Calculator · tax year 2026
RSU vest: will the flat withholding fall short?
Enter your other income and the value of the vest. The calculator works out the federal income tax the vest adds and compares it with the flat withholding.
Tax year 2026 Checked Review by
CheckedOct 19, 2026
When restricted stock units vest, the value of the shares is wages. Your employer usually withholds federal income tax on that value at the flat supplemental rate of 22%. That rate is a withholding convention, not your tax rate.
Your actual tax on the vest depends on where the vest lands in your brackets. If the vest sits in a bracket above the flat rate, the difference shows up when you file. This calculator estimates that difference, so you can see how the rule plays out with your own numbers.
The calculator
This calculator runs in your browser with JavaScript. Without it, the steps under How the estimate works give the same result by hand, with the same figures.
Your entries stay on this device. Nothing you type is sent anywhere.
Your estimate
Enter your numbers and choose Estimate.
Estimates for education only, from the federal figures listed below. This is general information as of the date shown, not advice for your situation. The right answer depends on your facts, so check how it applies to your own situation before you act on it.
How the estimate works
The calculator follows these steps, in this order.
- Start with your other income for the year and subtract your deductions. That is taxable income without the vest.
- Deductions: the standard deduction for your filing status (for example $16,100 single, $32,200 joint), plus $2,050 (single or head of household) or $1,650 (married) for each person who is 65 or older or blind. If you itemize, your itemized total replaces all of that.
- If anyone on the return is 65 or older, add the senior deduction of $6,000 per person, each reduced by 6% of income over $75,000 ($150,000 on a joint return). Married people filing separately cannot take it.
- Work out the tax on that taxable income from the rate schedule for your filing status. The rates are 10%, 12%, 22%, 24%, 32%, 35% and 37%; where each bracket starts depends on filing status, and the full schedules are under Figures used.
- Add the vest to your other income and do the same again: deductions, taxable income, tax.
- The extra tax from the vest is the second tax minus the first.
- Withholding on the vest is the flat rate of 22% times the vest (and 37% on any part above the Publication 15 threshold), unless you enter the amount actually withheld.
- Extra tax minus withholding is the estimated shortfall. A negative result is a cushion: the withholding covers more than the vest adds.
Worked example
Hypothetical example, not law and not a client
Sam files single, earns 180,000 dollars of salary this year and has RSUs worth 60,000 dollars vest. Sam takes the standard deduction of $16,100.
- Without the vest: 180,000 minus $16,100 is 163,900 dollars of taxable income. Tax: $17,966 on the first $105,700, plus 24% of the 58,200 above it (13,968), so 31,934 dollars.
- With the vest: 223,900 dollars of taxable income. Tax: $41,024 on the first $201,775, plus 32% of the 22,125 above it (7,080), so 48,104 dollars.
- Extra tax from the vest: 48,104 minus 31,934 is 16,170 dollars, about 27 cents of each vest dollar.
- Withholding at 22%: 13,200 dollars.
- Estimated shortfall: 16,170 minus 13,200 is 2,970 dollars, due when Sam files unless other withholding or payments cover it.
What this does not cover
- State and local income tax. Most states withhold on a vest too, at their own rates.
- Social Security and Medicare on the vest. Those are withheld separately at 6.2% (up to the wage base of $184,500) and 1.45%, plus the Additional Medicare Tax on high wages.
- Whether the withholding on your regular paychecks is itself too high or too low. This looks at the vest alone.
- Capital gains when you later sell the shares, the net investment income tax, the alternative minimum tax and tax credits.
- Qualified dividends and long-term capital gains, which are taxed on top of ordinary income at their own rates. All income here is treated as ordinary.
- Penalties for paying too little during the year, and the safe harbors that avoid them.
- The IRS tax table, which rounds lower incomes into bands. Your return can differ from this estimate by a few dollars.
Read more
The tax code
Questions
Why is my RSU vest withheld at a flat rate?
The vest is supplemental wages. When an employer pays supplemental wages separately from regular pay, IRS Publication 15 lets it withhold federal income tax at a flat 22%, and requires 37% on supplemental wages above an annual threshold.
Does the flat withholding rate equal the tax I owe on the vest?
Not necessarily. The tax on the vest depends on the brackets it lands in on your return. If the vest falls in a bracket above the flat rate, the withholding can fall short; if it falls in a lower bracket, the withholding can be more than the tax.
What does a shortfall mean?
It is the part of the tax the vest adds that the withholding on the vest did not cover. It is paid with the return unless other withholding or estimated payments during the year cover it.
Is this advice about my situation?
No. It is an estimate for education that shows how the rule works with the figures for the tax year. Your return depends on facts this page does not ask about, so check how it applies to your own situation before you act on it.
Figures used
Tax year 2026. Every figure the calculator reads comes from the verified library behind this site, with its source, the date it was checked and the date it is due for a re-check. If any figure passes its review date, the calculator pauses until it is re-checked.
| Figure | Value | Source | Checked | Review by |
|---|---|---|---|---|
Flat withholding rate on supplemental wagesfederal-2026:withholding.supplemental_wages_flat_rate_pct | 22% | Pub. 15 (2026) What's New | CheckedSep 24, 2026 | |
Mandatory withholding rate on supplemental wages above the annual thresholdfederal-2026:withholding.supplemental_wages_rate_over_1_million_pct | 37% | Pub. 15 supplemental wages rule | CheckedSep 24, 2026 | |
Tax rate schedule: singlefederal-2026:income_tax.rate_schedules.single | 10% up to $12,400; 12% up to $50,400; 22% up to $105,700; 24% up to $201,775; 32% up to $256,225; 35% up to $640,600; 37% above $640,600 | Rev. Proc. 2025-32 sec. 4.01 | CheckedSep 24, 2026 | |
Tax rate schedule: married filing jointly or qualifying surviving spousefederal-2026:income_tax.rate_schedules.married_filing_jointly_and_surviving_spouse | 10% up to $24,800; 12% up to $100,800; 22% up to $211,400; 24% up to $403,550; 32% up to $512,450; 35% up to $768,700; 37% above $768,700 | Rev. Proc. 2025-32 sec. 4.01 | CheckedSep 24, 2026 | |
Tax rate schedule: married filing separatelyfederal-2026:income_tax.rate_schedules.married_filing_separately | 10% up to $12,400; 12% up to $50,400; 22% up to $105,700; 24% up to $201,775; 32% up to $256,225; 35% up to $384,350; 37% above $384,350 | Rev. Proc. 2025-32 sec. 4.01 | CheckedSep 24, 2026 | |
Tax rate schedule: head of householdfederal-2026:income_tax.rate_schedules.head_of_household | 10% up to $17,700; 12% up to $67,450; 22% up to $105,700; 24% up to $201,750; 32% up to $256,200; 35% up to $640,600; 37% above $640,600 | Rev. Proc. 2025-32 sec. 4.01 | CheckedSep 24, 2026 | |
Standard deduction: singlefederal-2026:standard_deduction.basic.single | $16,100 | Rev. Proc. 2025-32 sec. 4.14 | CheckedSep 24, 2026 | |
Standard deduction: married filing jointly or qualifying surviving spousefederal-2026:standard_deduction.basic.married_filing_jointly_and_surviving_spouse | $32,200 | Rev. Proc. 2025-32 sec. 4.14 | CheckedSep 24, 2026 | |
Standard deduction: married filing separatelyfederal-2026:standard_deduction.basic.married_filing_separately | $16,100 | Rev. Proc. 2025-32 sec. 4.14 | CheckedSep 24, 2026 | |
Standard deduction: head of householdfederal-2026:standard_deduction.basic.head_of_household | $24,150 | Rev. Proc. 2025-32 sec. 4.14 | CheckedSep 24, 2026 | |
Extra standard deduction per box (65 or older, or blind): married or surviving spousefederal-2026:standard_deduction.additional_aged_or_blind_per_condition.married_or_surviving_spouse | $1,650 | Rev. Proc. 2025-32 sec. 4.14 | CheckedSep 24, 2026 | |
Extra standard deduction per box (65 or older, or blind): single or head of householdfederal-2026:standard_deduction.additional_aged_or_blind_per_condition.unmarried_not_surviving_spouse | $2,050 | Rev. Proc. 2025-32 sec. 4.14 | CheckedSep 24, 2026 | |
Senior deduction per person 65 or olderfederal-2026:obbba_deductions.senior_deduction.amount_per_qualified_individual | $6,000 | 26 U.S.C. sec. 151(d)(5)(C) | CheckedSep 24, 2026 | |
Senior deduction phase-outfederal-2026:obbba_deductions.senior_deduction.phaseout | 6% of modified AGI over $75,000 ($150,000 on a joint return) | 26 U.S.C. sec. 151(d)(5)(C)(iii) | CheckedSep 24, 2026 | |
Income tax: ordinary ratesfederal-2026:income_tax.ordinary_rates | as quoted above | Rev. Proc. 2025-32 sec. 4.01 | CheckedSep 24, 2026 | |
Payroll and SE tax: medicare rate, employee and employer eachfederal-2026:payroll_and_se_tax.medicare_rate_pct.employee_and_employer_each | 1.45% | SSA contribution and benefit base page | CheckedOct 11, 2026 | |
Payroll and SE tax: social security rate, employee and employer eachfederal-2026:payroll_and_se_tax.social_security_rate_pct.employee_and_employer_each | 6.2% | SSA contribution and benefit base page | CheckedOct 11, 2026 | |
Payroll and SE tax: social security wage basefederal-2026:payroll_and_se_tax.social_security_wage_base | $184,500 | SSA contribution and benefit base table | CheckedOct 11, 2026 |