Four years of VAT you may still be able to correct
There is a widespread assumption that once a VAT return is filed and the quarter is behind you, the numbers are settled. For most errors, they are not.
The general time limit for correcting VAT errors is four years from the due date of the return in question. Within that window, an error can usually be adjusted, either on a later return or by notifying HMRC directly, depending on the size of the correction and how it arose.
The reason this matters is that VAT errors are rarely dramatic. They are small, repeated and quiet: a rate applied to the wrong line, a partial exemption calculation that stopped reflecting the business two years ago, a supply treated as standard-rated that was not.
Bad debt relief is the clearest example. If you accounted for VAT on an invoice and the customer never paid, you can generally reclaim that VAT once the debt is at least six months overdue and has been written off in your accounts. The claim itself must be made within four years and six months of the later of the payment due date and the date of supply.
Very few businesses run that check as a matter of routine. The write-off happens in the ledger, the commercial loss is absorbed, and the VAT sits with HMRC rather than coming back.
Energy is another. Businesses using a low volume of energy, and certain qualifying premises, may be entitled to the reduced 5% VAT rate rather than 20%. Where the supplier has been billing at the standard rate throughout, the difference is generally recoverable, and the rate can be corrected going forward as well.
In each case, the work is procedural rather than clever. Somebody has to go back, read the returns, and check them against what the business actually did. That is the part that never gets scheduled.
