ACE (Automated Commercial Environment)

ACE is CBP's electronic 'single window' system through which all US import and export entries are filed, tracked, and reconciled. Customs brokers transmit entry data — HTS codes, values, 9903 trade-remedy codes, and duty calculations — into ACE, and CBP uses it to assess duty, liquidate entries, and run programs like Reconciliation. Example: a broker files your 7501 entry summary in ACE, and the eventual liquidation and any refund also post there. It matters because ACE is the system of record for what was declared and charged on every entry — the data trail you rely on to verify duty or pursue a refund.