Time of supply of services: tax liability arises on the earliest of invoice, payment, provision, or recipient record. The section fixes the time of supply of services as the trigger for tax liability: generally the earliest of invoice issuance (if timely) or receipt of payment, or provision of service or recipient's book entry where invoicing is not timely. For reverse charge supplies, time of supply is the earlier of recipient's payment entry or a date following a specified period after invoice issue, with fallback to recipient's book entry and a special rule for cross-border associated enterprises. Voucher supplies use issue or redemption dates. Where none apply, return filing date or tax payment date governs; additions like interest are taxed on receipt.