Yes. A building control completion certificate is a required document for your VAT431C claim and it is what starts the 6-month submission deadline. 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 cannot submit a valid VAT431C claim before a completion certificate has been issued.
The completion certificate date is Day 0 of your 6-month VAT431C 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, 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, outstanding works, missing certificates for services) the completion certificate may be delayed. Resolve these issues quickly — each delay reduces the time you have to prepare 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 VAT431C submission deadline prominently — and marks your project as approaching completion so you can run a full pre-claim readiness check before the window closes.