You must submit your VAT431NB claim to HMRC within 6 months of the relevant completion date. The clock starts when your building control completion certificate is issued — not when you move in and not when construction work stops. Missing the window means your claim is permanently lost. HMRC has no discretion to accept late VAT431NB claims.
The VAT431NB deadline is absolute. There is no appeal process, no hardship exception, and no HMRC discretion once the window closes. A claim worth £20,000 in reclaimable VAT becomes £0 if submitted one day late.
The 6-month window begins on the date your local authority building control inspector issues a completion certificate (or equivalent final certificate from an Approved Inspector). This is the trigger date — not practical completion or moving in.
A practical completion certificate from your contractor is not the VAT431NB deadline trigger. The building control completion certificate is what starts the clock.
Moving into the property does not start the 6-month window. However, if you occupy before the completion certificate is issued, apply for it promptly — any delay reduces your preparation time.
HMRC does not accept VAT431NB claims submitted after the 6-month deadline. There is no discretion, no appeal route, and no alternative mechanism. The deadline is fixed.
VATBuild is not affiliated with HMRC. References to HMRC publications are for informational purposes. Always consult a qualified tax adviser before submitting a reclaim.
VATBuild tracks your project's completion status and calculates your VAT431NB submission deadline once a completion certificate date is entered. It displays the deadline prominently and surfaces all outstanding issues — missing invoices, supplier corrections, evidence gaps — so you can act before the window closes.