Industry & PartnersMortgage BrokersSelf-Build Mortgage Clients: The £15,000–£30,000 VAT Reclaim Most Brokers Never Mention
Clients building a new home are usually eligible for HMRC's VAT431NB DIY Housebuilders reclaim — typically worth £15,000–£30,000 or more. Qualifying contractor construction services should be zero-rated (0% VAT) at source, and VAT on materials the client buys directly is reclaimed after completion. The strength of that claim depends entirely on the invoices and evidence the client keeps from day one — which is why the best time to introduce VATBuild is at offer stage, before procurement begins.
That is the typical value of a self-build VAT431NB reclaim — money your client is entitled to, but only if they have the right invoices, the right evidence and the right VAT treatment throughout the build. HMRC allows one claim per project, submitted within 6 months of the completion certificate, with no second chance. A contractor who charges 20% on services that should have been 0% creates an overcharge that cannot be added to the claim — it must be corrected by the supplier.
Qualifying construction services on a new dwelling should be zero-rated by the contractor at the point of invoicing. There is no VAT to reclaim on these — it should simply not be charged in the first place.
Materials the client buys directly from merchants are correctly charged at 20% and are reclaimable via VAT431NB after completion, provided they are incorporated into the building and supported by valid VAT invoices.
If a contractor charges 20% on services that qualify for zero-rating, the excess cannot be added to the VAT431NB claim. The client needs a corrected invoice from the contractor — far easier to obtain while the build is still underway.
At offer stage the client has not yet procured contractors or paid invoices, so VAT planning can start from the beginning. VATBuild is still useful mid-build (catching up on invoice organisation) and pre-completion (checking the reclaim position before submission).
VATBuild maps the client's project to the correct HMRC VAT treatment before a single invoice is uploaded, checks each contractor invoice for zero-rating errors, separates reclaimable material purchases from excluded items, tracks the 6-month VAT431NB deadline, and prepares a structured, evidence-backed claim summary. Your client arrives at completion with their VAT position under control — and your name stays associated with a valuable outcome.