SolvedCH14700 | Record Keeping: How long must records be retained for: PAYE and Construction Industry Scheme
From HM Revenue & Customs · Compliance Handbook
If the person is an employer or makes payments within the Construction Industry Scheme, they must retain their PAYE and/or Construction Industry Scheme records for 3 years after the end of the tax year to which they relate.
To the extent that these records are required to make a correct and complete return of business profits, the records must be kept for the period described in CH14530 (income tax) or CH14600 (corporation tax).
More information is in the Employer Compliance section of the Compliance Operational Guidance (COG) at COG900200+ or the Construction Industry Scheme Reform Manual (CISR).