Off-Cycle Pay Correction After Retro Raise
A US-based employee in Illinois received a merit increase from $60,000 to $63,000 effective the first day of the prior pay period, but payroll processed the raise one period late because the change was entered after the pay run cutoff. The employee was paid at the old rate for one full biweekly period. The next regular pay run is in nine days. The employee has a garnishment order (25% of disposable earnings) and a 401(k) deferral of 6%. The manager asks payroll to 'just add the difference to the next check.' Payroll also notices the employee's year-to-date gross now exceeds the Social Security wage base threshold by a small margin.
1. How should payroll correct the underpayment, and what must be considered before adding a lump sum to the next check?
Read the worked answer
The correction is a retroactive pay adjustment for one biweekly period: $3,000 annual raise / 26 periods ≈ $115.38 of missed regular wages. Payroll should process it as a separate off-cycle or supplemental line, clearly labeled, with the correct effective date so the earnings land in the right period for reporting.
Before adding it to the next check, consider:
- Garnishment: the withholding is 25% of disposable earnings per period. A lump sum increases that period's disposable earnings, so the garnishment calculation must be recomputed on the combined amount, not simply added on top of the prior period's deduction. Some jurisdictions also cap total deductions per period.
- 401(k): the deferral applies to eligible compensation; the retro amount is eligible, so the 6% should be applied and the employer match trued up.
- Tax withholding: supplemental wages may be taxed at the flat supplemental rate or aggregated, depending on method; the employee should not be over- or under-withheld relative to the regular rate.
- Timing: correcting on the next regular run is acceptable if within the employer's normal correction window and state prompt-payment rules; otherwise an off-cycle run is warranted.
The manager's 'just add it' instruction is the wrong frame - each deduction must be recomputed on the corrected earnings.
2. What is the significance of the Social Security wage base issue, and how should payroll handle it?
Read the worked answer
Once cumulative wages exceed the Social Security wage base for the year, no further OASDI employee or employer tax is withheld on wages above the base. If the retro adjustment pushes YTD gross over the base, the additional wages should be subject to Medicare only (and the additional Medicare tax if applicable), not Social Security.
Payroll must:
- Verify the exact YTD taxable wages against the wage base before computing the retro line - do not assume.
- Apply OASDI only up to the remaining room under the base; any excess is Medicare-only.
- Confirm the prior periods were taxed correctly, since a late raise means earlier checks may already have been miscomputed.
- Reconcile the YTD totals after the correction so W-2 reporting at year-end is accurate.
The judgment point: a small overage looks trivial but creates a W-2 mismatch and a refund/credit headache if not split correctly at the line level.