(1)For the purposes of this Chapter, there is a “normal rental excess” in relation to a lease for any period of account of the current lessor (“L”) throughout which the leasing arrangements fall for accounting purposes to be treated, in accordance with generally accepted accounting practice, as a finance lease or loan if—
(a)the normal rent for the period, exceeds
(b)the accountancy rental earnings for the period.
(2)The amount of the normal rental excess for that period is equal to that excess.
(3)But if the taxable rent for the period is reduced under section 908 (reduction of taxable rent by the cumulative accountancy rental excess), there is only a normal rental excess for the period if—
(a)the normal rent, reduced by an amount equal to the reduction under that section, exceeds
(b)the accountancy rental earnings.
(4)And in that case the amount of the normal rental excess for the period is equal to that excess.
(5)In this Chapter “cumulative normal rental excess”, in relation to the lease and a period of account of L, means so much of the total of the normal rental excesses for previous periods of account of L (as increased under section 914: recovery of bad debts following reduction under section 913) as has not been—
(a)set off under section 910 (reduction of taxable rent by the cumulative normal rental excess) against the taxable rent for any such previous period, or
(b)reduced under section 913 (relief for bad debts: reduction of cumulative normal rental excess).