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A mortgage in principle is an early estimate of how much a lender might lend; a mortgage offer is the formal offer made after the lender has assessed your full application and the property you want to buy. Get a mortgage in principle to help set a realistic budget and demonstrate readiness, but do not treat it as guaranteed approval. In the UK, it is not a legal requirement before making an offer on a home, even though an estate agent may ask to see one.
At a glance
| Name | Best for | Key distinction | Checked |
|---|---|---|---|
| Mortgage in principle (MIP), agreement in principle (AIP) or decision in principle (DIP) | Early budgeting and showing a seller or agent that you have begun checking your borrowing options | An initial estimate based on limited information; it is not a promise to lend and usually is not tied to a particular property | November 2026 |
| Mortgage offer | Moving toward buying a specific property after a full mortgage application | Issued after fuller checks of your finances and the chosen property; it sets out the lender’s offer and terms | November 2026 |
What is a mortgage in principle?
A mortgage in principle (MIP) is an initial indication from a lender of how much it might be willing to lend you. You may also see it called an agreement in principle (AIP) or decision in principle (DIP); these names generally refer to the same preliminary stage, although the lender’s process and terminology can differ. The amount is an estimate based on information you provide and checks the lender chooses to make, not a final decision on a mortgage.
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Expect to provide initial details about your income, spending, deposit and circumstances. The exact questions and checks vary by lender. An MIP is not a substitute for a full affordability assessment, and the estimate may change if the information is incomplete or your circumstances change. For help thinking through borrowing and other costs, see MoneyHelper’s guide to how much you can afford to borrow.
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Is a mortgage in principle the same as a mortgage offer?
No. A mortgage in principle is an early estimate; a mortgage offer follows a full application and the lender’s assessment of you and the property you intend to buy. The stages serve different purposes, and an MIP does not guarantee that the lender will make an offer.
| Mortgage in principle | Mortgage offer | |
|---|---|---|
| When it happens | Early in the search, before a full application | After a full application and lender assessment |
| What it tells you | An estimate of the amount the lender might lend | The lender’s offer for the application and chosen property |
| Financial checks | Based on limited information and lender-specific initial checks | More detailed evidence and affordability checks |
| Property assessment | Usually made before you have chosen a property, so it is generally not property-specific | The lender assesses the particular property, including a valuation |
| Does it commit the lender? | No; it is not a guarantee of approval | It is a formal offer, but read its terms and required steps; you are not obliged to accept it |
| Typical validity | MoneyHelper says typically 30–90 days; lender rules vary | MoneyHelper says usually six months; lender rules vary |
The formal offer is a regulated mortgage document for a regulated mortgage contract. The FCA Handbook’s MCOB 6.4.1 requires a firm making an offer to provide an offer document containing an illustration. Read the document itself carefully: it contains the lender’s terms, and you should check what you need to do next and when the offer expires. The requirement is set out in the FCA’s Mortgage and Home Finance Conduct of Business Sourcebook.
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It is sensible to get one early, often before viewing homes, so you have an estimate to guide your search. GOV.UK advises buyers to get a decision in principle before viewing. That is practical guidance, not a legal condition for viewing or making an offer.
MoneyHelper says there is no legal requirement to have an MIP before making an offer on a property. In practice, an estate agent may ask for one, particularly in a competitive market, to gauge whether you have considered how you would finance a purchase. If you do not yet have one, ask whether the agent will accept other evidence of your readiness, and remember that an agent’s request does not turn the MIP into final mortgage approval.
There is an important distinction between an offer you make to buy a home and a mortgage offer from a lender. A seller can accept your proposed purchase price before you have a formal mortgage offer. The next steps toward financing the purchase are to make a full application and have the lender assess your case and the property.
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For the official sequence and practical home-buying guidance, see GOV.UK’s guide to buying a home. It advises buyers to get a decision in principle before viewing, while MoneyHelper explains that it is not a legal prerequisite to making an offer.
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What happens after my offer on a property is accepted?
Once the seller accepts your offer, you can make a full mortgage application. You do not have to apply to the lender that gave you the MIP: GOV.UK says you can apply to that lender or another provider. Compare the actual mortgage terms and suitability rather than assuming an initial estimate locks you in.
- Choose a lender and make a full application. Provide the information and documents requested. The lender’s requirements vary, but may include proof of identity and address, income details, bank statements, evidence of your deposit, and information about any gifted deposit.
- Answer follow-up questions promptly. Underwriters may need more information to assess your circumstances. Missing, inconsistent or outdated details can mean the lender has to ask for clarification, and the estimate from your MIP may not reflect the result of these fuller checks.
- Wait for the lender’s affordability and property assessment. The lender considers whether the mortgage is affordable and assesses the particular home, including a valuation. This is not the same as a condition survey for your benefit: GOV.UK says a lender’s valuation is to establish whether it is willing to lend against the property, may not involve a physical inspection, and is not a survey.
- Review the formal offer if the application succeeds. Read the offer document, illustration, conditions and expiry date. If the lender does not offer the amount or terms you expected, ask it or your adviser to explain the decision and what options remain.
MoneyHelper’s overview of the mortgage application process explains the move from initial borrowing checks to a full application and property assessment. The specific documents and processing steps depend on the lender and your circumstances.
Can I be declined after a mortgage in principle?
Yes. An MIP is not a guarantee of a mortgage offer, so a lender can decline the full application or offer a different amount or terms after its more detailed assessment. The initial indication may not account for all the evidence, affordability details or property-specific issues that emerge later.
The valuation is one reason the outcome can differ: the lender is deciding whether it is willing to lend against the property as well as reviewing your finances. A valuation that does not support the lender’s assessment of the property can affect the application. The lender may also need evidence that was not reviewed at the MIP stage, such as bank statements or proof of the deposit. Do not rely on the initial figure as a final borrowing limit, and avoid committing to costs you cannot afford on the assumption that the MIP guarantees funding.
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If the lender’s full assessment changes the result, ask what part of the application or property assessment led to the decision. You can then consider whether more information is needed, whether a different mortgage amount or property is realistic, or whether to approach another lender. A previous MIP does not prevent you from applying elsewhere, but another lender will make its own assessment.
Does a mortgage in principle affect my credit score?
It depends on the lender and the type of credit search it uses. MoneyHelper says some lenders use a soft search and others use a hard check, so do not assume that every MIP works the same way. Ask the lender which search it will make before you apply if the distinction matters to you.
A soft search is not visible to other lenders in the same way as a full credit application search; a hard search can leave a record on your credit file. Nationwide, for example, says its own Decision in Principle uses a soft check, while a full mortgage application involves a formal check. That describes Nationwide’s process, not a rule for all providers. Check the lender’s current explanation of its own search and what it means for your credit file.
See MoneyHelper’s explanation of what happens when you get an MIP and Nationwide’s Decision in Principle information for these provider-specific distinctions.
How long does a mortgage in principle or mortgage offer last?
Validity depends on the lender and product. MoneyHelper says an MIP typically lasts 30 to 90 days, while Nationwide says its own DIP is valid for 90 days. Treat those as guidance, not a universal deadline: check the date and terms on your own document and ask the lender what to do if it expires before you are ready to apply.
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A full mortgage offer usually lasts longer. MoneyHelper says it is usually valid for six months, but the offer document and lender determine the actual expiry date. An extension may sometimes be possible, but the lender decides and is not obliged to grant one. Contact the lender before the offer expires if your purchase is delayed; do not assume an extension is automatic. MoneyHelper’s guide to how long mortgage offers last discusses the typical period and possible extensions.
MoneyHelper also gives two to four weeks as a typical time to receive an offer after applying. This is an estimate, not a service guarantee: timing can depend on the lender’s workload, the complexity of your case and how quickly requested information is supplied. Build in room for questions or a valuation rather than planning around the shortest possible timeline.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What should I check before relying on an MIP?
Use the document as a planning aid and verify its limits directly with the lender. In particular, check:
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- Which credit search is used. Ask whether the MIP involves a soft search or a hard check, and what the lender’s explanation means for your credit file.
- What information the estimate relies on. Make sure your income, commitments, deposit and personal details are accurate. Tell the lender if an important circumstance changes.
- Whether the estimate is a maximum, not a budget recommendation. A lender’s indication of what it might lend is not the same as what you can comfortably afford after housing costs and other spending.
- What the seller or agent is asking for. An MIP may demonstrate preparation, but it is not the lender’s approval of the selected home.
If you need individualised advice, GOV.UK says a mortgage broker can provide advice and may charge a fee. MoneyHelper distinguishes advisers tied to a lender from independent brokers who can discuss products from multiple providers. Understand the adviser’s scope and any charges before proceeding; the MIP itself does not require you to use a broker.
What is the simplest way to remember the difference?
Think of the MIP as an early borrowing estimate for planning and house-hunting, and the mortgage offer as the lender’s formal response after assessing your full application and chosen property. Get the estimate early if it helps you search and demonstrate readiness, but base your purchase plans on the full application, the formal offer and its conditions—not on the MIP alone.
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Frequently Asked Questions
Can I use a mortgage in principle from one lender to apply to another?
Yes. GOV.UK says you can make your full application to the lender that issued the decision in principle or to another provider. The new lender will make its own assessment, so the first lender’s estimate does not bind the second.
Do I need a mortgage broker to get a mortgage in principle?
No. A broker is one possible route to mortgage advice, not a requirement for obtaining an initial decision. GOV.UK notes that brokers may charge a fee; ask what advice they provide and what it costs before agreeing to use one.
What if my mortgage offer expires before the purchase completes?
Contact the lender as soon as you know the transaction may run past the offer’s expiry date. An extension may be possible, but the lender decides and is not required to grant one; the lender may explain what updated information or steps it needs.
Does a lender’s mortgage valuation replace a home survey?
No. GOV.UK says the lender’s valuation is to decide whether it is willing to lend against the property, not to provide a condition survey for the buyer. It may not involve a physical inspection, so do not treat it as a substitute for a survey.
