buying
Mortgage in principle: what it is, how long it lasts and what it does not promise
A mortgage in principle explained: what lenders check, whether it affects your credit file, why validity varies by lender and how it differs from a full offer.
- 3 min read
- Last reviewed 4 November 2026
- By Your Property Check team
Key answer
Part 1 of 7
What a mortgage in principle is
General information, not advice. Read our Terms. This page covers England and Wales, checked on 4 November 2026. GOV.UK's guide to buying a home says to get a decision in principle before you begin viewing properties. It describes it as a written statement from a lender giving an estimate of what you can borrow, and says it signals to sellers that you are serious about buying. The terms mortgage in principle, agreement in principle and decision in principle are used loosely, so ask a lender what they call theirs and what it covers.
Part 2 of 7
Mortgage in principle or full offer
| Item | Mortgage in principle | Full mortgage offer |
|---|---|---|
| What it is | A written estimate of what the lender would lend | The lender's formal offer on a specific property |
| When | Before you view or make an offer | After your offer on a home is accepted and you apply in full |
| Property checked | No | Yes, the lender arranges a mortgage valuation |
| Affordability | Based on what you tell them | A full assessment, including changes since the first check |
| Binds you | No, you need not take a mortgage with that lender | Check the offer terms |
| Source | GOV.UK, How to buy a home | GOV.UK and Citizens Advice |
Part 3 of 7
Does it affect your credit score?
GOV.UK says the majority of lenders carry out a credit search at this stage. Some run a soft enquiry, which does not affect your credit score, and others run a hard enquiry, which may. It advises asking which type a lender uses, because too many hard enquiries could negatively affect your credit score. We do not say which lenders use which, since that changes. Apply to as few lenders as you need, and ask first.
Part 4 of 7
How long does it last?
It varies by lender. GOV.UK does not give a period for a decision in principle, and the MoneyHelper pages on this topic were not available to us, so we give no figure. Ask the lender how long the statement is valid and what would make it lapse, such as a change in your income or circumstances. Ask what happens if it expires.
Part 5 of 7
Is a mortgage in principle a promise to lend?
No. GOV.UK says getting a decision in principle from one lender does not mean you have to take out a mortgage with them, and the full application comes later, after your offer is accepted. At that point the lender does a mortgage valuation and an affordability assessment, and considers any changes that might affect whether you can afford the repayments. So a mortgage in principle is a useful estimate, not a promise.
Part 6 of 7
What happens at the full application
Citizens Advice says lenders must check affordability and will ask for proof of your income, outgoings and spending habits. It says they consider how you would cope if interest rates rose or your income changed. It says it should take about three weeks from application to the formal offer, though timescales vary. The lender arranges a valuation, which you pay for in advance, usually when you submit the application. The valuation is not a survey, and Citizens Advice suggests considering a separate independent survey.
If you borrow a high share of the valuation, the lender may require extra insurance, which Citizens Advice calls a higher lending charge. It says this usually applies above 75% to 80% of the valuation and is usually a single premium added to the loan.
Part 7 of 7
Practical steps
- Ask which type of credit search the lender uses before you apply.
- Gather proof of income and spending, since these are asked for again at the full application.
- Use the figure as a budget, not a target, and add the other costs. Our guide to the cost of moving house shows the main lines.
- Check the stamp duty with the stamp duty calculator, or read about first-time buyer rates.
- Before offering, run the checks in our property check before buying a house.
- Avoid taking on new credit between the first statement and the final offer if you can, since the lender looks again at affordability.
This page is general information, not advice. For advice on which mortgage suits you, speak to a regulated adviser.
Our take
A mortgage in principle is a start, not a promise
It is a written estimate of what a lender might lend. It does not oblige you to take the mortgage and it is not a full offer, which comes after your offer on a home is accepted. Most lenders run a credit search. Our view: get one before you view homes, then treat the full application as the real test.
Once you have a figure, OfferCheck gives a plain-English risk report on any UK address before you offer: crime, flood, planning, tenure and more, every figure sourced. There is a free snapshot, and the full OfferCheck Report is from £4.99.
Our opinion, drawn from the facts on this page: not advice and not a forecast. We earn from OfferCheck reports and from introducing sellers to cash buyers, so weigh it with that in mind (see our disclosure). We are not authorised or regulated by the FCA.
Questions, answered
Frequently asked questions
What is a mortgage in principle?
How long does a mortgage in principle last?
Does a mortgage in principle hurt your credit score?
Is a mortgage in principle a promise to lend?
Do I have to take the mortgage from the lender that gave me one?
Where this comes from
Sources
Last reviewed 4 November 2026 by the Your Property Check team. This page is general information, not legal, tax or financial advice. For your own situation, speak to a conveyancing solicitor or another qualified professional.