(1) Where, on the determination of an appeal against an assessment made on a chargeable person for a chargeable period, the amount of tax payable by the person for the period is in excess of the amount of the tax which the chargeable person had paid before the making of the appeal, the excess shall be deemed to be due and payable on the same date as the tax charged by the assessment is due and payable.

(2) Notwithstanding subsection (1), where -

(a) the amount of tax which the chargeable person had paid before the making of the appeal is not less than 90 per cent of the amount of tax found to be payable on the determination of the appeal, and

(b) the tax charged by the assessment was due and payable in accordance with section 959AO(2), section 959AQ, section 959AR(3) or section 959AS(3), as the case may be,

the excess referred to in subsection (1) shall be deemed to be due and payable not later than one month from the date of the determination of the appeal.