Late claims for input tax: Quantification of a claim: What amendments cannot be introduced into an open claim
Essentially, if the amendment that the claimant is trying to make would normally constitute a claim for overdeclared output tax under Section 80 of the VAT Act 1994, it cannot be treated as an adjustment to a claim under Regulation 29 of the VAT Regulations 1995.
For example, Alpha Ltd makes a claim on 30 June 2012 for unclaimed input tax that was incurred in the accounting period ending on 30 September 2008. On 12 July, they discover that they have overdeclared their output tax liability in that same period.
They cannot treat that as an adjustment to his Regulation 29 claim but they are still in time to make a claim under Section 80 in any event. That’s because they can make such a claim at any time within four years from the end of the accounting period in which the output tax was overdeclared - in this scenario, 30 of September 2008.
If, on the other hand, they only discover the overdeclaration on 5 of October 2012, they are out-of-time to make the claim - see the section in this guidance on making claims under section 80 for further information.
If a trader discovers other input tax errors that are unrelated to the open claim (the one made on 30 June 2012), they will be the subject of a new claim and cannot be treated as amendments to that earlier claim.