Gross up calculator
Enter the net amount the employee should keep. This solves the gross payment that delivers it, and it asks for year-to-date wages because the Social Security cap and the extra Medicare rate move the answer.
The one-line formula and the solve agree here, both landing on $7,645, because $7,645 of pay sits below the $184,500 Social Security wage base. Raise the year-to-date box above that base and the two answers part company.
Where the one-line formula breaks
The gross-up tools I checked on the first page of results divide once, by one minus the sum of three rates. Here is the same target net run three ways, at a year-to-date figure above the wage base.
The shared shortcut is net / (1 - 22% - 7.65% - state rate). It is right while all three rates apply to every dollar of the payment, and two of them do not. Social Security stops once wages reach $184,500 in the year, so an employee already past that base has 6.2% taken out of the divisor and the shortcut asks for more gross than the job needs. The additional Medicare rate of 0.9% starts once wages pass $200,000, so a large payment crosses into a deeper divisor partway through and a shortcut that only remembers the wage base comes up short.
The run below targets a net of $40,000 in Illinois for an employee already paid $195,000 this year, which is $10,500 past the wage base and an ordinary place for a relocation or retention payment to land.
| Method | Gross it asks for | Net it delivers | Gap |
|---|---|---|---|
| One line divide, all three rates held constant | $61,162 | $43,287 | +$4,649 |
| One line divide with Social Security dropped | $55,866 | $39,542 | -$647 |
| Solved by bisection on the real withholding | $56,513 | $40,000 | reference |
The second row is the other direction, and it is the error a payroll team is more likely to make. Drop Social Security from the divisor because the employee is past the base, keep everything else, and you get $55,866. That is $647 light, because $51,513 of this payment sits above the $200,000 withholding threshold and carries the extra 0.9%. The employee banks $39,542, which is $458 short of the $40,000 that was promised.
Neither error is large as a percentage. Both are large as a cheque. One division cannot be right on both sides of a breakpoint, which is why this page bisects instead.
The withholding behind the solved gross
The default run above, line by line, so the arithmetic closes in front of you. Figures are rounded to the dollar.
Illinois publishes a flat supplemental withholding rate of 4.95%, read from that state's own withholding instructions.
Nothing here reaches the $200,000 additional Medicare threshold, so the extra 0.9% does not apply and filing status moves nothing on this payment.
Read that card as an employer and the cost is the interesting line. A promise of $5,000 net costs $7,645 gross in Illinois, so $2,645 of the payment never reaches the person it was promised to. That is 34.6% of the cheque going to withholding before anyone is any better off.
The solve is a bisection. Net rises monotonically with gross, because every marginal withholding rate here sits well below one hundred percent, so an interval that brackets the answer can be halved until the net lands within 0.001 of a dollar of the target. The loop carries a fixed iteration cap, the same hardening the reverse paycheck solver in this site's tax engine uses. The gross is then rounded to a whole dollar, which is why the delivered net sits within about a dollar of the figure you asked for rather than on it.
What the same net costs in each state
The gross needed to deliver $5,000 net, at zero year-to-date wages, in every state that publishes a flat supplemental withholding rate. Each state name links to the document the rate was read from.
| State | Supplemental rate | Gross needed | Versus a no-tax state |
|---|---|---|---|
| North Dakota | 1.5% | $7,262 | +$155 |
| Pennsylvania | 3.07% | $7,432 | +$325 |
| Nebraska | 3.5% | $7,479 | +$372 |
| Arkansas | 3.7% | $7,502 | +$395 |
| Iowa | 3.8% | $7,513 | +$406 |
| North Carolina | 4.09% | $7,546 | +$439 |
| Oklahoma | 4.5% | $7,593 | +$486 |
| Illinois | 4.95% | $7,645 | +$538 |
| Georgia | 4.99% | $7,650 | +$543 |
| Alabama | 5% | $7,651 | +$544 |
| Maine | 5% | $7,651 | +$544 |
| Montana | 5% | $7,651 | +$544 |
| Idaho | 5.3% | $7,686 | +$579 |
| Virginia | 5.75% | $7,740 | +$633 |
| New Mexico | 5.9% | $7,758 | +$651 |
| Minnesota | 6.25% | $7,800 | +$693 |
| California | 6.6% | $7,843 | +$736 |
| Oregon | 8% | $8,019 | +$912 |
| New York | 11.7% | $8,525 | +$1,418 |
The floor is $7,107, which is what the same promise costs in the 9 states that levy no income tax on wages, being Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming. The ceiling is New York at $8,525. Moving the same employee across that spread changes the cost of one $5,000 promise by $1,418, which is why a gross-up budget built on a single national rate misses.
19 of the 51 jurisdictions publish a flat supplemental rate this page can stand behind for 2026, and 9 levy no income tax on wages at all. The remaining 23 either send the employer back to the regular withholding tables or published no rule this run could confirm. Pick one of those and the calculator falls back to a general effective-rate estimate and says so under the breakdown.
Common questions
How does a gross up calculator work
A gross up calculator starts from the net amount an employee must keep and works backwards to the gross payment, by taking the withholding that will be taken out of that gross and searching for the gross whose net matches the promise.
The common shortcut divides the net by one minus the sum of the withholding rates. That is a fair approximation while every rate applies to every dollar. It stops being one at the Social Security wage base and at the additional Medicare threshold, which is why this page searches for the answer instead of dividing once.
Why does year-to-date pay change the gross up
Because two of the three federal rates depend on how much the employee has already been paid this year. Social Security stops at $184,500 of wages, so someone past that base needs a smaller gross. The additional Medicare rate of 0.9% starts at $200,000 of wages and needs a larger one. A calculator that never asks for year-to-date pay is quietly assuming the answer is zero.
Does filing status change a gross up
Not the withholding. Under the flat method the federal rate is 22% whatever the W-4 says, and the additional Medicare rate is withheld above $200,000 of wages without regard to filing status. Filing status changes what is finally owed. In the run above the employer withholds $463.62, but a married employee filing jointly owes it only above $250,000 measured on the couple's combined Medicare wages, not on this employee's alone. On the wages modelled here, and only on those, $13.62 is the real liability and $450 would come back at filing. A working spouse moves that figure, and can remove it.
Is a grossed up payment tax free for the employee
No. It is withheld against, not exempt. The gross up covers the withholding so the agreed net arrives on payday, and the whole gross is still reported as wages. The bill is settled on the annual return at the employee's own marginal rate, which can sit above or below 22%, so a high earner can still owe more in April.
What happens above one million dollars of supplemental wages
The federal rate steps up. IRS Publication 15 states that the withholding rate on supplemental wages remains 22%, 37% if supplemental wages paid to an employee during the calendar year exceed $1,000,000. This page applies the higher rate to the slice of the payment that carries the year-to-date figure past that million. It treats that box as wages already paid for the test, so if the figure is regular salary rather than supplemental pay the higher band switches on earlier than payroll will.
What this leaves out
The result is an estimate, not tax advice. It models withholding on a supplemental payment made separately from regular wages, under the flat federal method. It excludes pre-tax deductions such as a 401(k) or an HSA, local and city income taxes, state disability and family leave contributions, wage garnishments, tax credits, and anything specific to your employer's payroll setup. It does not model the aggregate method, where the payment is added to concurrently paid regular wages and withheld as a single payroll period.
State supplemental rates come from the 2026 dataset above. Where a state publishes no flat rate, the page substitutes an effective-rate estimate and labels it, so treat that line as an approximation. Federal withholding, Social Security and Medicare are modelled directly from the published rates and thresholds.
Sources and method
The federal side of this page comes from two IRS documents and nothing else. The flat supplemental method, the 22% rate and the $1,000,000 step to 37% are from IRS Publication 15, Circular E, Employer's Tax Guide, section 7, which states "Withhold a flat 22% (no other percentage allowed)" and describes the alternative aggregate method as adding the supplemental wages to concurrently paid regular wages and withholding "as if the total were a single payment for a regular payroll period". The Social Security rate and wage base and the Medicare rates are from IRS Tax Topic 751, Social Security and Medicare Withholding Rates.
Per-state supplemental rates are read row by row from this site's 2026 state dataset, and every verified row carries the state document it came from. Those documents are linked from the state names above, so each figure points at its own source. Rates and thresholds are held in the site's tax engine, verified August 2026.
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Every figure here is an estimate for the 2026 tax year, not tax advice. It excludes pre-tax deductions, local taxes and credits, and models withholding rather than final liability. Confirm any payment with your payroll provider or a tax professional first.