s 372 Entitlement to writing-down allowance
(1) A person is entitled to a writing-down allowance for a chargeable period if— (a) qualifying expenditure has been incurred, (b) at any time during that chargeable period he is entitled to the relevant interest in relation to the qualifying expenditure, and (c) that time falls within the writing-down period. (2) The writing-down period, in relation to qualifying expenditure incurred by a person, is 25 years beginning with the first day of the chargeable period of that person in which the qualifying expenditure was incurred. (3) A person claiming a writing-down allowance may require the allowance to be reduced to a specified amount.