How do auditors check population completeness before testing?

Auditors check completeness by comparing the population to an independent source. Examples include reconciling record counts to a system report, reconciling totals to the general ledger, confirming extraction parameters, reviewing filters, and checking whether all relevant periods, locations, statuses, and transaction types are included.

The right check depends on the audit objective. If the procedure tests terminated-user access, completeness may mean every termination during the period. If the procedure tests refund approval, completeness may mean every refund transaction above the threshold.

Testing before completeness work creates false comfort. A clean sample from an incomplete population cannot support a broad conclusion.