Section 783AM | Election for partial relief
From legislation.gov.uk
(1)An individual may elect for partial relief to be given for a tax year if the individual's relevant income for the tax year exceeds the individual's trading allowance for the tax year (see sections 783AI and 783AJ).
(2)An election must be made on or before the first anniversary of the normal self-assessment filing date for the tax year for which the election is made.