3(1)For the purposes of computing the amount of profile or gains in respect of which Class 4 contributions are payable, relief shall be available under, and in the manner provided by, the following provisions of the Act of 1970, that is to say—
(a)section 168 (set-off of trade losses against general income), but only where loss arises from activities the profits or gains of which would be brought into computation for the purposes of Class 4 contributions ;
(b)section 169 (extension of right of set-off to capital allowances);
(c)section 171 (carry-forward of loss against subsequent profits);
(d)section 174 (carry-back of terminal losses).
(2)The following relief provisions shall not apply, that is to say—
(a)Chapter H of Part I of the Act of 1970 (personal reliefs);
(b)sections 226 and 227 of that Act (premiums or other consideration under annuity contracts and trust schemes);
(c)section 75 of the [1972 c. 41.] Finance Act 1972 (relief for payment of interest);
(d)section 173 of the Act of 1970 (carry-forward as losses of amounts to be taxed under section 53) ; and
(e)section 175 of that Act (treatment of interest as a loss for purposes of carry-forward or carry-back).
(3)Where in a year beginning on or after 6th April 1975 for which a person claims and is allowed relief by virtue of sub-paragraph (1) above there falls to be made in computing his total income for income tax purposes, or that of a person's wife or, as the case may be, a person's husband, a deduction in respect of any loss, and the deduction or part of it falls to be so made from income other than profits or gains of a trade, profession or vocation, the amount of the deduction made from the other income shall be treated as reducing the person's profits or gains (that is to say the profits or gains of any relevant tirade, profession or vocation as computed for the purpose of the charge to Class 4 contributions) for subsequent years (being deducted as far as may be from those of the immediately following year, whether or not he claims or is entitled to claim relief under this paragraph for that year, and, so far as it cannot be so deducted, then from those of the next year, and so on).
(4)Relief shall be allowed, in respect of—
(a)payments under section 52 or 53 of the Act of 1970 (annuities and other annual payments, etc.); or
(b)payments under section 75 of the Finance Act 1972 (relief for payment of interest), being payments for which relief from income tax is or can be given,
so far as incurred wholly or exclusively for the purposes of any relevant trade, profession or vocation, by way of deduction from or set-off against profits or gains chargeable to Class 4 contributions for the year in which the payments are made; and, in the case of any insufficiency of the profits or gains of that year, the payments shall be carried forward and deducted from, or set off against, the profits or gains of any subsequent year Obeing deducted or set off as far as may bo from or against the profits or gains of the immediately following year, whether or not relief can be claimed under this paragraph for that year, and so far as it cannot be so deducted, from or against those of the next year, and so on).