What Is a Mortgage Agreement in Principle and Will It Affect Your Credit Score?

If you're starting your home buying journey in the UK, you've likely heard the term “Agreement in Principle” (AIP) or “Decision in Principle.” It’s often one of the first steps estate agents and mortgage brokers recommend — but many first-time buyers are unsure what it actually means or whether it impacts their credit score.

In this guide, we explain what a mortgage Agreement in Principle is, why you might need one, how it can affect your credit report, and the best time to get one. We’ll also cover how lenders view them and what to watch out for.

What Is a Mortgage Agreement in Principle?

A mortgage Agreement in Principle (AIP) is a statement from a mortgage lender saying they would, in theory, be willing to lend you a certain amount based on your income, expenses, and credit history.

It’s not a binding offer — but it gives you a strong indication of how much you could borrow and shows estate agents and sellers that you’re a serious buyer.

What’s the Difference Between an AIP and a Mortgage Offer?

• An AIP is a provisional approval based on basic checks and self-reported details

• A formal mortgage offer is issued after the lender has fully reviewed your application, verified all documents, and completed a property valuation

Think of the AIP as a pre-qualification step to give you confidence and credibility when house hunting.

Why Should You Get an Agreement in Principle?

An AIP can:

• Help you understand your maximum borrowing limit

• Show estate agents and sellers you’re financially ready

• Speed up the buying process when you make an offer

• Reveal any issues in your credit history early

Some estate agents won’t even let you view a property without one.

What Information Do You Need to Get an AIP?

You typically need to provide:

• Your income and employment details

• Details of any regular outgoings (e.g. loans, credit card payments)

• Your address and personal information

• Consent for a credit check

You usually don’t need to submit documents at this stage — it’s more of a snapshot assessment.

Does Getting a Mortgage Agreement in Principle Affect Your Credit Score?

It can, depending on whether the lender uses a soft search or a hard search:

Soft Credit Search:

• Doesn’t leave a mark visible to other lenders

• Doesn’t impact your credit score

• Most common with online AIPs or broker tools

Hard Credit Search:

• Leaves a record on your credit report visible to other lenders

• May reduce your score temporarily if done multiple times in a short period

Tip: Always ask whether the lender or broker will carry out a soft or hard search before getting an AIP.

Can Multiple AIPs Damage Your Credit Score?

If you apply for multiple AIPs that involve hard credit checks, it can hurt your credit score and make it look like you’re desperate for credit — even if you’re just shopping around.

To avoid this:

• Limit the number of AIPs you get

• Use lenders or brokers that do soft searches

• Stick to one AIP at a time during your search

Read our guide on: How to Improve Your Credit Score in the UK

How Long Does an AIP Last?

Most AIPs are valid for 30 to 90 days, depending on the lender. If it expires before you’ve found a property, you can usually request an updated version — often without needing a new credit check.

Can You Be Rejected After Getting an AIP?

Yes. An AIP is not a guarantee of mortgage approval. You can still be declined later if:

• Your circumstances change (e.g. job loss, new debt)

• The property doesn’t pass the valuation

• You fail affordability checks or document verification

• Your credit file changes before full application

Always treat an AIP as a guide, not a promise.

Unique Insight: Some Lenders Use Internal Credit Scores in AIPs

While most people focus on the score from credit agencies, many lenders use their own internal scoring models during the AIP stage. This means:

• You could be approved for an AIP with one lender but rejected by another

• Your AIP might not reflect your full credit profile if based on limited information

That’s why working with a whole-of-market mortgage broker can help match you with the most suitable lender from the outset.

When Should You Get an Agreement in Principle?

The best time to get an AIP is before you start house hunting seriously. This gives you:

• A realistic view of what you can afford

• Greater credibility with estate agents

• Time to fix any issues that may arise from your credit report

If you’ve already found a property, get one as soon as possible — some sellers won’t consider your offer without it.

How to Get a Mortgage Agreement in Principle

You can get an AIP through:

• A bank or building society

• An online mortgage lender

• A mortgage broker (often quicker and easier)

Some tools provide instant AIPs with soft checks — ideal if you want to explore your options without affecting your score.

Related Reading

• Read our guide on: First-Time Buyer Mortgage Checklist

• Read our guide on: What Credit Score Do You Need for a Mortgage in the UK?

• Read our guide on: Can You Get a Mortgage with Bad Credit in the UK?

• Read our guide on: How Credit Card Debt Affects Your Mortgage Application in the UK

FAQs: Mortgage Agreements in Principle

Is an AIP the same as a mortgage offer?

No — an AIP is a provisional statement, not a formal mortgage offer. You’ll still need to go through a full application process.

Will my AIP affect my credit score?

Only if the lender uses a hard search. Ask upfront to confirm what type of credit check they perform.

Can I make an offer on a house with an AIP?

Yes — in fact, most estate agents expect you to have one when you make an offer.

How many AIPs can I get?

There’s no limit, but applying for multiple AIPs that use hard searches could negatively impact your credit score.

Do I need an AIP to view properties?

Not always — but many estate agents require one to show you a property or consider your offer seriously.

Final Thoughts

A mortgage Agreement in Principle is a valuable tool for any first-time buyer or home mover. It gives you a clearer picture of your borrowing power, strengthens your negotiating position, and helps uncover any potential issues early.

Just be mindful of how many you apply for and whether they involve soft or hard credit checks. Used wisely, an AIP can be a crucial first step on your journey to homeownership — but always remember it’s not a guarantee.

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