Retroactive Pay Calculator
Back pay when a raise or a pay correction reaches back to earlier paychecks — hourly or salaried, overtime included, with a rough take-home estimate and the journal entry.
Ben / Reviewed Sep 27, 2026 / v2.0.0
Results
Showing the numbers you calculated- Back pay owed
- $1,974.00
- Before taxes
- Estimated take-home
- $1,388.71
- After about $585.29 withheld
- Short on each paycheck
- $240.00
- Times 8 paychecks
- Overtime back pay
- $54.00
- The raise × the overtime rate, for every overtime hour
- The raise is worth
- $6,240.00
- A year — a 13.64% raise
- Cost to the employer
- $2,125.01
- Plus the employer's Social Security and Medicare
How the back pay adds up
| How | Amount | |
|---|---|---|
| Regular pay | 8 paychecks × $240.00 ($2,000.00 − $1,760.00) | $1,920.00 |
| Overtime | 12 hours × $3.00 raise × 1.5 | $54.00 |
| Back pay for the period | — | $1,974.00 |
Estimated withholding
The real numbers depend on your W-4, your state, and how the employer runs the payment.
| Rate | Amount | |
|---|---|---|
| Federal income tax | 22.00% | $434.28 |
| Social Security | 6.20% | $122.39 |
| Medicare | 1.45% | $28.62 |
| Total withheld | — | $585.29 |
| Take-home | — | $1,388.71 |
Journal entry (for the employer)
If the back pay was accrued earlier, debit Accrued wages instead of Wages expense.
| Account | Debit | Credit |
|---|---|---|
| Pay the back wages | ||
| Wages expenseRetroactive pay | $1,974.00 | |
| Payroll tax expenseEmployer's Social Security and Medicare | $151.01 | |
| CashNet check to the employee | $1,388.71 | |
| Federal income tax withheld | $434.28 | |
| Social Security and Medicare payableEmployee and employer shares | $302.02 | |
| Totals | $2,125.01 | $2,125.01 |
What this does
When a raise gets backdated — or someone finds out they've been paid the wrong rate — the paychecks already issued have to be made up. This works out by how much.
It handles hourly or salaried pay, gives overtime hours their share of the raise, takes off any retro pay already paid, and estimates what's left after withholding.
How the math works
short per paycheck = new pay per paycheck − old pay per paycheck regular back pay = short per paycheck × paychecks at the old pay
Hourly paychecks are the rate × regular hours. Salaried paychecks are the annual salary ÷ paychecks per year.
overtime back pay = overtime hours × (new rate − old rate) × overtime rate
Federal rules treat a backdated raise as raising the regular rate for the whole period, so each overtime hour is owed 1.5× the raise — not just the raise (29 CFR 778.303).
still owed = regular + overtime + other back pay − retro pay already received
Withholding is an estimate: federal at the supplemental rate you enter, Social Security and Medicare, and state.
Check my math: a worked example
$22.00 → $25.00 an hour, backdated 8 paychecks (paid every two weeks) with 80 regular hours each and 12 overtime hours in all.
- Each paycheck should have been $2,000.00, not $1,760.00 — $240.00 short.
- 8 paychecks × $240.00 = $1,920.00.
- Overtime: 12 hours × $3.00 × 1.5 = $54.00.
- Back pay owed: $1,974.00. After roughly $585.29 of withholding, about $1,388.71 lands in the bank.
These numbers come straight from the calculator using its example inputs — if the math ever changes, this example changes with it.
Mistakes I see a lot
- Adding what was already paid on top of the old pay. That counts the same money twice — back pay is the difference, and only retro pay already received comes off it.
- Forgetting overtime. A backdated raise is owed on every overtime hour at the overtime rate.
- Mixing up every two weeks (26 paychecks) and twice a month (24).
- Counting a partial pay period as a whole one.
- Expecting the whole amount in the bank. Back pay is taxed like any other pay, and in its own check federal withholding is often a flat 22%.
Questions people ask
- Is retro pay taxed differently?
- It's taxed the same as any other wages — it's just withheld differently. Paid in its own check, the employer can withhold federal tax at a flat 22%. Added to a regular paycheck, it's withheld as if you earned that much every period, which often takes more. Either way, the real tax gets settled on your return.
- Which year's W-2 does it go on?
- The year it's paid, not the year it was earned. Back pay for last year that's paid in March goes on this year's W-2.
- I'm salaried but get overtime. What do I use?
- Switch to hourly and use your salary's hourly equivalent — for a salary meant to cover 40 hours a week, that's the weekly salary ÷ 40 — so your overtime hours get their share of the raise.
- Can an employer take back an overpayment?
- Sometimes, but the rules vary a lot by state, and many require the employee's written agreement first. Check your state's rules before deducting anything.
- How far back can back pay go?
- Under federal wage law, claims generally reach back two years — three if the violation was willful. A contract, union agreement, or settlement can set its own period.
Assumptions and limits
- Back pay for each paycheck = what it should have been at the new pay − what it was at the old pay. Hourly paychecks are rate × regular hours; salaried paychecks are the annual salary ÷ paychecks per year, each rounded to the cent.
- A partial paycheck is entered as a fraction (half a pay period = 0.5) and prorated evenly.
- A retroactive raise raises the regular rate for the whole period, so every overtime hour in it is owed the raise times the overtime rate (29 CFR 778.303).
- Retro pay already received is subtracted from what's owed. "Other back pay owed" is added as entered.
- Withholding is an estimate for supplemental wages: federal at the rate entered (22% is the optional flat rate — Treas. Reg. §31.3402(g)-1), Social Security 6.2% unless the year's pay is past the wage base, Medicare 1.45%, and state at the rate entered. Additional Medicare Tax and local taxes aren't included.
- The employer's cost adds its matching Social Security and Medicare. Federal and state unemployment tax aren't included — whether they apply depends on what's already been paid this year.
Disclaimer: Educational and planning use only. Results depend on what you enter and may not match your lender, your tax return, or professional accounting treatment. Informational content + opinions only — not tax/legal advice.