An agreement in principle (AIP) - which you may also see called an approval in principle, a decision in principle or a mortgage in principle - is a lender's written indication of how much it would be prepared to lend you, based on a quick check of your income, outgoings and credit file. It is not a mortgage offer, it takes minutes to obtain, and at every major lender it uses a soft credit search that leaves no mark on your credit score.
Key takeaway: An agreement in principle confirms two things: your credit file has passed the lender's soft search, and the income you have stated supports the amount you want to borrow. That is enough to view properties and make offers with confidence. It is not approval, because nothing has yet been evidenced, valued or underwritten.
[[stats: Same day = How quickly an AIP can usually be arranged | Soft = The credit search used, so your score is unaffected | 30-90 = Days it lasts, depending on the lender]]
What is an agreement in principle?
An agreement in principle is a preliminary statement from a lender saying how much it would probably lend you.
To produce one, the lender takes your income, your regular outgoings, your deposit and a light-touch look at your credit file, then runs those numbers through its affordability model. What comes back is a figure and a certificate. What does not come back is a commitment: the lender has not seen a payslip, has not valued a property, and has not underwritten anything.
That distinction is the single most misunderstood part of the process, and it is worth being clear about before you rely on one.
Agreement in principle, approval in principle, decision in principle - what is the difference?
There is no difference. These are all names for the same document, and the name changes with the lender rather than the product.
Across lender websites, estate agents and brokers you will see agreement in principle (AIP), approval in principle, acceptance in principle, decision in principle (DIP) and mortgage in principle (MIP) used interchangeably, and some lenders add their own branding on top, such as calling it a mortgage promise. There is no difference in what you receive, in what the lender has actually checked, or in what it commits either side to.
So if an estate agent asks for a decision in principle and the certificate in your inbox says agreement in principle or approval in principle, you already have exactly what they are asking for.
What does an agreement in principle look like?
It is usually a short certificate, normally a one or two page PDF or an online confirmation, rather than a lengthy legal document.
A typical agreement in principle shows the lender's name, your name, the maximum amount the lender indicates it would be prepared to lend, the date it was issued and how long it remains valid, and a reference number. Some lenders also state on the certificate that the figure is subject to a full application, valuation and underwriting.
Just as telling is what it does not contain. There is no interest rate, no monthly payment and no property address, because none of those has been assessed at this stage. It is a statement about you, not about a specific home or deal.
Why is an agreement in principle so important?
There are two reasons, one practical and one that buyers tend to value more than they expect to.
The first is peace of mind. Without an AIP you are viewing properties on an assumption. With one, you know your budget is realistic and that your credit file has already passed a lender's initial check, so you are not spending your weekends looking at homes that were never within reach.
The second is simply that estate agents typically ask for a copy when you make an offer. Having one to hand means you can move at the moment it matters, rather than arranging it under pressure while another buyer is doing the same.
Does an agreement in principle guarantee a mortgage?
No, and this is one of the most common misconceptions about the whole process.
An agreement in principle means two specific things have been checked and passed: your credit file has cleared the lender's soft search, and the income you have stated is sufficient for the loan amount you asked for. That is genuinely useful, but it is a long way from full approval. Nothing has been evidenced, no property has been assessed, and no underwriter has looked at your case.
How long does an agreement in principle last?
Between 30 and 90 days, and the range varies more between lenders than most guides suggest. Here is what six major UK lenders state on their own published pages.
[[table: Lender | How long the AIP lasts | Credit search used ;; NatWest | 30 days | Soft search ;; Santander | 60 days | Soft search ;; HSBC | Typically 60 to 90 days | Soft search ;; Halifax | Usually 30 to 90 days | Soft search ;; Nationwide | 90 days | Soft search ;; Barclays | 90 days | Soft search]]
Lender terms correct as at August 2026, taken from each lender's own published guidance. Criteria change, so confirm the current position before relying on it.
It is worth knowing which end of that range yours sits at, particularly if your property search runs on. In practice, though, an expired AIP is rarely a problem. Renewing is usually a straightforward resubmission rather than starting the whole process again, and because it is another soft search there is no cost to your credit file for doing so.
Does an agreement in principle secure an interest rate?
Usually not. Almost all lenders treat the AIP purely as an affordability and credit check, with the rate decided later when you submit a full application.
A small number of lenders work differently and will let you hold a rate from the agreement in principle stage. Where that option is available it can be a real advantage, because it may let you lock in a rate before any further rises take effect.
[[table: Lender | How the rate is held ;; Nationwide | A product can be reserved at agreement in principle stage, provided the mortgage offer is issued within 90 days of the reservation ;; Aldermore | A rate is secured for 30 days from submission of the agreement in principle]]
Correct as at August 2026. Product reservation terms vary between lenders and change over time, so confirm the current position before relying on it.
Good to know: Reserving a rate early removes uncertainty rather than guaranteeing a saving, since nobody can predict which way rates will move afterwards. Whether it suits you depends on your likely timescale and on the individual lender's rules, so it is worth raising with your adviser rather than assuming it is always the better route.
Does an agreement in principle affect your credit score?
No, not at the lenders in the table above. All six confirm on their own published pages that the agreement in principle stage uses a soft search, which is visible only to you on your credit file and has no effect on your score.
This is worth stating plainly, because a warning circulates widely online that "some lenders run a hard check at AIP stage". Every one of the six major lenders reviewed here publishes the opposite. That does not mean no lender anywhere runs a hard search at this stage, and a small number of specialist lenders work differently, so it is a fair question to ask before you proceed. But the blanket warning is not accurate for the mainstream lenders most buyers will use.
The hard search comes later, at full application. That one is recorded and visible to other lenders, which is why making a series of full applications in quick succession is genuinely worth avoiding, while collecting an AIP is not.
If you are worried about how your file looks before you start, our guide to credit scores and mortgages covers what lenders actually look at, which is rarely the three-digit number people expect.
How do you get an agreement in principle?
The process is quick, and in most cases can be completed the same day.
[[steps: Gather your numbers|Your gross annual income, any additional income such as overtime, bonus or commission, your regular credit commitments, and how much deposit you have. ;; Decide which lender fits|This is the step most buyers skip. The right lender depends on your income type, credit history and deposit, and getting it right here makes the AIP a realistic preview of your actual application. ;; Submit the details|Either directly with the lender or through your broker. The lender runs a soft search and its affordability model. ;; Get your certificate|If accepted, you receive a document confirming the indicative amount, which you can send to estate agents. ;; Start viewing with a real budget|You now know the ceiling you are working to, rather than guessing.]]
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Which lender should you get your agreement in principle with?
It matters less than most people assume. An agreement in principle commits you to nothing, so if a better option appears before you submit a full application, you are free to take it.
That said, an AIP is far more useful when it comes from a lender that genuinely fits your circumstances, because it then acts as a realistic preview of what your actual application will look like rather than a number from a lender you were never going to use. Quanstrom Financial always aims to arrange your agreement in principle through a lender suited to your individual situation, and a lender might be selected for reasons such as:
- Your visa status, if you are not a UK or Irish citizen
- Your credit history, and which lenders are comfortable with anything showing on your file
- The borrowing amount required, since income multiples vary considerably between lenders
- How your income is treated, whether you are employed, self-employed, on a contract, or paid with a significant share of overtime, bonus or commission
- The size of your deposit and where it has come from
- Whether that lender allows you to hold a rate at this stage
Can you make an offer on a house without an agreement in principle?
You can, but many estate agents will not put your offer to the seller until they have seen one, and some will not book viewings without it.
From the agent's side the logic is straightforward: they have a duty to pass on offers, but they also have a seller who wants to know a buyer can actually complete. An AIP is the cheapest available evidence that you can, and in a competitive situation between two similar offers, the buyer holding one is the safer bet.
Can you still be declined after an agreement in principle?
Yes. An AIP is an indication based on unverified information, and the full application is where that information gets checked. Most declines at this stage trace back to a small number of causes.
[[accordion: The figures I gave were an estimate|An AIP is generated from what you type in. If your actual income, bonus treatment or monthly credit commitments differ from your estimate once payslips and bank statements are checked, the affordability calculation changes with them. ;; Something on my credit file came up|The soft search at AIP stage is a lighter look than the full check at application. A missed payment, a default or an account you had forgotten can surface later even though the AIP passed. ;; My circumstances changed after I got it|Changing jobs, starting a probationary period, taking out a car finance agreement or a buy-now-pay-later balance between AIP and application can all move the outcome. ;; The property itself was the problem|The AIP assesses you, not the house. Down-valuations, non-standard construction, short leases and flats above commercial premises are all assessed only once a specific property is named. ;; I applied to a lender that was never the right fit|This is exactly what a mortgage broker at Quanstrom Financial is there to prevent. We work to place you with a lender whose criteria suit your circumstances right at the outset, so a mismatch that was visible from the start does not surface as a decline weeks later.]]
None of these make an AIP pointless. They make it what it is: a well-informed indication, not a decision. The way to keep the gap between the two small is to have the affordability conversation properly at the start, rather than treating the certificate as the finish line.
Agreement in principle vs mortgage offer
These are two different documents at two different stages, and conflating them is where most disappointment comes from.
[[table: | Agreement in principle | Mortgage offer ;; What it is | An indication of what a lender would probably lend | A formal, binding commitment to lend ;; Evidence checked | Self-declared figures, soft credit search | Payslips, bank statements, full credit check, property valuation ;; Property involved | No, it is not tied to a specific home | Yes, it relates to one named property ;; How long it takes | Often the same day | Typically a few weeks after full application ;; How long it lasts | 30 to 90 days depending on lender | Usually around 3 to 6 months depending on lender ;; Can it be withdrawn | Yes, it is not a commitment | Only in limited circumstances, such as a material change]]
How much could you actually borrow?
An AIP will give you one lender's answer. It is worth understanding the range before you accept it, because income multiples vary considerably between lenders and the first figure you are quoted is not necessarily the highest available to you.
Most lenders work somewhere between 4.5 and 6 times income, with a broad base of lenders at the lower end and a much smaller pool prepared to stretch further. A small number of specialist lenders go beyond that. Enter your own figures below for an indication.
[[calc:borrowing]]
For a fuller explanation of how different income types are treated, including overtime, bonus, commission and self-employment, see our guide to how much you can borrow for a mortgage.
What happens after you get one?
The AIP is the start of the process rather than a milestone in it. Once you have one, you can view properties knowing your ceiling, offer with credibility, and move quickly when you find the right place.
When your offer is accepted, the full application begins: documents, a hard credit check, a valuation and underwriting. Keep your finances still during this period. Avoid new credit agreements, avoid changing jobs if you can, and keep your accounts tidy. Nothing derails a straightforward application faster than a new car finance agreement taken out in the month before completion.
If you are buying your first home, our first-time buyer guide walks through the whole sequence, including the costs that catch people out.
Frequently asked questions
How long does an agreement in principle last?
Between 30 and 90 days, depending on the lender. NatWest's lasts 30 days, Santander's 60, and Nationwide's and Barclays' both run for 90. If yours expires before you have found a property, renewing it is usually a simple resubmission.
Is an approval in principle the same as an agreement in principle?
Yes. Approval in principle, agreement in principle, acceptance in principle, decision in principle and mortgage in principle are all names for the same document. Lenders simply brand it differently, and there is no difference in what has been checked or what it commits anyone to.
What is the difference between an agreement in principle, a decision in principle and a mortgage in principle?
There is no difference. Agreement in principle, decision in principle and mortgage in principle are simply different lenders' names for the same document, and the terms are used interchangeably across the industry.
Does an agreement in principle mean you are fully approved for a mortgage?
No. It means your credit file has passed the lender's soft search and the income you stated is sufficient for the loan amount requested. Nothing has been evidenced or underwritten at that point, so it is an indication rather than approval.
What does an agreement in principle look like?
It is a short certificate, usually a one or two page PDF, showing the lender's name, your name, the indicative amount the lender would be prepared to lend, the issue date and validity period, and a reference number. It does not include an interest rate or a property address, since neither has been assessed at that stage.
Does an agreement in principle secure an interest rate?
With almost all lenders, no. A small number allow it: Nationwide lets a product be reserved at agreement in principle stage provided the mortgage offer is issued within 90 days, and Aldermore secures a rate for 30 days from submission of the agreement in principle.
Does an agreement in principle affect your credit score?
No. All six major lenders reviewed here use a soft credit search at AIP stage, which is visible only to you and has no effect on your score. The hard search that other lenders can see happens later, at full application.
What happens if your agreement in principle expires?
Very little. You simply ask for a new one, which normally means resubmitting the same details for a fresh soft search. Because no hard search is involved, an expired AIP costs you nothing beyond the few minutes it takes to renew.
Can you make an offer on a house without an agreement in principle?
You can, but many estate agents will not forward your offer to the seller or book viewings until they have seen one, since it is the simplest evidence that you can finance the purchase.
Can you be declined a mortgage after an agreement in principle?
Yes. An AIP is based on information you have declared rather than verified, so a decline can follow if your actual income differs, something surfaces on the full credit check, your circumstances change, or the property itself does not meet the lender's requirements.
Do first-time buyers need an agreement in principle?
It is not a legal requirement, but for first-time buyers it is close to essential in practice. It confirms your budget is realistic before you start viewing, and most estate agents will want to see one before putting your offer forward, so it is usually one of the first steps in the buying process.
Does it matter which lender your agreement in principle is with?
Not as much as people assume, since an AIP does not oblige you to proceed with that lender. It is more useful, though, when it comes from a lender that suits your circumstances, because it then reflects what your real application is likely to look like.
Can you have more than one agreement in principle at the same time?
Yes. Because each one uses a soft search, holding AIPs from more than one lender does not damage your credit score. In practice it is rarely necessary, since the more useful exercise is identifying the right lender first rather than collecting certificates.
Is an agreement in principle the same as a mortgage offer?
No. An AIP is an indication based on unverified figures and is not tied to a property. A mortgage offer is a formal commitment made after full underwriting, a hard credit check and a valuation of the specific home you are buying.
Can you offer more than your agreement in principle amount?
You can offer whatever you like, but you would need either a larger deposit to cover the difference or a fresh AIP at a higher figure. If your offer exceeds what the certificate shows, expect the estate agent to ask how the gap is being funded.
Do you need an agreement in principle to view a property?
Not always, but an increasing number of estate agents ask for one before booking viewings, particularly on properties attracting significant interest. Having one ready avoids losing a viewing slot while you arrange it.
How long does it take to get an agreement in principle?
Often minutes, and in most cases the same day. The part worth spending time on is not the application itself but deciding which lender to approach, since an AIP from a lender whose criteria do not fit your circumstances is of limited value.
Written by Toby Quanstrom CeMAP, Director at Quanstrom Financial, a whole-of-market mortgage broker based in Eastbourne, East Sussex.
Your home may be repossessed if you do not keep up repayments on your mortgage.
This article is for information only and does not constitute personal advice. Lender criteria change regularly, so please get in touch for guidance based on your own circumstances.
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