Back Pay Calculator
Updated August 2026 · Free · No sign-up
Calculate back pay — wages you were owed but not paid: underpaid rates, missed overtime, misclassification, or a raise applied late. Get the owed amount, plus the liquidated-damages doubling many claims qualify for.
Quick answer: Back pay = (correct pay − actual pay) × affected periods. Underpaid $1.50/hour for 40 hrs/week over 26 weeks = $1,560 owed — and FLSA claims often add an equal amount in liquidated damages, doubling recovery to $3,120.
The Formula
Back Pay = (Correct Rate − Paid Rate) × Hours per Week × Weeks Affected
The same structure covers every scenario — swap in the right "correct rate": the legal minimum wage, your contract rate, the time-and-a-half rate for unpaid overtime, or the new salary from a raise that HR processed late.
Worked Examples
Example 1 — underpaid rate. Owed $20.00, paid $18.50, 40 hrs/wk for 26 weeks: $1.50 × 40 × 26 = $1,560. With FLSA liquidated damages: $3,120.
Example 2 — unpaid overtime. 5 OT hours/week paid at straight $18 instead of $27 (time and a half): $9 × 5 × 52 = $2,340/year — doubled, $4,680. Misclassified "salaried" workers doing non-exempt work accumulate this silently.
Example 3 — late raise. Raise to $65,000 effective March 1, processed May 1: ($65,000 − $60,000) ÷ 26 × ~4.3 pay periods = $827 owed — the most common and most quietly fixed back-pay case; just email payroll with the math.
Example 4 — minimum wage violation. Paid $12 in a $15 state, 35 hrs/wk, 40 weeks: $3 × 35 × 40 = $4,200, before state penalties that often exceed the wages themselves.
Back Pay vs Retro Pay
Usage overlaps, but the practical line: retro pay is an employer correcting its own delay (late raise, payroll error) — see the retro pay calculator for that math per paycheck. Back pay is the broader legal remedy for wages wrongfully unpaid — minimum wage, overtime, misclassification, wrongful termination awards.
Time Limits (Act Before the Clock Runs)
| Claim | Lookback window |
|---|---|
| FLSA (federal minimum wage / OT) | 2 years — 3 if the violation was willful |
| State wage claims | Commonly 3-6 years (varies; NY 6, CA 3-4 via UCL) |
| Contract-based claims | State contract statute — often 4-6 years |
Liquidated Damages: The Doubling Rule
FLSA claims presumptively add liquidated damages equal to the unpaid wages — not a penalty for you to prove, but a default the employer must escape by showing good faith. Many state laws stack their own penalties on top (waiting-time penalties in California can add up to 30 days of wages for final-paycheck violations — related math in the final paycheck calculator).
How to Pursue It (Escalation Ladder)
- Payroll/HR first, in writing, with your spreadsheet: most underpayments are errors, and documented math gets fixed in one cycle.
- State labor department wage claim: free, no lawyer needed, effective for clear-cut cases.
- US DOL Wage and Hour Division: for FLSA violations; can supervise settlements including liquidated damages.
- Private suit: for larger claims — FLSA awards attorney fees to winning employees, which is why employment lawyers take strong wage cases on contingency.
Evidence to keep: pay stubs, timesheets or personal hour logs (courts accept reasonable employee reconstructions when the employer kept poor records), the offer letter or raise email, and job descriptions for misclassification claims.
Tax Treatment
Back pay is wages — taxed in the year received, with normal withholding and FICA. A large multi-year award landing in one tax year can push marginal dollars into a higher bracket; the liquidated-damages half is also taxable income (as are most employment-award components except certain physical-injury damages).
Frequently Asked Questions
How do I calculate back pay?
(Correct rate − paid rate) × affected hours per week × weeks. For unpaid overtime, the correct rate is 1.5× your regular rate for the OT hours.
What are liquidated damages in a wage claim?
An amount equal to the unpaid wages, added by default in FLSA cases unless the employer proves good faith — effectively doubling recovery.
How far back can I claim unpaid wages?
FLSA: 2 years (3 if willful). State laws often reach further — 3 to 6 years. The window runs continuously, so delay erases the oldest weeks first.
What is the difference between back pay and retro pay?
Retro pay is an employer correcting its own processing delay; back pay is the legal remedy for wrongfully unpaid wages (minimum wage, OT, misclassification).
Is back pay taxed?
Yes — as ordinary wages in the year received, including FICA. Large multi-year awards concentrated in one year can hit higher marginal brackets.
Do I need a lawyer for a back pay claim?
Not for small, clear cases — payroll or a state wage claim handles those free. For large or contested claims, FLSA fee-shifting makes contingency representation accessible.
✓ Formula verified • Last updated: August 20, 2026