Averaging: claims: time limit
S222(5) Income Tax (Trading and Other Income) Act 2005
A claim for averaging must be made before the end of the first anniversary of 31 January following the year of claim. So a claim for averaging in 2016/2017 must be made by 31 January 2019.
See, however, BIM84150 regarding certain adjustments to assessments for earlier years and where a late claim is made in an enquiry case.
Withdrawal of claims may be allowed within the normal time limit.