Furnishing details of inward supplies requires electronic monthly submission and reconciliation by registered persons with prescribed communication rules. Registered persons, excluding Input Service Distributors, non-resident taxable persons and certain persons under specified payment schemes, must electronically furnish, within the prescribed post-period monthly window, details of inward taxable supplies including reverse charge and integrated-taxable supplies and related credit or debit notes, and must verify, modify, include or delete supplier-communicated outward-supply details. Modifications by recipients must be communicated to suppliers as prescribed. Where details remain unmatched, taxpayers must rectify errors in the period noticed, pay tax and interest if applicable, and observe the statutory cut-off for rectifications.