83. The consideration, or a part thereof, for a taxable supply is deemed to become due on the earliest of(1) the earlier of the day the supplier first issues an invoice in respect of the supply for that consideration or part and the date of that invoice,
(2) the day the supplier would, but for an undue delay, have issued an invoice in respect of the supply for that consideration or part, and
(3) the day the recipient is required to pay that consideration or part to the supplier pursuant to an agreement in writing.
Notwithstanding the first paragraph, where property is supplied by way of lease, licence or similar arrangement under an agreement in writing, the consideration, or any part thereof, for the supply is deemed to become due on the day the recipient is required to pay the consideration or part to the supplier pursuant to the agreement.