Retro Pay Calculator
Work out the retroactive back pay you are owed when a raise starts late, for hourly or salaried workers, then see the after-tax amount.
Retro Pay Calculator
Pay type
Total hours across every affected pay period.
A lump sum retro figure, such as a promised amount that was skipped.
Filing status
Filing status only affects the Additional Medicare threshold note. The 22% supplemental federal rate is the same for every status.
Year-to-date wages (optional)
Supplemental YTD drives the $1M crossover to 37%. Social Security YTD truncates the 6.2% once you reach the $184,500 wage base.
Medicare here is the base 1.45%. The Additional Medicare 0.9% only kicks in once your YTD wages pass $200,000.
Estimate only. State income tax also applies in most states, and your employer may use the aggregate method or a different W-4 result, so your actual paycheck can vary.
How to calculate retro pay (hourly vs salary)
Retro pay always starts as a gross figure: the gap between what you should have been paid and what you actually got, across the affected pay periods. The math splits by how you are paid.
Hourly: subtract the old rate from the new rate and multiply by the hours paid at the old rate. A raise from $20 to $22 across 160 hours works out to ($22 − $20) × 160 = $3,200 gross.
Salary: divide the old and new annual salary by paychecks per year, take the per-period difference, and multiply by the number of affected periods. Going from $52,000 to $56,000 on biweekly pay (26 checks) is a per-check shortfall of $153.85, so three late periods owe about $461.54 gross.
Retro pay and taxes: why your check is smaller than the gross
The IRS classifies retro pay as supplemental wages, so it is not taxed at your normal bracket. Employers usually withhold federal income tax by the flat 22% percentage method, which rises to 37% on any supplemental wages above $1,000,000 for the year. The alternative aggregate method lumps the retro into a regular paycheck and withholds by your W-4, which can land higher or lower.
FICA applies like any other wages: 6.2% Social Security up to the $184,500 wage base for 2026, plus 1.45% Medicare with no cap. State income tax usually applies on top, and many states have their own supplemental rate, so treat the net figure here as a federal-only estimate. The same supplemental treatment drives the bonus tax calculator and the severance pay calculator.
Common reasons employees are owed retro pay
- A raise with an effective date earlier than the paycheck it first appeared on.
- Missed shift differentials for nights, weekends, or hazard work.
- Miscalculated overtime, where hours were paid at the old rate. The overtime pay calculator finds the corrected overtime rate first.
- Union or contract settlements that backdate a new wage scale.
- Plain payroll errors, such as a rate that was keyed in wrong for a few periods.
For the full take-home on the corrected pay going forward, the hourly paycheck calculator and salary to paycheck calculator cover the ongoing paycheck, while the prorated salary calculator handles partial-period pay.
From estimate to exact: running retro pay in Payroll Calculator
This page handles one worker and federal math. When you need the exact number across a team, the Payroll Calculator app layers full federal, state, and FICA per employee, tracks year-to-date wage bases, and rolls a retro line into a real payroll run for all 50 states plus DC, with decimal-precise math instead of a rounded estimate.
Frequently Asked Questions
Common questions about retro pay calculator
What is retroactive pay?
Retroactive pay is compensation for work already performed but underpaid at the time. The most common case is a raise that took effect before it first showed up on a paycheck, but it also covers missed shift differentials, miscalculated overtime, or a late union or contract settlement.
How do I calculate retro pay for an hourly employee?
Subtract the old hourly rate from the new hourly rate and multiply by the hours that were paid at the old rate. For example, a raise from $20 to $22 over 160 hours is ($22 − $20) × 160 = $3,200 gross retro pay. For the take-home on the corrected rate going forward, see the hourly paycheck calculator.
How do I calculate retro pay for a salaried employee?
Divide both the old and new annual salary by paychecks per year, take the per-period difference, and multiply by the number of affected pay periods. If a $52,000 salary rises to $56,000 on biweekly pay (26 checks), the per-check shortfall is ($56,000 − $52,000) / 26 = $153.85, so three affected periods owe about $461.54. The prorated salary calculator handles partial-period pay.
Is retro pay taxed?
Yes. The IRS treats retro pay as supplemental wages, so it is subject to federal income tax (commonly the flat 22% supplemental method or the aggregate method), plus Social Security and Medicare. State income tax usually applies too.
What tax rate is used on retro pay?
Employers commonly use the 22% flat supplemental rate for federal income tax, rising to 37% on any portion above $1,000,000 in supplemental wages for the year. On top of that, FICA takes 6.2% Social Security (up to the $184,500 wage base) and 1.45% Medicare, for 7.65% combined. The bonus tax calculator uses the same supplemental treatment.
Does retro pay include overtime?
It can. If overtime hours were paid at the old rate, the retro is the difference between the old and new overtime rates on those hours. The overtime pay calculator works out the corrected overtime rate first.
When will I receive retro pay?
Retro pay is typically added to the employee's next regular paycheck as a separate line, though timing depends on your employer's payroll cycle and how quickly the correction is processed.
What does "retro" mean on my pay stub?
A "retro" line is retroactive pay: the corrected wage difference from a prior period. It is taxed like your other wages, which is why the gross figure and your take-home differ.