How to Calculate Retro Pay for a Raise (Hourly and Salary)

What is retro pay and when is it owed?

Retro pay, also called retroactive pay or back pay, is money owed for an earlier period because you were paid less than you should have been. The usual causes are a raise or contract increase that was approved after its start date, a payroll error, or a rate that was entered wrongly. It is paid as a lump sum, and it counts as ordinary wages.

The amount depends on three things: the old rate, the new rate, and the date the new rate took effect. Retro pay covers every pay period from that date up to the first paycheck that already had the new rate in it. Nothing is owed from that paycheck onward.

How do you calculate retro pay for an hourly employee?

Subtract the old rate from the new rate, then multiply by every hour paid at the old rate, counting overtime hours at 1.5 and double-time hours at 2. The multipliers are there because a retroactive raise also raises the regular rate, and the overtime premium follows the regular rate.

Take a raise from $20 to $22 that applies to 160 regular hours and 20 overtime hours. The raise is $2, so straight-time back pay is $2 × 180 hours = $360.00. The extra half for the 20 overtime hours is $2 × 0.5 × 20 = $20.00. The total owed is $380.00.

If the raise changed in steps, calculate each step on its own hours and add the results. Do the same for each pay period when the hours differ.

How do you calculate retro pay for a salaried employee?

Divide the old and the new annual salary by the number of pay periods in a year, take the difference, and multiply by the number of paychecks that were paid at the old salary.

A raise from $52,000 to $54,600 on a biweekly schedule changes each paycheck by $100.00. If four paychecks went out at the old salary, the retro pay is $400.00. If you are given calendar dates instead of a count, count the paydays that fall between the effective date and the first correct paycheck.

A salaried employee who is exempt from overtime has no overtime true-up. A non-exempt employee paid a salary for fixed hours does, and should be treated like the hourly case once the hourly rate is worked out.

Why does overtime belong in retro pay?

The federal regulation on retroactive increases says that when a raise is paid for an earlier period, the regular rate for that period changes too, so overtime has to be recomputed at the new rate. Each overtime hour is owed the raise at the overtime multiple, not only at straight time.

This is the most common reason a retro check comes up short. Payroll multiplies the raise by total hours and stops, which leaves out the extra half of the raise on every overtime hour. Paid leave is different: it is paid at the new rate too, but it does not count as hours worked for overtime.

How is a retro pay check taxed?

A retro check is wages. Social Security at 6.2% and Medicare at 1.45% apply in full, and federal income tax is withheld either at the flat 22% supplemental rate, when the payment is made separately, or by adding it to a regular paycheck and using the percentage method. On a $1,000.00 retro check paid separately with no state tax, withholding is about $296.50 and take-home about $703.50.

Social Security stops once your wages for the year pass $184,500 in 2026, and Medicare adds 0.9% on wages over $200,000. Withholding is a prepayment: the tax you really owe is settled when you file your return, so a heavily taxed retro check is not a permanent loss.

How do you check a retro check against your pay stub?

1. Find the line on the stub marked retro, back pay or adjustment, and note the amount.
2. Write down the old rate, the new rate, the effective date and the hours in each pay period since then.
3. Work out the total with the formula above, or enter the periods in the calculator.
4. If your figure is higher, ask payroll for the hours, rates and start date they used. The usual gaps are a missing overtime true-up, a wrong start date and a skipped mid-period step raise.

Common questions

Sources

Reviewed on 25 Oct 2026 against the published sources below. Laws and prices change, so check the current position before you rely on a figure.

• 29 CFR 778.303: Retroactive pay increases
• 29 CFR 778.106: Time of payment of overtime
• IRS Publication 15-T (2026): Federal Income Tax Withholding Methods
• IRS Publication 15 (2026): Employer’s Tax Guide (supplemental wages)
• SSA: Contribution and benefit base

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