Self-Build Mortgages in 2027
Staged drawdown, plot purchase, planning, warranties, VAT and CIL, and how to keep a self-build on budget.
- What a self-build mortgage is and who it suits
- How staged drawdown works
- Buying the plot and planning permission
- How lenders assess a self-build
- Building regulations, warranties and insurance
- Choosing a build route and managing risk
- Valuation, living arrangements and finishing the loan
- Tax and levy points: CIL and VAT
- Costs, contingency and timeline
- Tips and tricks, common mistakes and a checklist
- How OMB can support you
The short version
A self-build mortgage funds land and construction in stages as the build progresses, so it works very differently from a normal purchase. This guide covers how stage payments work, what lenders want to see, the planning and tax points to check, and how to protect your budget.
- Funds are released in stages after surveyor inspections, either in arrears (after the work) or in advance (before the work).
- Lenders usually need planning permission, building regulations approval, detailed costings and a warranty or architect's certificates.
- A contingency of at least 10 to 15% of build costs is a sensible minimum, because lenders do not usually increase the loan if costs rise.
- Self-builders may be able to claim an exemption from the Community Infrastructure Levy, but it must be applied for before work starts.
- DIY housebuilders may reclaim VAT on eligible materials from HMRC, and the claim must be made within six months of completion.
Talk to a broker before buying the plot
lender criteria can rule out a plot or a build route, and finding out afterwards is expensive.
What the full guide covers
- What a self-build mortgage is and who it suits
- How staged drawdown works
- Buying the plot and planning permission
- How lenders assess a self-build
- Building regulations, warranties and insurance
- Choosing a build route and managing risk
- Valuation, living arrangements and finishing the loan
- Tax and levy points: CIL and VAT
- Costs, contingency and timeline
- Tips and tricks (8), common mistakes (6) and a 12 point checklist
- How OMB can support you, with a fictional worked example
Illustrative example: building on a plot already owned
Sam and Priya already own a plot with full planning permission and plan to build a family home using a main contractor on a fixed price. After reviewing the costings and the contractor's payment schedule, we compare lenders offering stage payments in arrears and in advance. They choose a lender whose stages fit the contractor's invoices, set aside a contingency of 12% of the build cost and apply for a CIL exemption before work starts. Once the home is complete they move to a standard repayment mortgage. This is an illustrative example only, not a real client, and every case is different.
Names, figures and circumstances are fictional and illustrative only. They do not represent an actual client of Our Mortgage Broker Limited.
Self-Build Mortgages in 2027
Staged drawdown, plot purchase, planning, warranties, VAT and CIL, and how to keep a self-build on budget.
Want to talk it through?
Self-build lending is specialist, and criteria differ widely. Our CeMAP-qualified advisers are whole of market and can find lenders whose stage payment structure fits your project and budget.
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Your home may be repossessed if you do not keep up repayments on your mortgage. Most buy-to-let and commercial mortgages are not regulated by the Financial Conduct Authority. Our Mortgage Broker Limited is authorised and regulated by the Financial Conduct Authority (FRN 944663). Registered in England and Wales, company no. 11358646. Registered office: 23 Berkeley Square, Mayfair, London W1J 6HE. There may be a fee for mortgage advice: we may charge up to 1% of the loan amount, and our typical fee is £500. Your fee agreement sets out the exact fee and when it is payable (at decision in principle, application or mortgage offer); fees are not refundable once due. We usually also receive commission from the lender. Protection and insurance products are subject to underwriting and the policy terms and conditions. This guide is general information only and is not personal advice. Case studies are fictional, illustrative examples and do not represent real clients. Rates, tax and regulatory information are correct as at October 2026 and may change, including at the Autumn Budget on 28 October 2026.