Overview
The builder's completion estimate has moved again. Your mortgage offer still carries the same expiry date. That mismatch needs dealing with before the house is finished, because the lender's promise to lend does not automatically move with the construction schedule.
The aim is to establish whether the existing offer can support the revised completion date, whether more underwriting is needed, and what your purchase contract commits you to. Your broker and solicitor need the same information early enough to act.
Quick Answer (Read This First)
Yes, a mortgage offer can expire while a new build is delayed. An extension is lender-specific and is not guaranteed. Ask your broker or lender to confirm the exact expiry date, the current new-build policy and the latest point at which any extension request can be made.
Tell your solicitor at the same time. If you have exchanged contracts, or concluded missives in Scotland, the expiry of your mortgage offer does not automatically release you from the purchase contract.
IMPORTANT
If the offer will expire before the expected completion date and you are already contractually committed, contact your solicitor and broker urgently. Do not agree a new completion date on the assumption that the lender will extend.
Put the Different Dates Side by Side
“Ready in October” is not precise enough for a lender working to a fixed deadline. Ask the builder for its revised estimate in writing and explain that you need it to manage mortgage funding.
| Date or condition | Who confirms it? | Why it matters |
|---|---|---|
| Mortgage offer expiry | Lender or broker | Establishes the funding deadline and any conditions |
| Expected build completion | Builder | Shows whether the project fits inside the offer period |
| Contractual completion process | Solicitor | Explains when you can be required to complete |
| Any contractual long-stop date | Solicitor | Establishes what rights arise if building runs too late |
| Funds-request and legal-document deadlines | Solicitor and lender | Completion needs preparation before the final day |
An agreement in principle is not the formal offer. Nor is the end date of your chosen fixed-rate product necessarily the date by which the purchase must complete. Our mortgage process timeline explains the stages.
There Is No Universal New-Build Extension
Do not rely on a general claim that every offer lasts six months and can then be extended for another six. Lenders can give new builds a longer initial offer, a limited extension, a conditional grace period or a requirement to submit a fresh application.
For example, on 13 September 2026, Nationwide's intermediary criteria list 270-day new-build offers and say a new-build offer extension cannot be requested. A 15-day grace period can apply if the Certificate of Title reaches it before the original offer expires.
That is one lender's dated policy, not a rule for other lenders or a guarantee for a particular case. It also shows why an old article promising a routine extension can lead you in the wrong direction. Ask the adviser handling your application to check the current policy against your actual offer.
What an Extension or Replacement Application May Involve
Ask whether the lender will retain the original product and rate, whether the mortgage amount can stay the same, and whether it needs updated evidence. Depending on the route and circumstances, that can include fresh income documents, bank statements, credit checks or an updated valuation.
Prepare the documents before being asked repeatedly. If a payslip or account statement will be issued shortly, tell the adviser when it will be available. Report material changes to employment, income, borrowing or the purchase rather than assuming the original checks settle the matter permanently.
A fresh application may be assessed using current criteria and products. Being approved once does not guarantee the same borrowing amount or rate later. See what can cause a mortgage offer to be withdrawn for the separate issue of an offer being pulled before expiry.
If You Have Not Yet Committed to the Purchase
Ask your solicitor how the proposed contract deals with delay before exchanging or signing anything that commits you. Discuss the build estimate, offer expiry, any long-stop provision and what happens if mortgage funding becomes unavailable.
A reservation deadline or sales-office reassurance is not the same as legal protection. Put the funding problem to the solicitor explicitly: “If the lender will not extend, what does this contract let me do, and what could I lose?”
In England and Wales, exchange creates the binding purchase contract described in GOV.UK's conveyancing guidance. Scotland uses missives; mygov.scot explains the binding-contract stage. Northern Ireland has its own conveyancing practice, so obtain advice on the particular contract and jurisdiction.
If You Have Already Exchanged or Concluded Missives
Get legal advice immediately if funding and completion no longer line up. The consequences depend on the contract and facts; loss of a deposit or further liability may be possible if you cannot complete when required.
Ask your solicitor to establish whether the builder's revised timetable triggers any contractual right, whether a variation is possible, and how any notice to complete must be handled. A long-stop date is not automatically the same as the mortgage expiry date, and its wording matters.
Keep the financing and legal work moving together. An extension request without a credible revised build date may be difficult to assess. A revised completion commitment without confirmed mortgage funding can create a different problem.
Compare the Cost of the Available Options
If the current lender cannot accommodate the delay, your broker can investigate alternatives. Ask for the likely new rate, fees, monthly payment and time needed for underwriting and valuation. Include any unrecoverable fees from the first application in your comparison.
Also budget for practical delay costs: extra rent, storage, removals changes and the possibility of overlapping housing costs. Use actual quotations where available. The cheapest mortgage product on paper may not be workable if it cannot be offered and completed in time.
Do not fill a mortgage funding gap with a loan or bridging arrangement without specialist advice and the required disclosures. New borrowing can affect affordability and may create a further obstacle to the eventual mortgage. Our guide to comparing mortgage deals by their true cost can help you identify costs to ask about.
A Practical Update to Send Your Broker
Put the case reference, property address, offer expiry and revised build estimate in the same message. Attach the builder's written update and state whether you have already exchanged or concluded missives.
Ask the broker to confirm the available route, documents needed, earliest application date and final deadline. Ask for written confirmation when any extension or replacement offer is approved; a request being submitted is not the same as funding being agreed.
Keep the solicitor copied into the resulting dates through your normal communication process. If the build slips again, repeat the check rather than assuming the first extension covers it.
Frequently Asked Questions
Browse the mortgage guides for related questions. This is general UK information, not personalised mortgage or legal advice. Your home may be repossessed if you do not keep up repayments on your mortgage. Sources checked on 13 September 2026.
