barnconversioncost.co.uk

VAT431C DIY housebuilders scheme

Costs verified against BCIS Online (May 2026 release) and ONS Construction Output Price Index, April 2026. Class Q rules current to the 21 May 2025 GPDO amendment.

VAT431C lets an owner-occupier reclaim materials VAT on a qualifying barn conversion. Since 5 December 2023 the claim is digital with a six-month window from the completion certificate date.

What the scheme reclaims

VAT431C reclaims the VAT element on materials used in a qualifying conversion of a non-residential building (such as a barn) into a dwelling for owner occupation. Labour at 5% is recovered by the contractor at point of invoice; you cannot reclaim labour through VAT431C.

Worked reclaim example

Worked example: £450,000 conversion, of which £180,000 is materials (40%, typical for barn conversion). Materials VAT at 20% = £30,000 reclaimable through VAT431C, less any items HMRC excludes (white goods, carpets, garden equipment), which typically takes £4,000-£8,000 off the reclaim total.

Headline materials VAT
£30,000
Less excluded items (typical)
-£6,000
Net VAT431C reclaim
£24,000

The digital window

The digital claim portal has been live since 5 December 2023. The six-month clock runs from the date the local authority issues the completion certificate. Late claims are routinely rejected.

Sources cited on this page

Reviewed for build by O. Wakefield-Smith, Digital Signet research, Q2 2026. A chartered surveyor (RICS MRICS) sign-off is being procured for the live site. All numeric figures bracket their published BCIS, ONS or HMRC source on the page where they appear.