s 324 Net allowances
For the purposes of this Chapter, the amount of the net allowances made, in relation to any qualifying expenditure, is— where— I is the amount of any initial allowances made to the person in relation to that qualifying expenditure, WDA is the amount of any writing-down allowances made to the person for chargeable periods ending on or before the date of the balancing event giving rise to the balancing adjustment, RDA is the amount of any allowances under Part 6 (research and development allowances) made to the person for such chargeable periods, and B is the amount of any balancing charges made on the person for such chargeable periods.