4(1)Subject to the following provisions of this Part of this Schedule, Part I of Schedule 9 to the Finance Act 1972 shall not apply unless the land, caravan or house boat referred to therein either—
(a)is at the time the interest is paid used as the only or main residence of the person by whom it is paid (in this Part of this Schedule referred to as " the borrower") or of a dependent relative or former or separated spouse of his, or, if the interest is paid less than twelve months after the date on which the loan is made, is so used within twelve months after that date ; or
(b)is, in any period of fifty-two weeks comprising the time at which the interest is payable and falling wholly or partly within the year of assessment, let at a commercial rent for more than twenty-six weeks and, when not so let, either available for letting at such a rent or used as mentioned in paragraph (a) above or prevented from being so available or used by any works of construction or repair ;
and shall, in a case falling within paragraph (a) above, apply only within the limit imposed by paragraph 5 below.
(2)If it appears to the Board reasonable to do so, having regard to all the circumstances of a particular case, they may direct that in relation to that case sub-paragraph (1) above shall have effect as if for the references to twelve months there were substituted references to such longer period as meets the circumstances of that case.
(3)Where the land, caravan or house boat is used as the only or main residence of a dependent relative of the borrower it does not thereby fall within sub-paragraph (1)(a) above unless it is provided rent-free and without any other consideration.
(4)In this Part of this Schedule—
(a)" dependent relative " means, in relation to any person, a relative of his, or of his spouse, who is incapacitated by old age or infirmity from maintaining himself, or the mother of that person, or of his spouse, if the mother is widowed or living apart from her husband, or, in consequence or dissolution or annulment of marriage, a single woman; and
(b)" separated " means separated under an order of a court of competent jurisdiction or by deed of separation or in such circumstances that the separation is likely to be permanent.