The Water Reorganisation (Capital Allowances) Order 1989
Section 2(3) of the Capital Allowances Act 1968 provides for the calculation of the writing-down allowance in respect of a period which ends after the sale of the relevant interest in an industrial building or structure by reference to the residue of certain expenditure. The writing-down allowance for a chargeable period is the residue reduced in the proportion which the length of the chargeable period bears to the unexpired part, at the date of sale, of the period of 25 or, in certain cases, 50 years beginning with the date on which the building or structure was first used.