Converting 2 flats into 1 - how to claim VAT?

[clareanna]

Hi all,
we’re converting 2 flats into one family home. My husband is doing the work himself, so would qualify as a DIY builder. I can’t work out if or how we could claim back VAT? I think we are eligible to pay a reduced rate of 5% on building materials and services?

All help gratefully received! I’ve tried phoning HMRC but was on hold for ages...