused by your RSUs | — |
| Federal tax withheld on your RSUs | — |
| Shortfall | — |
| Effective tax rate on your RSU income | — |
| Your top federal bracket with RSUs | — |
| Potential underpayment penalty* | — |
| Quarterly estimated payment to close the gap | — |
Tax owed vs. tax withheld
This calculator is an illustration for general educational purposes and is not tax, legal, or investment advice. It uses 2026 federal income tax brackets and the standard deduction, treats your other income as wages already covered by normal paycheck withholding, and ignores state tax, Social Security and Medicare, the net investment income tax, AMT, credits, and other deductions. *The penalty is a rough estimate at 7% a year (the federal short-term rate plus 3% as of the fourth quarter of 2026, which the IRS resets each quarter), assuming your RSUs vest evenly through the year and the shortfall stays unpaid until the April filing deadline. You generally owe no penalty if your withholding and estimated payments cover at least 90% of this year's tax, or 100% of last year's tax (110% if last year's AGI was over $150,000).
When RSUs vest, the value of the shares is added to your income. Your employer usually withholds federal income tax by selling some of the shares and paying a flat 22%, no matter what your actual tax bracket is.
For many tech employees, 22% is too low. Your RSU income stacks on top of your salary, so it is taxed at your highest brackets, often 32%, 35%, or 37%. The difference between what was withheld and what you owe does not go away. It shows up as a bill when you file, and it can trigger an underpayment penalty on top.
The fix is to plan before the shortfall happens: make quarterly estimated payments, or ask your payroll team to withhold more from your regular paycheck.
This is a rough estimate. Book a free 15-minute call and we'll model your real vesting schedule.
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