An Agreement in Principle (AIP) is a quick affordability check that helps you house-hunt with confidence. This guide explains what an AIP is, how lenders assess you, whether it affects your credit score, how long it lasts, and how to get one the right way without tripping yourself up.
Feb 9, 2026
If you’re viewing homes, speaking to estate agents, or getting ready to make an offer, you’ll hear this early on: “Have you got an AIP?”
An Agreement in Principle (AIP) is one of the simplest steps in the mortgage process, but it’s also one of the most misunderstood. Some people think it’s a guarantee. Others avoid it because they’re worried it will wreck their credit score. Both takes can cause problems.
As Will Sharman puts it: “An AIP isn’t the finish line, it’s the starting gun. Get it right and everything else moves faster.”
This guide breaks down what an AIP actually is, how it works, what lenders look at, and how to get one properly.
An Agreement in Principle is a lender’s initial indication of how much they may be willing to lend you, based on the information you give them and an early credit check.
You might also see it called:
Different name, same general purpose: it tells you and the estate agent that, on paper, you look mortgageable for roughly a certain amount.
An AIP is not a formal mortgage offer. It is usually subject to things like:
When people say “AIP mortgage” they usually mean “I’ve got an AIP for a mortgage”. The AIP isn’t a mortgage product itself, it’s a pre-check that sits before the full application.
Think of it like this:
A typical AIP will show:
What it usually does not show:
Most of the time, yes.
AIP, DIP, and MIP are commonly used interchangeably in the UK. The key differences are usually lender-specific, not concept-specific.
What matters more than the label is:
Often, yes.
Most lenders will do some form of credit check at AIP stage. That check can be either:
You should always know which one it is before you apply.
If you’re getting an AIP through a broker, they should be telling you what the lender uses and whether it leaves a mark.
It depends on the type of search and how many you do.
Even if the score drop is temporary, the bigger issue is how it looks. A cluster of hard searches can make you look desperate for credit, even if you are not.
Will’s view is simple: “The goal isn’t to collect AIPs like Pokémon cards. One strong AIP, done properly, beats five rushed ones every time.”
Most AIPs last somewhere around 30 to 90 days, but it varies by lender.
If it expires, it does not mean you are rejected. It just means you might need to refresh it with updated info and another check.
If you’re early in your search and not viewing seriously yet, it can be smarter to wait a bit, or get guidance on when the timing makes sense, especially if the lender uses hard searches.
Lenders are trying to answer one question: can this person likely afford a mortgage of this size?
At AIP stage they usually look at:
The AIP is only as good as the information going into it. If you guess your income, hide a debt, or “forget” a credit card, your AIP can be misleading, and the real application can fall apart later.
You’ve got two main routes: direct with a lender, or via a broker.
Before you apply, make sure you know:
You do not need a folder of paperwork for most AIPs, but you do need accurate numbers.
Many lenders offer AIPs online in minutes. That’s fine, as long as you understand the credit search type and you don’t spam applications.
A broker route is often better when:
Once you have an AIP, avoid doing anything that creates problems before the full application, like:
Yes. Most major lenders offer it online.
Just be careful with two things:
Online AIPs are convenient, but they can also give people false confidence if they’ve entered rough numbers or ignored existing commitments.
You can, but you should have a reason.
The only time multiple AIPs make sense is if you’re testing genuine lender differences because your case is slightly unusual, or you’re comparing options in a controlled way.
If you’re doing multiple AIPs because you are panicking or clicking around, that’s a self-inflicted wound.
If you want multiple checks, do it through someone who understands lender criteria, so you don’t rack up hard searches for no reason.
No.
An AIP can still fall apart if:
That said, a well-done AIP is usually a strong sign you’re on the right track.
Some AIPs ask for your deposit figure, some assume one, and some give a result that only makes sense with a certain deposit.
Either way, deposit size matters because it affects:
If you’re trying to buy with a smaller deposit, the AIP needs to be aligned to lenders who actually play in that space, otherwise you’re wasting time.
Typically:
You usually do not need to upload payslips at AIP stage, but you will later, and the figures must match.
In most cases, yes.
Many estate agents will not take an offer seriously without one, especially in competitive areas. Even when they do, having an AIP makes you look organised and reduces the risk of your offer being treated as a time-waster.
An AIP also stops you wasting your own time. If you are viewing homes above what you can realistically borrow, you’re setting yourself up for a messy reality check later.
Here are the big ones we see:
MBNM’s job here is not to “get you an AIP”. It’s to make sure the AIP you get is:
That means fewer surprises, fewer delays, and fewer last-minute scrambles when you find the right home.
Usually a PDF or a reference number confirmation page showing your indicative borrowing amount and validity period.
Fairly reliable when your details are accurate and your situation is straightforward. Less reliable when income is complex or details are missing.
No. An offer is the lender saying yes to a mortgage for a specific property, after full checks.
No. You should avoid careless, repeated hard searches. A properly planned AIP is part of buying a home sensibly.
An AIP is not a trophy, it’s a tool. Use it at the right time, with the right lender, based on accurate information, and it makes your entire purchase smoother.
If you want MBNM to sense-check your numbers before you trigger any applications, do that first. It’s a lot easier to prevent a mess than to clean one up later.
Your home may be repossessed if you do not keep up repayments on your mortgage.
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Your Home (or property) may be repossessed if you do not keep up repayments on your mortgage or any other debts secured on it.
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