Buying off-plan in London:
what if completion is delayed?
Buying off-plan means buying a home before it is finished; the CMA, the UK competition authority, notes that buyers will often purchase a new home before it is built or the estate is finished. This guide covers what to check in your contract if the date slips, how it affects your funding, and the protections that hold still.
Short answer
The completion date a developer gives you is an estimate; the New Homes Quality Code calls it the expected completion date and requires the developer to keep you updated. The date that gives you rights is in the contract: GOV.UK says a long-stop date can be written into it, letting you withdraw if there are long delays.
A delay also affects your funding: MoneyHelper says a full mortgage offer is usually valid for six months, and lenders are not obliged to extend it. If the developer becomes insolvent before completion, the deposit cover in the warranty policy may pay out.
The estimated date and the contract date are different
Under the New Homes Quality Code V2, the developer gives estimated completion dates in its marketing. Before you sign, it also gives you the expected completion date, its own estimate of when the home will be ready to move into, and must explain how and when it will update you on the timetable.
The NHQB buyer guide says the contract gives the expected date for the notice to complete and the anticipated date for legal completion. The Code expects the completion notice period to be usually at least 14 calendar days.
A long-stop date is not an estimate but a limit. GOV.UK’s “How to buy a home” says one can be written into your contract, letting you withdraw if there are long delays. The Code does not use the term, but requires the contract to say what happens if the home is not ready by the date given.
What to look for in the contract
Under Code V2, the contract of sale must set out clearly:
- When you can cancel, which might include an excessive or unreasonable delay in completing construction and sending the notice to complete.
- What happens if the home is not ready by the date the developer said.
- The completion notice period.
- How your deposit will be protected.
If the contract is cancelled, the developer must refund the contract deposit and any other amounts due to you within 28 days. The conditions of the right to cancel, how notice is given and the deadlines are in your contract; go through those clauses with your solicitor.
The CMA’s 2024 housebuilding market study reports finding instances of new homeowners suffering financial detriment where completions were substantially delayed by the developer.
For reservations made before 2 March 2026, the first version of the Code (V1) applies. If the developer follows the Consumer Code for Home Builders instead, that code’s rules apply; we cover both in our guide to snagging at handover.
How long a mortgage offer lasts
MoneyHelper says a full mortgage offer is usually valid for six months, and a mortgage in principle typically for 30 to 90 days. Another MoneyHelper article says offers typically last from six months to a year; the period that applies to you is in your offer document.
If completion runs past that, you can ask the lender for an extension. MoneyHelper says an extension may be between a month and six months, but lenders are not obliged to grant one and you may need to re-apply. GOV.UK also notes that a new-build mortgage offer may need to be refreshed if the date moves.
Plan the timing of your application around the estimated completion date. If you will borrow on income from Türkiye, our guide to a UK mortgage on Turkish income explains how lenders assess it.
If the developer becomes insolvent: deposit cover
The most serious delay is a developer that becomes insolvent before finishing. New home warranties can include cover for this period. NHBC Buildmark, for example, covers a lost deposit, or the reasonable extra cost of finishing the build, if the builder becomes insolvent between exchange and completion.
NHBC says this cover is typically 10% of the original purchase price, up to a maximum of £100,000, and is for the first owner only. Its 2026 product summary says the policy must be activated by you or your conveyancer. The cover depends on insolvency; if a solvent developer is late, your contract sets your rights.
Your home may have a different warranty provider; read the pre-completion cover in your own policy and contract.
Four things that are
not settled yet.
None of these is a scandal and none is hidden. They are the ordinary consequences of paying for something that does not exist yet, and each has a question that gets you a written answer.
The completion date is an estimate
Construction slips for reasons nobody in the transaction controls. The date you are given at reservation is an expectation, not a promise, and it can move by months. That is why our project pages give completion as the developer’s estimate, with the date we checked it; for example Streatham Common Junction.
What is the anticipated date, and separately, what is the backstop date in the contract after which I have rights?
The specification can move within limits
Materials, layouts and finishes may be altered. Most changes are minor and permitted by the contract; a significant one can give you a right to cancel. Compare the home types and floor areas on our project pages (for example The Lanes) with the specification in your contract.
What is fixed, what may change, and what counts as significant enough to give me an exit?
What surrounds you may not exist yet
In a phased development the view, the courtyard and the shops are often later phases. You are buying into a plan as much as a building. The area section of our project pages gives nearby plans from public records; for example Lightmakers.
What is consented next to this plot, what is under construction, and when does each phase land?
Your funding has to survive the wait
A mortgage offer is issued with a validity period, and a long build can outlast it. Currency can also move a long way between reservation and the completion payment. UK mortgage on Turkish income →
If completion is far out, when would an application realistically need to be made?
Five things that do not
depend on goodwill.
Off-plan is not a leap of faith. The protections are documentary, and each one is a specific thing you can ask to see before you pay anything.
Marketing still has to be accurate, because consumer protection law applies to what a developer tells you and contract terms must be fair.
But a render is not a specification, and the documents are the clearest thing you can hold someone to. The questions to put in writing →
It is not an automatic refund: the notice you must give, the timing and how the deposit comes back are all set by the contract, so go through that clause with your solicitor.
It is the single most important date in an off-plan contract and it is not the one in the brochure.
This is not a warning
against buying off-plan.
It would be easy to write this page as a list of dangers and finish by suggesting you buy something completed instead.
That would be misleading: the CMA notes that new homes are often bought this way, and buying early is how buyers get first choice of plot at a price fixed before the rest of the phase is released.
What we will not do is pretend the trade is free. You are accepting timing risk and specification risk in exchange for choice and a fixed price.
Whether that trade suits you depends on your horizon and how much certainty you need, which is a conversation rather than a rule.
Short questions,
short answers.
Is the completion date the same as the long-stop date?
No. The completion date is the developer’s estimate and can move. The long-stop date is in the contract, and once it passes the contract normally gives you a right to withdraw. The conditions are in your contract.
What if my mortgage offer expires before completion?
You can ask the lender for an extension; MoneyHelper says it may be one to six months, but lenders do not have to agree. If it is not granted, you may need to re-apply.
If I cancel because of a delay, do I get my deposit back?
Under the Code, if the contract is cancelled the developer refunds the contract deposit within 28 days. Whether you have a right to cancel is set by the delay and long-stop clauses in your contract.
What happens if the developer becomes insolvent?
A new home warranty may cover it. NHBC Buildmark, for example, covers a lost deposit if the builder becomes insolvent between exchange and completion, typically up to 10% of the price and a maximum of £100,000. Check the terms of your own policy.
When does the notice to complete arrive?
When the home is ready, the developer serves the notice to complete; the Code expects the notice period to be usually at least 14 calendar days. In that window you can check the home with a pre-completion inspection.
What this guide
is based on.
- GOV.UK: How to buy a home, section 6 (new build). Off-plan purchases, moving completion dates, refreshing the offer, the long-stop date. GOV.UK: Buying a home, transferring ownership. When the contract binds.
- NHQB: Code V2, part 2 and the Code V2 text (March 2026). Estimated and expected completion dates (1.2, 2.6), updates (2.8), delay and cancellation terms, notice period and deposit protection (2.7), refund within 28 days (2.13).
- NHQB: Your guide to buying a new build home. Notice to complete and the anticipated completion date.
- MoneyHelper: What happens when I get a mortgage in principle?, What can go wrong after a mortgage offer and How long do mortgage offers last? Validity and extensions.
- NHBC: Buildmark and the Buildmark product summary (2026). Insolvency cover before completion, 10% and £100,000, activation.
- CMA: Housebuilding market study, final report (February 2024) and supporting evidence. Off-plan purchases and delayed completions.
Last checked: 15 October 2026 (delays, mortgage offers and deposit cover); the rest of the page was last reviewed on 14 October 2026. This page is general information, not legal advice.
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and the phase plan.
We will tell you which of the four moving parts actually applies to that development, and what to ask before the reservation clock starts.
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