Section 816 | Further provision about elections under section 815
From legislation.gov.uk
(1)An election under section 815 must specify the expenditure to which it relates.
(2)The election must be made not more than 2 years after the end of the accounting period in which the expenditure was incurred.
(3)The election must be made in writing to an officer of Revenue and Customs.
(4)The election is irrevocable.