Pillar Guide · Updated July 2026
Buying Off-Plan New Build Property: A Complete UK Guide for 2026/27
Buying a property before it is finished — off-plan — can come with developer incentives and the appeal of a brand-new home, but it also carries specific risks around mortgage timing, build delays and warranty cover that do not apply to buying an existing property.
What Buying Off-Plan Means
Buying off-plan means agreeing to purchase a new build home before it is complete, sometimes before construction has even begun, based on floor plans, computer-generated images, a show home, and a specification list provided by the developer. It differs from buying an existing property, where you can see and inspect the finished home before committing.
Reservation Fees
A reservation fee secures a specific plot for you while you arrange your mortgage and instruct solicitors, and is usually deducted from the purchase price on completion. Check the reservation agreement carefully, since the fee may not be refundable if you withdraw from the purchase, and there is usually a set period within which you must exchange contracts.
Mortgage Offer Expiry Risk
Mortgage offers are typically valid for only a limited number of months, but off-plan builds can take significantly longer to complete than originally planned, meaning your mortgage offer can expire before the property is ready. Ask your lender or broker about extension options, and consider the possibility of needing to reapply — potentially at a different interest rate — if completion is delayed.
Build Delays
Construction delays are common with off-plan developments, and many developer contracts specify a range of possible completion dates rather than one fixed date, sometimes with a longstop date after which either party can withdraw. Build in financial flexibility for possible delays, including rental costs if you need to extend your current living arrangements.
New Build Warranties
New build homes typically come with a structural warranty from a provider such as NHBC or a similar body, usually covering an initial defects period of around two years and structural issues for a longer period, often around ten years in total. Check exactly what is and is not covered, and keep all warranty documentation safe after completion.
Developer Incentives
Developers sometimes offer incentives such as contributions towards Stamp Duty or legal fees, part-exchange of your existing property, deposit-contribution schemes, or upgraded fixtures and fittings. Always weigh the value of any incentive against the underlying asking price, since incentives are sometimes reflected in a higher headline price than an equivalent existing property nearby.
Snagging Inspections
A snagging inspection checks for defects, unfinished work and quality issues in a newly built home, and is strongly recommended before or shortly after legal completion, even though the property is new and covered by a warranty. Many buyers commission an independent snagging surveyor rather than relying solely on the developer's own final checks.
Exchange and Completion
With off-plan purchases, exchange of contracts often happens well before completion, since completion is tied to the building work finishing rather than a calendar date agreed directly with a seller. Stamp Duty Land Tax is generally due based on the rates and reliefs in force at legal completion, so check current rates before budgeting, since they can change between reservation and completion.