85. Notwithstanding section 82, where consideration for a taxable supply is paid or becomes due on more than one day, tax under section 16 in respect of the supply is payable on each day that is the earlier of the day a part of the consideration is paid and the day that part becomes due.
The tax that is payable on each such day shall be calculated on the value of the part of the consideration that is paid or becomes due, as the case may be, on that day.