U.S. Customs and Border Protection (CBP) cannot ensure its Entry Reconciliation Program reporting is accurate or complies with requirements. Specifically, CBP did not always validate importers’ self-reported final values of imports when it assessed duties and fees because it did not require importers to substantiate self-reported merchandise values with source documentation. In addition, CBP did not always follow its policies when conducting reviews of reconciliation entries because its Standard Operating Procedures had been implemented differently across all ports of entry. Finally, CBP missed opportunities to collect additional revenue when it did not assess monetary liquidated damages for importers that filed reconciliation entries late or not at all. This occurred because CBP’s controls were insufficient to ensure the ports properly assess liquidated damages for importers who file reconciliations late or not at all. CBP’s actions compromised the integrity of the Entry Reconciliation Program and, as such, may have put approximately $751 million of revenue, in the form of reconciliation refunds, at risk. We made four recommendations to improve the overall effectiveness of the program. CBP concurred with three of our four recommendations.