As of supply of services, it generally takes place on the earliest of dates:
• when the services were performed;
• when (and to the extent) the services had been paid for;
• when a tax invoice for supply was issued.
In relation to continuous supply of services, a supply will take place each time a payment was made or on the payment date specified on the invoice issued, whichever is the earlier, and at least once in every twelve month period.