4Profits tax for any chargeable accounting period falling partly before and partly after the said end of March shall be apportioned between the two parts of the period and—
(a)the credit by way of unilateral relief to be applied in reducing the amount of the profits tax for that period shall not exceed so much of the profits tax as is apportioned to the second part of the period; and
(b)paragraph 3 of this Part of this Schedule shall apply in relation to so much of the profits tax as is apportioned to the first part of the period as it applies in relation to profits tax for a chargeable accounting period ending at or before the said end of March.