A retrocalculation is the recalculation a payroll engine runs when a prior pay period has to be corrected.
Retrocalculations are triggered by backdated salary changes, corrected hire or termination dates, absence adjustments, benefit election changes and retroactive cost-center moves. The payroll engine recalculates the affected periods and statutory deductions, then creates new retro records beside the original records.
One change in the HR system can produce dozens of records in the payroll system. Reading those retro records back correctly requires payroll-specific logic that iPaaS recipes and unified APIs do not include.
