SolvedCH14900 | Record Keeping: How long must records be retained for: Direct taxes claims not included in a return
From HM Revenue & Customs · Compliance Handbook
Records to support a claim not included in a return must be retained for a specified period. The person must retain their records until the later of
the date any enquiry into the claim or amended claim is completed, and
the day after the enquiry window closes. This is the later of
the first anniversary of the quarter day next following the date on which the claim was made,
the first anniversary of 31 January next following the year of assessment to which the claim relates, where the claim relates to a tax year,
the first anniversary of the end of the period to which the claim relates where the claim relates to a period other than a tax year.
We can charge a penalty if a person fails to keep or retain records, see SACM4020.