Article 11 Calculation of the payments on accountI1

Subject to paragraph (2) below and articles F112A, 13, 14 and 15 below, the amount of each payment on account to be made by a taxable person who falls within article 5 above shall equal F2one twenty-fourth of the total amount of tax, F3... which he was liable to pay in respect of the prescribed accounting periods the ends of which fell within the period (in this Order referred to as “the reference period”)—

The reference in paragraph (1) to the “total amount of tax” includes only tax that is required to be, or has been, accounted for on a return for a prescribed accounting period.

Where in the period of the year mentioned in sub-paragraph (a), (b) or (c) of paragraph (1) above a prescribed accounting period of the taxable person did not begin on the first day or did not end on the last day of a month, the reference period shall, for the purpose of paragraph (1), be regarded as having comprised those prescribed accounting periods which related to the tax periods ending within the period of the year mentioned in sub-paragraph (a), (b) or (c) of paragraph (1) as appropriate to which references are shown in the certificate of registration issued to him.