10. The amount of the business profits tax payable by any person, before taking into account any credit that may be due under an agreement referred to in section 49AA of the Income-tax Act, 1922, for any chargeable accounting period shall, in computing total income for the purposes of the relevant income-tax or super-tax assessment, be allowed as a deduction: Provided that, as respects any assessment under the Income-tax Act, 1922 for any year beginning on or after the first day of April, 1958, the amount of business profits tax payable by any person under this Act shall not be allowed as a deduction in computing his total income for the purposes of the relevant income-tax or super-tax assessment. Provided further that where, under the provisions of this Act relating to deficiencies of profits relief is given by way of repayment from business profits tax chargeable for any chargeable accounting period previous to that in which the deficiency occurs, the amount of the deduction , if any, allowed shall not be altered, but the amount repayable shall be taken into account in computing the profits and gains of the business for the purposes of income-tax as if it were a profit of the business accruing in the previous year (as determined for that business for the purposes of the Income-tax Act, 1922) in which the deficiency of profits occurs.