166.—(1) Where a part-week—
(a)is the whole period for which an employment and support allowance is payable, or occurs at the beginning of an award, the relevant week is the period of 7 days ending on the last day of that part-week; or
(b)occurs at the end of an award, the relevant week is the period of 7 days beginning on the first day of the part-week.
(2) Where a claimant has an award of an employment and support allowance and that claimant's benefit week changes, for the purpose of calculating the amounts of an employment and support allowance payable for the part-week beginning on the day after the last complete benefit week before the change and ending immediately before the change, the relevant week is the period of 7 days beginning on the day after the last complete benefit week.