Yes. A building control completion certificate is a required document for your VAT431NB claim, and it is what starts the 6-month submission window. The certificate is issued by your local authority building control team (or an Approved Inspector) after a final inspection confirms the works comply with Building Regulations. You need this document to submit a valid claim — and every day it is delayed reduces the time you have to prepare your invoice file.
The completion certificate date is Day 0 of your 6-month VAT431NB window. Apply for it promptly after works finish — delays in obtaining the certificate reduce the time you have to prepare and submit your claim.
A completion certificate from your local authority building control team, issued after a satisfactory final inspection confirming Building Regulations compliance, is the standard document HMRC requires.
If you used an Approved Inspector (private building control company) instead of the local authority, their final certificate serves the same purpose and is accepted by HMRC.
A sign-off from your structural engineer or architect (sometimes called a practical completion certificate) is not the same as a building control completion certificate. HMRC requires the building control document.
If building control raises issues (snags, missing certificates for services, outstanding works), the completion certificate may be delayed. Resolve these quickly — each day's delay reduces the time you have for your claim.
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 has a dedicated field for your completion certificate date. Once entered, it calculates and displays your VAT431NB submission deadline prominently — and marks your project as approaching completion so you can run a full pre-claim readiness check before the window closes.