Free Retro Pay Overtime Calculator (Hourly & Salary) 2026

Page last updated 25 Oct 2026

How to use the retro pay overtime calculator

Choose hourly or salary. For hourly pay, add one row for each pay period with the old rate, the new rate and the regular, overtime and double-time hours worked in it.
For a salary, enter the old and new annual pay, the pay frequency and either the number of paychecks owed or the start and end dates.
Read the total, and the split between straight-time back pay and the overtime true-up, then open the tax view to see what the lump sum leaves after withholding.
Compare the result with the retro line on your pay stub. If it is lower, ask payroll for the hours, rates and start date they used. You can print the result or download it as a CSV.

How is retro pay calculated?

Retro pay is the new rate minus the old rate, times the regular hours, plus 1.5 times the overtime hours and 2 times the double-time hours, added up over every pay period you enter. For a salary it is the difference in pay per paycheck times the paychecks owed, counted by periods or by calendar dates. The tax view applies the flat 22% supplemental rate or the Publication 15-T percentage method, then Social Security up to $184,500, Medicare and the state rate you enter.

For example, a raise from $20 to $22 an hour that applies to 160 regular and 20 overtime hours owes $2 × 180 = $360.00 in straight-time back pay plus $2 × 0.5 × 20 = $20.00 for the overtime premium, $380.00 in all. A $1,000 retro check paid separately, with no state tax, withholds about $296.50 and leaves about $703.50. The rates and hours are made up; yours come from what you type.

Who should use the retro pay overtime calculator

Employees checking a back-pay check after a raise or a new contract
Payroll and HR staff working out a retroactive increase for non-exempt staff
Anyone paid at the wrong rate for part of a year who wants the difference in dollars
Workers who want to know what a retro check leaves after tax

Who should not use this

Anyone claiming overtime that was never paid at all; this tool prices a rate change, not missing hours
Anyone who needs an exact payroll tax filing figure; use your payroll provider for that
Exempt employees on salary, who have no overtime true-up; use the salary mode and ignore the overtime boxes

Limitations

Federal income tax follows the 2026 IRS percentage method; state and local tax is only as accurate as the rate you enter.
It assumes the raise applies to every hour in the period you enter.
Contract rules about which periods and hours are covered are not read; check your agreement.
It does not decide whether an employer may recover an overpayment; that depends on state law.
Nothing is uploaded or stored on a server. Clearing your browser data also removes the saved profile.

What this calculator does that others don’t

This calculator covers the parts of back pay that simple versions skip: several rate steps, the overtime true-up, salary pay by paycheck or by date, and what is left after tax. In short, it offers:

Several pay periods and rate steps in one result, with a percent-raise helper.
Overtime and double-time true-up, as 29 CFR 778.303 requires.
Salary mode by pay periods or by calendar dates.
Net retro check after 2026 federal withholding, FICA and state tax, with flat 22% or aggregate method.
Negative results for overpayments, print view and CSV download.

The retro pay formula

Retro pay is the pay you should have received minus the pay you did receive, added up over every affected hour or paycheck. The two formulas are:

Formula hourly: retro = (new rate − old rate) × (regular hrs + 1.5 × OT hrs + 2 × double-time hrs); salary: retro = (new pay − old pay per paycheck) × paychecks owed

Worked example: a raise from $20 to $22 with 160 regular and 20 overtime hours. Straight-time back pay is $2 × 180 = $360.00. The overtime true-up is $2 × 0.5 × 20 = $20.00. Total $380.00.

Why overtime is part of 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 is changed too. Each overtime hour is therefore owed the raise at the overtime multiple, not at straight time. The same applies to double time where it is paid.

How a retro check is taxed

Retro pay is wages. Federal income tax is withheld at 22% if the payment is separate, or by adding it to a regular paycheck and applying the Publication 15-T percentage method. Social Security stops once your year-to-date wages pass $184,500 in 2026; Medicare has no cap and adds 0.9% over $200,000.

Common mistakes

Most short retro checks come from the same few errors in the hours, the rates or the dates, so check these before you accept a figure:

Using the new rate for overtime but only paying straight time on the raise.
Forgetting step raises that happened in the middle of the period.
Counting paid leave as overtime hours.
Applying the raise to the wrong start date. Check the effective date, not the date the contract was signed.

Sources and review

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

Common questions

How do I calculate back pay for a raise?

Subtract the old rate from the new rate, then multiply by every hour worked at the old rate during the affected period. A raise from $20 to $22 over 80 hours is $2 × 80 = $160.00. If overtime was worked, add the overtime true-up (see below). For a salary, subtract the old pay per paycheck from the new one and multiply by the number of paychecks.

What does retro pay mean?

Retro pay (retroactive pay or back pay) is money owed for an earlier period because a raise, contract, correction or payroll error means you were paid less than you should have been. It is paid as a lump sum and is taxable wages.

How do I calculate retro pay for hourly employees?

Retro pay = (new rate − old rate) × (regular hours + 1.5 × overtime hours + 2 × double-time hours). The 1.5 and 2 are there because a retroactive raise also raises the regular rate the overtime premium is based on (29 CFR 778.303). Example: $20 to $22, 160 regular hours and 20 overtime hours = $380.00.

How do I calculate retro pay for salary employees?

Divide the old and new annual salary by the number of pay periods, take the difference and multiply by the paychecks that were underpaid. $52,000 to $54,600 on a biweekly schedule is $100.00 per paycheck, so four paychecks owe $400.00.

Is there a retroactive pay calculator for Excel?

Yes. Put the old rate in A2, new rate in B2, regular hours in C2, overtime hours in D2 and double-time hours in E2, then use =(B2-A2)*(C2+1.5*D2+2*E2). For a salary use =(NewAnnual-OldAnnual)/PeriodsPerYear*PeriodsOwed. The calculator above also downloads a CSV you can open in Excel.

How is a salary increase and retro pay calculated together?

Work out the new pay per paycheck first, then the retro amount for the paychecks that were paid at the old salary. From the first correct paycheck on, you are paid the new salary and no further retro is owed.

Does retro pay include overtime?

Yes, for non-exempt employees. A raise made retroactive raises the regular rate for every workweek in the period, so each overtime hour is owed the raise at 1.5 times. Skipping this is a common reason retro checks are short.

How is a retro pay check taxed?

It is ordinary wages. Social Security (6.2%) and Medicare (1.45%) apply in full, and federal income tax is withheld either at a flat 22% when the payment is made separately or by adding it to your regular paycheck (aggregate 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.

Why does my retro check look so heavily taxed?

Withholding is a prepayment, not your final tax. Under the aggregate method a lump sum is treated as if you earned that much every paycheck, which pushes the withholding up. The real tax is settled when you file your return.

What if I was overpaid and the number is negative?

Switch the rates around or enter a lower new rate: the calculator shows a negative result. Whether and how an employer may recover an overpayment from wages depends on state law, and some states limit or forbid it.

Do I include paid time off and holidays?

Include any paid hours that were paid at the old rate. Paid leave hours are normally paid at the same rate as worked hours, so they are part of the back pay, but they do not count as hours worked for overtime.

How do I calculate retro pay for a union contract raise?

Use the effective date and raise in your contract. For a percentage raise, enter the percent in the box above to fill in the new rate, and add one row for each pay period (or each step) that the contract covers. Your contract decides which periods and which hours are included, so check it for the exact wording. This applies to any union agreement, including SEIU locals.

When does the employer have to pay retro pay?

Federal law does not set one date for contract raise back pay. For unpaid overtime, the employer must pay it as soon as the amount can be worked out and no later than the next regular payday after that (29 CFR 778.106). State wage laws can be stricter, so ask your payroll department or your state labor agency.

Guides that explain the rules

Related tools

Results are estimates, not legal, tax, payroll or financial advice. They follow the rules and rates named under Sources, leave out anything the page does not mention (such as other income, credits, local rules or your employer’s own policy), and can differ from a payroll run, a tax return or an agency’s decision. See the disclaimer. Found a mistake? Report an error in a calculation.