VATREC3021 - Preserving records: Determining the 6 year period - Documents which record individual events
Records such as VAT invoices, should be preserved for 6 years from the date of issue. This rule applies equally to documents that refer to events that are to take place in the future (possibly a future date of payment or future supply of goods). In such cases the 6-year period runs from the date on which the document itself is issued and not from the date of the future event.