Retro Pay Calculator
Enter the old rate, corrected rate, and affected hours. See gross retro pay and an estimated withholding breakdown.
Try a scenario
Your inputs
Retro pay owed
$400.00
($25.00 − $20.00) × 80.0 hours
Did this period include FLSA overtime hours?
If these hours included overtime, the rate correction also changes the overtime premium.
Estimated withholding
- Federal supplemental (22% flat)
- −$88.00
- FICA — Social Security + Medicare (7.65%)
- −$30.60
- State (Other state — variable rate)
- Varies — see note
- Net retro pay (after federal + FICA only)
- $281.40
State assumptions
Your state uses a bracketed schedule or a separate supplemental rate — your employer's payroll system handles the calculation. The calculator shows the federal-only number; check your state's Department of Revenue withholding instructions for the exact state amount.
State DOR withholding instructions (varies by state)
Withholding is an estimate. Bracketed states show federal and FICA only. How the calculation works
Common questions
What is retro pay?
Retro pay is the difference between what an employee was paid and what they should have been paid for earlier work. A common case is a raise that took effect before payroll updated the rate. The basic calculation is (correct rate − paid rate) × affected hours.
Is retro pay taxed differently from regular pay?
The IRS treats retro pay as wages. Employers often use the 22% supplemental-wage method for federal withholding, but that is a paycheck estimate, not the employee’s final tax rate. The employee’s annual tax return reconciles the difference.
What's the difference between retro pay and back pay?
People often use the terms interchangeably. Retro pay usually means correcting earlier work that was paid at the wrong rate. Back pay can also describe wages owed after a dispute or missed payment. This calculator handles a rate difference across known hours.
Does my state have to follow the 22% federal supplemental rate?
No. The 22% rate is federal. This calculator directly models no-income-tax and flat-rate states. Bracketed states need details the tool does not collect, so it shows a federal-only estimate and tells you the state amount varies.
What if the rate change covered overtime hours?
If affected hours included overtime, the rate difference applies to all hours and the overtime premium must also be recomputed. Enter the affected overtime hours and the calculator adds 0.5 × the rate difference × overtime hours under 29 CFR §778.303.
My employer paid the bonus late — does that trigger retro pay?
A late non-discretionary bonus can change the regular rate and the overtime premium for the period it covers. That is a different calculation under 29 CFR §778.209, so this rate-change calculator does not model it.
How accurate are the California and New York state withholding estimates?
California is estimated at its 6.6% supplemental rate, although an employer may use the aggregate method instead. New York is estimated at the 11.7% state rate and does not include New York City or Yonkers withholding. Actual payroll can therefore differ.
How is FICA handled?
The calculator estimates FICA at 7.65%: 6.2% Social Security plus 1.45% Medicare. Social Security withholding stops at the annual wage base, so actual FICA can be lower for an employee who has already crossed it.
Clockspot keeps clock-ins, corrections, approvals, and payroll-ready hours connected so owners and managers can review the workweek before payroll.
Keep time records, pay rates, and payroll exports connected before payroll runs. See how Clockspot tracks rate changes.