Time of Supply Rules:
Clause (a) of Section 13(2): Time of supply is the date of invoice or date of payment receipt, whichever is earlier, if the invoice is issued within the prescribed period.
Clause (b) of Section 13(2): If the invoice isn't issued on time, the time of supply is the service provision date or payment receipt date, whichever is earlier.
Invoice Issuance: For continuous services, invoices must be issued by the specified date or upon completion of an event, as per Section 31(5).