(1)In section 259 of the Taxes Act 1988 (additional relief in respect of children), in subsection (2), for the words “and (4)” there shall be substituted the words “to (4A)”; and after subsection (4) there shall be inserted—
“(4A)Where—
(a)a man and a woman who are not married to each other live together as husband and wife for the whole or any part of a year of assessment, and
(b)apart from this subsection each of them would on making a claim be entitled to a deduction under subsection (2) above,
neither of them shall be entitled to such a deduction except in respect of the youngest of the children concerned (that is to say, the children in respect of whom either would otherwise be entitled to a deduction).”
(2)This section shall apply for the year 1989-90 and subsequent years of assessment.