Reconciling payroll data to external providers is a critical step in retirement plan administration. While the general ledger (Option A) and payroll register (Option B) confirm that the company calculated and " expensed " the match correctly in its own books, they cannot confirm that the funds actually reached the employee ' s individual investment account. The plan administrator reports (Option D) are the only source that shows what was actually posted to the employee’s account at the financial institution. By comparing these external reports to the internal payroll register, payroll professionals can identify discrepancies caused by transmission errors, data mapping issues, or eligibility timing differences. This ensures compliance with ERISA requirements for timely and accurate deposit of retirement contributions and matches.