Inputs
- Single dwelling: 180 sqm = 1,938 sqft GIA.
- NIA: 95 percent (1,841 sqft saleable).
- GDV: 1,841 sqft x £340/sqft = £625,940. Round 625k.
- Build: 180 sqm x £2,200/sqm = £396,000. Less VAT reclaim ~30,000 = 366,000 net.
Residual ledger
GDV | £625,940 |
Build cost (gross) | (£396,000) |
Less VAT reclaim on materials (post-completion)(DIY housebuilders scheme) | £30,000 |
Net build cost | (£366,000) |
Professional fees (8%) | (£29,280) |
s106 / CIL / BNG (self-build relief, single plot) | £0 |
Contingency (10%) | (£39,528) |
Finance interest (9.75%, 14 months, 50% avg) | (£24,733) |
Subtotal costs | (£459,541) |
Target profit (15% PoC) | (£68,931) |
Residual before SDLT gross-up | £97,468 |
Plot SDLT non-residential at 5% gross-up | |
Max plot bid | £92,827 |
| Verdict | APPROVED (typical plot price in rural PL postcodes 80 to 150k) |
VAT mechanics
HMRC VAT431NB DIY housebuilders reclaim recovers 20 percent VAT on materials. Labour from a VAT-registered builder is zero-rated; do not reclaim. Submit via the HMRC online portal within 6 months of completion. Indicative recovery on a 180 sqm self-build at mid spec: £25,000 to £35,000.
Cornwall caveat
Cornwall's second-home council tax premium (200 percent from 1 Apr 2025) hits resale velocity in PL postcodes. Apply a 3 to 6 month sales-period extension if the build is for sale rather than owner-occupation; finance interest roll-up rises accordingly.