How long does a mortgage offer last on a new build?
It depends on the lender. MoneyHelper says a full offer is usually valid for six months. The HomeOwners Alliance says most last three to six months, and some lenders allow longer for new builds. Here is what four lenders said on their own websites in October 2026. The bars show each offer out of 12 months, using the new-build figure where there is one.
Check the date on your own offer. It is the one that counts.
What happens if my mortgage offer expires before completion?
The offer may no longer be valid. MoneyHelper says to contact your lender as soon as possible, and warns that you may need to apply for a new mortgage, which could put the sale at risk. NatWest says that if your new build is delayed, you may have to start your application again. Barclays says delays beyond the offer's expiry could mean an extension or a new application.
A new application means the lender looks at you and the home again. MoneyHelper explains that an offer depends on the lender checking your finances and its own valuation of the property. A lender can still turn down an application if it isn't comfortable with the property. You may not keep the same deal. Loughborough Building Society's terms for mortgage brokers say that if an offer expires, the product (the particular deal, with its rate) may no longer be available. Newbury Building Society checks whether the deal is still available whenever it extends an offer. If it isn't, you choose from the deals it offers at the time.
Can you extend a mortgage offer?
Usually, but it isn't guaranteed. MoneyHelper says to ask your lender in writing, ideally a few weeks before the offer runs out. An extension may be anything from a month to six months, and lenders don't have to agree.
Lenders set their own terms. Nationwide doesn't extend new-build offers. NatWest's guidance for mortgage brokers says an extension can be asked for twice, for up to three months each time. That could take the offer to 12 months in total. Each extension depends on a fresh credit check and a new valuation of the property.
For its other offers, Nationwide allows a 45-day extension. When you ask, it wants your case number, the reason, and whether you've exchanged contracts. Have those ready, whoever your lender is.
Should I talk to a mortgage broker?
It can help. MoneyHelper says offers expire mainly because of delays in the conveyancing (the legal work of buying), as well as credit problems, changes in your circumstances and mistakes in the application. It says a broker may help reduce the chance of your offer expiring, by putting the application together for you. An offer can also be withdrawn if your income changes or you become unable to work. If your job or income changes while you wait, tell your lender or broker.
What happens if a new build is delayed?
Your contract should say. Under both consumer codes, the contract of sale must explain what happens if the home won't be ready by the date the builder gave, and when you can cancel. The Quality Code gives an excessive or unreasonable delay in finishing the home as one example of when you might be able to cancel.
The long-stop date is the last date by which the home must be completed. The Consumer Code for Home Builders suggests it should be no more than six months after the expected date for a house, if you exchange before the roof is on. For a flat, it suggests 12 months. If you exchange when the home is well advanced, it suggests two months for a house and four for a flat. The margin allows for delays outside the builder's reasonable control, such as an electricity substation or sewerage plant the estate needs. If the builder hasn't served notice to complete by then, you may be able to cancel. If you cancel for an unreasonable delay, the builder must repay your deposit, reservation fee and any prepayments in full within 28 days.
If you ask the builder for extra work, the date may move. The Consumer Code says your solicitors should record the change, and the long-stop date may need amending.
The completion date only becomes binding once the home is ready and the builder serves a completion notice. Under the Quality Code, that notice is usually expected to give you at least 14 calendar days. Tell your lender and solicitor the day it arrives.
Builders should keep you updated, and the dates they give should be accurate at the time. The Consumer Code suggests how precise the date should be at each stage. Before the foundations are done, the builder gives the quarter. Once the roof is on, it gives the month. Once the home is decorated and connected, it gives the week.
Before and after you exchange contracts
In England, Wales and Northern Ireland, before exchange, a reservation is "subject to contract": agreed, but not legally binding. After exchange, the contract commits both you and the builder to complete.
That is why the timing matters. The HomeOwners Alliance says some buyers who couldn't complete because their offer had expired, and couldn't get a new one, lost their deposit. It suggests negotiating for the long-stop date to fall on or before the day your offer expires. Your buildings insurance should also be in place from the day you exchange.
Your agreement in principle can expire too
An agreement in principle (AIP) is a lender's written statement of how much it might lend you. It isn't a formal offer. MoneyHelper says it is typically valid for 30 to 90 days. Barclays says its AIP usually lasts 90 days, and NatWest's lasts 30. Halifax says it is sometimes possible to renew the terms after 90 days, otherwise you reapply.
That matters if you reserve off-plan. NatWest says you can buy an off-plan new build with an AIP. If the build runs long, the AIP can lapse before you are ready to apply.
Can I get compensation if the build is late?
Sometimes. If the long-stop date passes, the Consumer Code for Home Builders says you may be able to claim out-of-pocket expenses through its independent dispute resolution scheme. For anything else, ask your solicitor what your contract allows. This page is general information, not legal or financial advice.