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RSU Tax Calculator
RSU tax in one place — vest ordinary income + FICA + the 22% withholding shortfall, plus the capital-gains tax when you sell. Accurate, instant and free — for United States.
What these mean:
What these mean:
RSU vest: 1,000 shares at $50/share = $50,000 ordinary income. Employer withholds at 22% flat ($11,000), but your 35.0% marginal rate means you owe an extra $6,500 on your tax return.
Quarterly estimated-tax top-ups
Safe-harbor target = $69,196 (min of 90% of this-year tax) minus employer withholding of $11,000 = $58,196 top-up needed, split across 4 quarters.
| Quarter | Due date | Top-up (Form 1040-ES) |
|---|---|---|
| Q1 | Apr 15 | $14,549 |
| Q2 | Jun 16 | $14,549 |
| Q3 | Sep 15 | $14,549 |
| Q4 | Jan 15 (next yr) | $14,549 |
| Total | $58,196 | |
Underpayment of estimated tax may trigger a penalty (IRC §6654). If prior-year tax is $0, only the 90%-of-current-year test applies. Set prior-year tax above to unlock the 110% safe harbor.
Broker basis warning — avoid paying tax twice on your vest income
Your correct cost basis is $50,000 (1,000 shares x $50/share FMV at vest). On Form 8949 column (e), enter this amount with adjustment code B. Many brokers report a $0 cost basis on Form 1099-B because the shares were received rather than purchased — if you use $0, you pay capital-gains tax on the full sale proceeds, double-taxing income you already paid ordinary income tax on at vest.
How RSU tax is calculated — vest, then sale
RSUs create two taxable events. At vest, the share value is ordinary W-2 income — taxed, FICA-charged, and state-taxed, with your employer withholding federal tax at a flat 22% (37% over $1M). Because your real marginal rate is usually higher, that leaves a shortfall to set aside. At sale, you have a capital gain on the appreciation above the vest-FMV basis. Figures are TY 2026, cross-checked against IRS Pub 525/15-T and the SSA wage base.
Vest (ordinary income)
FMV × shares → shortfall
shortfall = fed marginal − 22% withheld
- Vest income = shares × FMV at vest (W-2)
- Withheld = 22% flat (37% over $1M cumulative)
- + FICA: SS 6.2% to $184,500, Medicare 1.45% + 0.9%
- + state tax on vest as wages
The shortfall is the headline "set aside" number.
Sale (capital gains)
basis = vest FMV → ST / LT + NIIT
gain = (sale price − vest FMV) × shares
- Basis = vest FMV (already taxed at vest)
- Held ≤ 1 yr → short-term, ordinary rate
- Held > 1 yr → long-term 0 / 15 / 20%
- + NIIT 3.8% over MAGI $200k / $250k
Holding period runs from vest date, not grant date.
- 1Vest — 1,000 RSUs at $50 FMV, ~35% marginal, CA resident, SS already maxed: Vest income is 1,000 × $50 = $50,000 ordinary income. Federal tax on it at the 35% marginal rate is about $17,500, but the employer withholds only 22% × $50,000 = $11,000 → a $6,500 shortfall to set aside.
- 2FICA and state on the vest income: With YTD wages already over the $184,500 Social Security wage base, only Medicare applies on the vest: 1.45% + 0.9% additional = $1,175. California supplemental withholding at 10.23% adds $5,115 in state tax on the vest (no-income-tax states like TX/FL/WA add $0).
- 3Sale — hold > 1 year, sell at $70: Gain = ($70 − $50) × 1,000 = $20,000 long-term × 15% = $3,000 capital-gains tax (plus NIIT 3.8% if your MAGI is over the threshold). Selling on the vest day instead would produce a roughly $0 gain.
US-only · figures are TY 2026
The safe-harbor rule — pay enough during the year to avoid a penalty
Because the 22% withholding under-withholds higher earners, the shortfall can trigger the IRS underpayment penalty (§6654 / Form 2210) for not paying enough during the year — not just at filing. The fix is to hit a safe-harbor target across four quarterly estimated-tax payments.
Safe-harbor target
The lesser of two tests
Pay the lesser of:
- • 90% of this year's total federal tax, or
- • 110% of last year's total federal tax
The 110% test applies because RSU recipients are almost always over the $150,000 AGI line. Withholding (including the 22% already taken) counts toward the target.
Four quarterly due dates
Form 1040-ES
- • Q1 — 15 April
- • Q2 — 15 June
- • Q3 — 15 September
- • Q4 — 15 January (next year)
The calculator splits the top-up needed beyond the 22% already withheld into these four payments, so you know exactly what to send by each date.
The $0-basis trap — don't pay tax twice on your vest income
This is the single most expensive RSU filing mistake. Brokers (E*TRADE, Fidelity, Schwab, and others) often report a $0 cost basis on Form 1099-B because the shares were received, not purchased. If you file that as-is, you pay capital-gains tax on the full sale proceeds — re-taxing income you already paid ordinary income tax on at vest.
- 1Find your correct basis: Your true cost basis is the FMV per share at vest × shares — the exact amount already reported as ordinary income on your W-2. The calculator surfaces this number for you to enter.
- 2Adjust on Form 8949: Enter the correct basis in column (e) and use adjustment code B to flag that the 1099-B basis was reported incorrectly. This caps your taxable gain to the post-vest appreciation only.
- 3Why it matters: On a $50,000 vest, a $0-basis error could double-tax the entire $50,000 — costing thousands. The correction is routine, but only if you catch it; the broker will not fix it for you.
Cross-links
Frequently asked questions
RSUs are taxed at two separate events. At vest, the fair market value of the shares (shares × FMV at vest) is ordinary W-2 income, subject to federal income tax, FICA (Social Security 6.2% up to the $184,500 wage base, plus Medicare 1.45% and an extra 0.9% over $200,000), and state tax. Your employer withholds federal tax on this at the flat supplemental rate of 22% (or 37% once cumulative supplemental wages exceed $1,000,000). At sale, you have a capital gain or loss on (sale price − vest FMV) × shares — short-term if held one year or less from vest (taxed as ordinary income), long-term if held more than a year (0/15/20% plus NIIT 3.8% where applicable). Your cost basis is the vest FMV, which was already taxed.
The 22% supplemental rate is flat, but most RSU recipients are at a 32–37% marginal rate, so too little is withheld and you owe the gap at filing. 1,000 RSUs vest at $50 = $50,000; at 35% the federal tax is about $17,500 but only 22% × $50,000 = $11,000 is withheld → $6,500 shortfall to set aside. To see how a separate cash bonus is withheld the same way, use the Bonus Tax Calculator.
Your basis is the FMV per share at vest — the amount already taxed as W-2 income. Gain at sale = (sale price − vest FMV) × shares. Brokers often report a $0 basis on Form 1099-B; using it double-taxes your vest income. Fix it on Form 8949 column (e), code B. For the capital-gains side in detail, see the Capital Gains Tax Calculator.
The holding period is measured from the vest date, not the grant date. If you sell more than one year after vest, the gain is long-term and taxed at 0/15/20% by income (plus NIIT 3.8% over MAGI of $200,000 single / $250,000 MFJ). If you sell within one year of vest, the gain is short-term and taxed as ordinary income at your marginal rate. Selling on the vest day itself produces a roughly $0 gain because the sale price equals the vest FMV basis — only later appreciation is a capital gain.
Possibly. Because 22% withholding under-withholds anyone at a 32–37% marginal rate, the shortfall is not just a filing-time surprise — it can trigger the IRS underpayment penalty (§6654 / Form 2210) for not paying enough during the year. The safe harbor is to pay the lesser of 90% of this year's tax or 110% of last year's tax (110% because RSU recipients are almost always over the $150,000 AGI line), spread across the four estimated-tax due dates: roughly 15 April, 15 June, 15 September, and 15 January. The calculator computes the per-quarter top-up needed beyond the 22% already withheld.
Method, assumptions & references
Methodology: vest income = shares × FMV at vest, taxed as ordinary W-2 income; federal marginal tax = tax on (other income + vest) − tax on other income; supplemental withholding = 22% flat (37% over $1M cumulative); shortfall = marginal − withheld. FICA: SS 6.2% up to the $184,500 wage base, Medicare 1.45% + 0.9% over $200k; plus state tax on the vest as wages. Sale: basis = vest FMV; gain = (sale price − vest FMV) × shares; ST ordinary / LT 0/15/20% + NIIT 3.8% over MAGI $200k/$250k. Golden example: 1,000 RSUs @ $50 → $50,000 vest, ≈$17,500 federal, $11,000 withheld, $6,500 shortfall, $1,175 Medicare, $5,115 CA state; sale LT $20,000 × 15% = $3,000. US-only, TY 2026; verify before acting. Not tax advice.
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed 21 June 2026. Figures follow the methods and sources set out in our editorial standards.
RSU tax rules here are US federal + state for TY 2026, cited from IRS Pub 525/15-T, Form 8949, §1411, and the SSA wage base. The withholding shortfall and quarterly estimated-tax figures depend on your marginal rate and prior-year tax. This is general information, not tax advice; consult a CPA or CFP for your situation.
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