My employer withheld 22% — am I done?

Twenty-two percent is a common federal supplemental withholding rate under Publication 15, not a promise that 22% is your total tax. High earners often owe more at filing when the vest pushes income into higher brackets.

Does sell-to-cover mean there is no gap?

Sell-to-cover funds withholding; it does not change your tax rate. If withholding rates are lower than your actual marginal tax, you can still owe after shares are sold for taxes.

Can I fix this for the next vest?

Many people increase W-4 withholding on salary, request extra withholding on the next vest if the plan allows, or make quarterly estimated payments. Which option fits depends on how many vests remain in the year.

Why does the calculator ask for my marginal rate?

Flat withholding is not tied to your bracket. Entering a marginal rate lets the tool compare a rough tax on the vest slice to what was withheld. Leave it blank if you only want to see withholding totals.

RSU tax calculator

RSU Withholding Gap Calculator

Focus on the gap between what your employer withholds on RSU vests and what you may owe when everything is reconciled.

Your RSU vest already happened (or is about to) and the withholding rate looks too low for your income. This page is for employees who want to see the dollar gap between employer withholding and a rough full tax estimate before April.

Gather before you start

confirmation showing gross value and amounts withheld.
Federal and state rates your employer used (from the notice or pay stub).
Your expected marginal federal rate for the year, from last year's return or a bracket table.
State of residence on the .
Other large income this year (bonus, second , spouse wages if filing jointly).

Compares simplified estimates to typical withholding. Your employer's actual rates and your full return can differ.

In plain terms

Enter details, salary, and your if you know it. The calculator compares estimated federal, state, and payroll tax on the to typical supplemental so you can see how much extra to set aside.

Planning estimate

Rough estimate for planning, not a filing number. Check your pay stubs, W-2, and a tax pro before you rely on it.

We do not pre-fill personal financial values. Estimates appear only after you enter your own numbers.

Enter your details to estimate

Add your equity, income, state, and withholding details to see an educational estimate. No personal financial values are pre-filled.

Start with the fields below.

Your details

Enter your own numbers below. This is an estimate, not a filing position.

Tax year

Calculators pull rates from our tax-year files. For the most complete defaults, use 2025. Unloaded years ask you to enter rates yourself.

Filing status

Used for federal tax brackets and Medicare thresholds.

State

State tax uses a simplified flat effective rate when loaded. See calculator methodology for how state estimates work.

Annual base salary (optional)

Expected W-2 salary for the year, before RSU vests. Improves the marginal-rate estimate.

Annual bonus / other W-2 income (optional)

Other ordinary wages expected this year.

RSU vest value

Total fair market value of RSUs vesting, ordinary income at vest.

Required to estimate

Federal supplemental withholding rate

Employers often use the IRS supplemental rate for RSU vests under $1M. Adjust if yours differs.

State withholding rate

Default estimate for your state (2025): 10.2%. Edit if your employer uses a different rate.

Social Security wages already earned this year (optional)

Wages subject to Social Security so far. RSU vests count toward the wage base. Leave blank if unsure.

Include Medicare taxes (1.5%)Include Additional Medicare Tax estimate (0.9% above threshold)

Marginal tax rate override (optional)

Used when federal bracket estimate is unavailable. When loaded, brackets take precedence.

Results will appear here once you enter the required details on the left.

Related guides

When to use this calculator

Your confirmation or pay stub shows flat supplemental (often 22% federal on the income-tax portion) but you suspect your real bracket is higher.
Salary, bonus, and vests stack in one year and you want to see whether payroll may fall short of estimated tax.
You are planning estimated tax payments or W-4 changes after a surprise balance due last filing season.

Inputs you need

value (or total income expected this year).
Annual salary and bonus.
Filing status, state, tax year, and the supplemental rate shown on your or pay stub if different from defaults.

How to interpret the result

The gap is the difference between estimated tax on combined wages and what flat supplemental typically covers on the portion.
A positive gap is a planning signal — not a bill. Many people cover it with extra W-4 on salary, estimated payments, or proceeds set aside.
Payroll taxes (Social Security and Medicare) are separate from the federal income-tax gap; check both on your pay stub.

What this calculator does not know

Employer-specific supplemental tax plans, gross-up policies, or custom elections.
Whether your state uses the same flat supplemental method as federal payroll.
Credits, deductions, or capital losses that change your final liability.
Quarterly estimated payment safe-harbor rules for your situation — see IRS estimated tax guidance for details.

Documents to verify before filing

or payroll notice showing rate and amounts.
Pay stubs for the pay period and a normal salary period (compare wage jumps).
Prior-year return if you owed a balance after vests.
W-4 on file with your employer if you changed exemptions recently.

Next pages to read

These links are for education and planning. They are not filing instructions and do not replace review of your own documents or a qualified tax professional.

How the tax works

uses simplified rates. IRS Publication 15 describes optional flat rates employers may use on bonuses and many equity vests.

Your actual tax on the depends on where that income falls in your total-year wages, not the flat rate on the line alone.

Payroll tax and state are calculated separately and may not match your full-year liability either.

What to check on your end

Flat supplemental rate on the vs. your marginal federal rate.
Whether state matches your expected state liability.
Social Security wage base: if you already hit the cap, FICA on the may differ from what you expect.
Total gap in dollars, not just percentage points.
Whether you should adjust W-4 or make estimated payments for the remaining year.

Assuming a small gap does not matter

A few thousand dollars of under- on one can repeat on every quarterly . Engineers with refresh grants sometimes discover the gap only after three or four vests stack in the same year.

What to pull from your files

confirmation: federal, state, and FICA withheld on the line.
Pay stub after : line vs. regular salary .
W-4 on file with employer (does not always update automatically after a raise).
Prior-year return: did income create a balance due last year too?

Example scenario (hypothetical)

Illustration only, not your tax situation.

Example: Priya vests $40,000. The employer withholds 22% federal plus state at a flat rate. Priya's marginal combined rate is closer to 38% when federal, state, and payroll taxes are counted. The calculator shows an gap of several thousand dollars to cover before filing, even though the notice looked "normal."

Questions people ask

My employer withheld 22% — am I done?: Twenty-two percent is a common federal supplemental rate under Publication 15, not a promise that 22% is your total tax. High earners often owe more at filing when the pushes income into higher brackets.
Does sell-to-cover mean there is no gap?: funds ; it does not change your tax rate. If rates are lower than your actual marginal tax, you can still owe after shares are sold for taxes.
Can I fix this for the next vest?: Many people increase W-4 on salary, request extra on the next if the plan allows, or make quarterly estimated payments. Which option fits depends on how many vests remain in the year.
Why does the calculator ask for my marginal rate?: Flat is not tied to your bracket. Entering a lets the tool compare a rough tax on the slice to what was withheld. Leave it blank if you only want to see totals.

When a CPA is worth it

The gap is large and you also exercised stock options this year.
You are subject to additional Medicare tax or NIIT and unsure how interacted.
You want a plan for estimated payments vs. W-4 changes.
You moved states mid-year and looks wrong on the .

Sources and notes

Primary tax claims on this page are supported by the official and secondary sources below. Broker and software links describe reporting mechanics — confirm rules against IRS or state guidance.

Flat supplemental withholding vs estimated full-year tax liability.

IRS Publication 15 (Circular E) — Supplemental wages
Internal Revenue Service · Official
Section 7 describes supplemental wage withholding, including the optional 22% flat rate and 37% rate above $1 million of supplemental wages in a calendar year.
IRS Tax Withholding Estimator
Internal Revenue Service · Official
Tool to estimate whether paycheck withholding (including supplemental events) will cover annual tax liability.

Related calculators

For learning, not filing

VestingTax.com is not a CPA firm or tax preparer. Grants, employers, and states all differ. Use the cited IRS and state sources above, your own documents, and a qualified tax professional before you make decisions from this guide.

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