Where the value of a person's estate was increased by a chargeable transfer ("the first transfer") made not more than five years before—
the tax chargeable on the value transferred by the transfer made on his death or, as the case may be, referred to in paragraph (b) above ("the later transfer") shall be reduced by an amount calculated in accordance with subsection (3) below.
The conditions referred to in subsection (1)(b) above are—
The amount referred to in subsection (1) above is a percentage of the tax charged on so much of the value transferred by the first transfer as is attributable to the increase mentioned in that subsection; and the percentage is—
Where in relation to the first transfer there is more than one later transfer, the reduction provided for by this section shall be given only in respect of the earliest of them, unless the reduction represents less than the whole of the tax charged as mentioned in subsection (3) above; and in that case a reduction may be made in respect of subsequent transfers (in chronological order) until reductions representing the whole of that tax have been made.
For the purposes of subsection (4) above, a reduction made in accordance with paragraph (a) of subsection (3) above represents an equivalent amount of tax, a reduction made in accordance with paragraph (b) represents the amount of tax of which it is 80 per cent., and so on.
In determining for the purposes of this section whether or to what extent the value of the transferor's estate was increased by a chargeable transfer, there shall be disregarded any excluded property consisting of a reversionary interest to which he became entitled on the occasion of or before the chargeable transfer.
Where—
this section shall apply as if the increase had been by the chargeable transfer made on the occasion of the death.