RSU withholding gap
One-sentence answer: Federal gap ≈ vest × max(0, your marginal − supplemental) / 100; state line uses the supplemental rate from our 50-state table.
This is the calculator people search for after a big vest. We keep the formula visible and load state rates from data on this site (as of 2026-07-13).
Table as-of: 2026-07-13. Change state to update the state line. Full table & sources
Formula
fed_gap = vest × max(0, marginal − supplemental) / 100
state_line = vest × state_supplemental / 100 (withholding-style illustration)
Example: $50,000 vest, 22% vs 32% → $5,000 federal gap before credits/deductions.
What to do next
- Sell-to-cover share count if you need cash for the gap.
- Quarterly sketch to spread remaining tax (not IRS safe-harbor).
- Moved this year? Residency allocation is a separate problem.
Educational only — not tax advice.
Common questions
- Why 22%?
- Many employers withhold federal income tax on supplemental wages (including RSU vests under the $1M threshold) at a flat rate set by IRS rules — commonly 22%. That is not your marginal ordinary rate.
- Is the state rate my final state tax?
- No. It is the supplemental withholding rate from our dated table for planning. Final liability is on your return.
- Does this include Social Security/Medicare?
- No. FICA is separate. This tool isolates income-tax withholding gap math.
- Is this tax advice?
- No. Educational arithmetic only.
- Where do state rates come from?
- The published table on this site with an as-of date — open the data page for sources.