Time of supply rules determine GST liability based on the earlier of invoice issuance or receipt of payment and special cases.
The Time of Supply fixes GST liability by reference to invoice or receipt of payment, using the earlier of those events when invoices are timely; late invoicing, reverse charge, vouchers, continuous supplies, additions to supply, and rate changes have specified alternative or fallback dates, and receipt of payment is the earlier of book entry or bank credit. (AI Summary)