Acknowledgement Number and Transaction ID govern GST return submission, with validation locking the Transaction ID after verification. On GST return submission the system issues a unique Acknowledgement Number and, for offline-prepared returns, a provisional Transaction ID while GSTN validates personal ledger carry-forward cash, input tax credit and tax payment details; final acknowledgement, which locks the Transaction ID, is generated after validation and records the acknowledgement number and timestamp, Transaction ID and timestamp, GSTIN, tax period, and totals for gross supplies, taxable supplies and taxes paid or refund claimed by tax type.