FA97/Sch12/Para12(2) provides that on a part disposal only a
proportion of cumulative accountancy rental excess is to be
deducted. That proportion is to be arrived at by multiplying that
excess by the usual CG part disposal formula (' A ÷ (A + B)' -
see CG 12730 onwards). Thus if the unused excess is £1000, the
part disposal proceeds are £10,000 and the market value of the
part retained is £15,000 the excess which may be deducted is
£1000 x £10,000 ÷ (£10,000 + £15000) =
£400.
