The correct thing to do would be to file supplementary returns for each period dividing up the VAT claims into the relevant periods. However, in practice I have encountered the following other scenarios :-
- File all on a supplementary return for the period which ends the accounting year. So if Year is Jan-Dec then file a supplemenary for whatever VAT period ends 31/12.
- Claim the credit on the next available VAT return being filed which might have the effect of reducing what otherwise would be a payment. In that case, as the period is possibly after the year end, it would need to be clear when doing up the accounts that this is a debtor at year end.