Time of supply for HAM highway services: invoice date or receipt of payment determines tax liability. Time of supply for HAM concession contracts treating construction plus O&M as a single continuous supply is the invoice issuance date or receipt of payment, whichever is earlier, when the invoice is issued on or before the contractually specified date or event; otherwise the time of supply is the date of provision of service (or contractual due date of payment) or receipt of payment, whichever is earlier. Interest component in installments is includible in taxable value.