TL;DR: A residential mortgage offer in the UK is typically valid for 3 to 6 months from the date it is issued, with the most common length being 6 months for purchase mortgages and 3 to 4 months for remortgages. The exact length is set by the lender and is stated on the offer letter. New-build mortgage offers are often extended to 6 to 9 months (sometimes longer) to accommodate construction delays. If completion has not happened before the offer expiry date, the offer lapses and the lender must reassess affordability and rates before reissuing or extending. Most lenders will consider a short extension if the application has not changed and the new rates are accepted.
Last reviewed May 2026
For a buyer in a property chain, the mortgage offer is one of the few documents whose validity period is fixed and largely outside the buyer's control. The chain has to complete before the offer expires, or the buyer faces the cost and risk of reapplying. Knowing exactly how long an offer lasts, and what happens if it runs out, is essential to managing the timetable.
This guide sets out the typical offer durations across UK lenders, the rules on extending an offer, the special positions on new-build purchases, what happens if rates rise or fall during the offer period, and the practical steps a buyer should take if completion looks like it may slip past the expiry date.
How long a standard residential mortgage offer lasts
A residential mortgage offer is the formal commitment from the lender to lend on the terms set out in the offer letter, subject to completion of the legal work and any conditions stated on the offer. UK lenders set their own offer validity periods. The most common durations are 3 months and 6 months, although a few lenders use 4 months, and some products have longer offer periods.
For a purchase mortgage, the typical offer is valid for 6 months from issue. This is intended to cover a normal conveyancing timetable in England and Wales: searches, enquiries, exchange, and completion, with some buffer for chain delays. A handful of lenders offer 90-day or 4-month offers, particularly on certain fixed-rate products or for specialist applications.
For a remortgage (refinancing an existing property with no purchase involved) the offer is more often 3 to 4 months, on the basis that the legal work on a remortgage is faster than on a purchase and a longer offer would simply expose the lender to interest-rate risk. Some lenders run remortgages on 90-day offers.
The offer letter itself states the expiry date in plain terms. The first thing a borrower should do on receiving the offer is note the expiry date and check the broker or solicitor is aware of it.
How long a new-build offer lasts
New-build purchases routinely involve longer offer periods because construction can be delayed. Most large UK lenders offer 6-month offers as the headline, extendable to 9 or even 12 months in some cases for new-build applications, sometimes with a re-valuation requirement at the 6-month mark.
The construction phase risk falls into two categories. Off-plan purchases (where the property is bought from the developer before it is built) have the longest exposure and need the longest offer validity. Standing new-builds (already constructed and ready to occupy) have shorter exposure and use the standard 6-month offer in most cases.
Lenders typically attach conditions to long-validity new-build offers, including the right to revalue the property if completion slips beyond a certain point, the right to reassess affordability if the borrower's circumstances change, and the right to withdraw if the borrower's credit position deteriorates.
What happens if the offer expires before completion
If the buyer has not completed by the offer expiry date, the offer lapses. The lender's commitment ends. There is no automatic renewal. The buyer cannot complete the purchase using the lapsed offer; the solicitor cannot draw down funds against it.
The buyer has three options: apply for an extension, reapply for a new mortgage with the same lender, or apply with a different lender. Extension is the cheapest and quickest where the lender allows it. Reapplication is required where the lender will not extend, where the buyer's circumstances have changed, or where the buyer wants to switch products.
A reapplication is treated as a fresh application: new affordability check, new credit check, new valuation (often), new rate. If interest rates have risen since the original offer, the new rate may be materially worse than the lapsed offer. If rates have fallen, the new rate may be better, but the borrower has to weigh that against the cost and delay of reapplying.
How extensions work
Most lenders will consider a short extension to a mortgage offer if the underlying application has not changed materially and the delay is genuine (chain hold-up, builder delay, conveyancing issue rather than borrower circumstance). The extension is usually granted in writing for an extra 1 to 3 months and is at the lender's discretion.
Some lenders require a re-validated affordability assessment for an extension, which means resubmitting recent payslips, bank statements, and credit checks. The lender's underwriter reviews the updated information and decides whether to extend on the original rate or to require a re-rate to current market pricing.
The product rate during an extension can go either way. On a long fixed-rate offer where market rates have moved against the borrower, the lender may insist the extension is on the new (higher) rate. On a short extension where rates are stable, the original rate often continues. The extension letter sets out the terms.
Where the application has changed materially (loss of employment, change of property, addition of a new applicant, change in deposit source) the lender will usually treat it as a new application rather than an extension.
What if interest rates change while the offer is live
A standard mortgage offer locks the product rate at the figure stated on the offer for the validity period. If market rates rise during the offer period, the borrower keeps the lower rate stated on the offer. If market rates fall, the borrower is still bound to the offer rate unless they reapply for a new product.
Many lenders operate a "rate switch before completion" facility allowing the borrower to switch to a lower rate from the same lender before completion without losing their place in the conveyancing queue. Some lenders allow this freely; others restrict it to a window before completion or charge a small fee. The broker can confirm the lender's policy.
If rates fall materially and the lender will not switch, the borrower can theoretically withdraw and reapply, but this resets the legal work timeline (some elements such as the valuation may have to be redone) and risks losing the property if the chain is moving. The decision depends on the size of the rate fall.
Practical steps if the offer is about to expire
The first step is to contact the broker or lender at least 3 to 4 weeks before the expiry date. Most lenders take 5 to 10 working days to process an extension request, and the buyer wants the extension confirmed before the offer lapses (not after).
The second step is to identify the genuine cause of the delay, in writing if possible. A chain hold-up letter from the conveyancer, a builder's delay confirmation, or a search-result delay note all help the lender's underwriter assess whether the extension is reasonable. Lenders are more willing to extend where the cause is identifiable.
The third step is to keep the credit position clean and the affordability stable during the extension request. A new credit search may be performed; new debts taken on during the offer period (a new credit card, a large hire purchase) can lead to a refused extension or a new affordability assessment.
The fourth step is to have a fallback. If the extension is refused, the broker should be prepared to submit a fresh application either to the same lender or a different one quickly enough to keep the chain moving. Some brokers will run a parallel application as a contingency where chain risk is high.
How we verified this
The duration ranges and extension rules described here are taken from the published policies of UK Finance member lenders, the Financial Conduct Authority's MCOB sourcebook on residential mortgages (in particular the rules on responsible lending and the duration of binding offers), and MoneyHelper's published guidance on the mortgage process. No specific lender's product validity, FRN, or extension fee has been invented; the ranges reflect typical market practice across major UK lenders.
Disclaimer: This article is general information about UK residential mortgage offer validity. It is not financial advice. Specific offer terms and extension policies vary by lender and product. Anyone in a live mortgage application should rely on the wording of their own mortgage offer and the lender's confirmation rather than on general guidance.
Frequently asked questions
How long does a mortgage offer last in the UK?
Most residential purchase mortgage offers in the UK are valid for 6 months from the date of issue. Some lenders use 3 or 4 months. Remortgage offers are typically shorter at 3 to 4 months. New-build offers are often extended to 6 to 9 months to accommodate construction delays. The expiry date is stated clearly on the offer letter.
Can a mortgage offer be extended?
Yes, most lenders will consider a short extension of 1 to 3 months where the underlying application has not changed materially and the delay is genuine (chain hold-up, conveyancing issue, builder delay). The borrower normally has to request the extension before the offer expires, and the lender may require updated affordability information. Whether the original product rate continues during the extension depends on the lender.
What happens if my mortgage offer expires before completion?
If completion has not happened before the expiry date, the offer lapses. The borrower has to apply for an extension, reapply to the same lender, or apply to a different lender. A reapplication is treated as a new application: new affordability check, new credit check, often a new valuation, and the rate available at the time of reapplication.
What is the offer validity for a new-build mortgage?
Most lenders offer 6-month validity as standard on new-build purchases, with the option of extension to 9 or 12 months where construction is delayed. Lenders typically reserve the right to revalue the property if completion slips materially beyond the original window, and the borrower's affordability may also be re-assessed.
If interest rates fall after my mortgage offer is issued, can I switch to a lower rate?
Many lenders operate a rate-switch facility allowing borrowers to move to a lower rate from the same lender before completion. The exact rules differ between lenders: some allow free switching within a window, others restrict it or charge a fee. If the lender does not offer a switch, the borrower can theoretically withdraw and reapply, but this can delay the conveyancing and is normally only worthwhile if the rate fall is material.
