19Cash basis, etc.: relief for individuals
(1)If an individual born before 6th April 1917, or the personal representative of such an individual, is chargeable to tax under the last preceding section and—
(a)the individual was engaged in carrying on the trade, profession or vocation on 18th March 1968, and
(b)the profits or gains of the trade, profession or vocation were not computed by reference to earnings in the period in which the said 18th March fell, or in any subsequent period ending before or with the relevant date,
the net amount with which he is so chargeable to tax shall be reduced by multiplying that net amount by the fraction given below.
(2)Where subsection (2) of the last preceding section applies in relation to a change of basis taking place on a date before 19th March 1968, then in relation to tax chargeable by reference to that change of basis, that earlier date shall be substituted for the date in paragraph (a) above, and paragraph (b) above shall be omitted.
(3)The said fraction is—
(a)where on 5th April 1968 the individual had not attained the age of fifty-two, nineteen-twentieths,
(b)where on that date he had attained the age of fifty-two, but had not attained the age of fifty-three, eighteen-twentieths, and so on reducing the fraction by one-twentieth for each year he had attained, up to the age of sixty-four,
(c)where on that date he had attained the age of sixty-five or any greater age, five-twentieths.
(4)In this section—
" the net amount " with which a person is chargeable to tax under the last preceding section means the amount with which he is so chargeable after making any deduction authorised by Schedule 10 to this Act, but before giving any relief under this section,
" relevant date "—
(a)in relation to tax under subsection (1) of the last preceding section, means the date of the permanent discontinuance,
(b)in relation to tax under subsection (2) of that section, means the date of the change in basis.