My buyer has a mortgage in principle. Is that enough?

A mortgage in principle, also called an agreement in principle or a decision in principle, is a lender's early indication of how much it might lend a buyer, based on limited information and usually a soft credit check. It is a useful sign that a buyer has spoken to a lender and has a rough figure to work with. It is not the lender committing money to your property.

What does a mortgage in principle actually prove?

It proves your buyer has started, not that they can finish. Nationwide's own guidance states that a decision in principle is only an indication of how much a lender is prepared to lend based on limited information, and that having one does not guarantee the full application will succeed.

How long does a mortgage in principle last?

Between one and three months for most lenders, and the exact window is set by each lender rather than by any general rule. Nationwide states that its decision in principle is valid for 90 days. Santander states that a decision in principle with them lasts 60 days.

The date on the certificate matters more than usual this year. Zoopla's House Price Index of 27 August 2026 put the effect of higher mortgage rates at a 9% reduction in buyer purchasing power, and Rightmove's tracker on 17 August 2026 showed the average two-year fixed rate at 5.09%, up from 4.95% a year earlier.

So a certificate issued in the spring may not survive a fresh affordability check now. Asking a buyer when theirs was issued is a fair, unaggressive question, and the answer tells you a great deal.

How do I check my buyer is genuinely able to proceed?

1. 1. Ask for the certificate and its date

   Ask your agent for a copy of the mortgage in principle and note the issue date and the lender. Anything over about two months old is worth refreshing before you rely on it.

2. 2. Ask what the deposit is and where it is

   Find out the deposit percentage and whether the money is already in the buyer's account, still in an investment, or coming from family. Each of those carries a different delay and a different risk.

3. 3. Ask whether they need to sell first

   A buyer who must sell their own home is only as secure as their own buyer. Ask whether their sale is agreed, at what stage, and whether the chain below them has been checked.

4. 4. Ask your agent what they verified

   Agents are required to carry out customer due diligence on a buyer before contracts are exchanged under the money laundering regulations, so ask what identification and proof of funds they have already seen.

5. 5. Set a date for the full application

   Agree with your buyer, in writing through the agent, that the full mortgage application will be submitted within a set number of working days of the offer being accepted. This is the single clearest test of intent.

6. 6. Watch what they spend, not what they say

   Real commitment shows up as money leaving the buyer's account: a solicitor instructed and paid on account, a survey booked, an application submitted. Enthusiasm at a viewing costs nothing.

What is normal here, and what is a red flag?

• Normal: a mortgage in principle from a lender or broker, produced within a day or two of the offer.
• Normal: a full application taking two to six weeks to turn into a formal mortgage offer once submitted.
• Normal: the lender asking for extra payslips, bank statements or an explanation of a transaction.
• Worth a question: a certificate that is several months old, or one the buyer cannot produce at all.
• Worth a question: a buyer who will not name their lender or broker, or who avoids giving a date for the application.
• Red flag: weeks passing with no application submitted, no solicitor instructed and no survey booked.

Should I take my house off the market on a mortgage in principle alone?

That is your decision, and the honest answer is that it depends on how much else the buyer has done. Coming off the market is the point at which you stop having alternatives, so it is worth pairing with something the buyer has also committed.

The risk is real and it is measurable. TwentyEA data reported in April 2026 put the UK fall-through rate at 23.7% in the first quarter of 2026, roughly one agreed sale in four, and analysis of that data found 38% of fall-throughs happen within the first four weeks of a sale being agreed.

• Instructing your own solicitor early is cheap, reversible and keeps the sale moving, so do that straight away.
• Larger, harder-to-recover spends, such as a leasehold management pack or your own searches, sit better once the buyer's application is in.
• Coming fully off the market is the biggest step you take, so tie it to the buyer having spent their own money, not to their word.

None of this is about distrusting your buyer. It is about moving in step with them rather than ahead of them, so that if their finance does not come through you have lost weeks rather than months.

A mortgage in principle tells you a buyer has started. A submitted application tells you they have committed.

Where does ValuQ fit in?

ValuQ gives UK homeowners free, side-by-side property valuations from competing local estate agents. Seeing several agents set out their pricing evidence and their plan on one screen puts you in a stronger position to judge, later on, whether the buyer in front of you is the right one to hold out for.