Retro Pay Calculator

The difference between the new and old rate × the hours paid at the old rate. A raise from $18 to $20 backdated over 160 hours is $320; 10 overtime hours add 10 × 1.5 × $2 = $30.

Pay owed because a raise took effect before payroll started paying it. A $4,000 salary raise effective September 1 but first paid November 1 owes 61 days of the difference: $4,000 × 61 ÷ 365 = $668.49.

Not quite. Retro pay makes up the difference after a raise; back pay is wages that were never paid at all, such as missed hours or unpaid overtime.

As wages. Social Security and Medicare apply, and federal income tax may be withheld at the 22% flat rate for supplemental wages paid separately.

Yes. Overtime hours worked in the period must be recomputed at 1.5 times the new rate, so they carry one and a half times the difference (29 CFR 778.303).

Yes, when it was promised or tied to work, hours or output. It belongs to the weeks it covers, so each week's regular rate goes up by its share ÷ the hours worked, and the overtime already paid is short by half of that for each overtime hour (29 CFR 778.209). A $1,040 bonus over 13 weeks of 45 hours with 5 overtime hours owes $57.78 more.