Agreement in Principle: everything you need to know

Agreement in Principle (mortgage in principle): the basics

An Agreement in Principle (often called a mortgage in principle, decision in principle, or approval in principle) is a document from a lender that gives an indication of how much you may be able to borrow for a mortgage.

It’s designed to help you understand your likely borrowing range early in the buying process, and it can show estate agents and sellers that you’re a serious buyer.

Non-binding, but still useful

An Agreement in Principle is not a mortgage offer. It’s based on information provided at the start of the process, and it doesn’t replace the full affordability checks and property assessment that happen later.

What an Agreement in Principle is used for

For many home buyers, an Agreement in Principle can:

Give you a clearer idea of what you can afford to bid for
Strengthen your position when making an offer
Help you plan the next steps with less uncertainty

It’s particularly common for first-time buyers who are still learning how the mortgage process works.

How to get an Agreement in Principle

You can usually apply for an Agreement in Principle through a lender or via a mortgage adviser/broker. The process typically involves providing key personal and financial information.

While the exact steps vary, you’ll generally be asked to confirm details such as:

Your identity details (for example name, date of birth, and current address)
Address history (often covering a set period)
Your income
Your monthly outgoings and existing financial commitments

Once submitted, the lender will review the information and provide a written indication of the borrowing amount they may be willing to consider.

What documents and information you may need

Most Agreement in Principle applications focus on information, rather than full documentation. However, you should expect to be asked for details that allow the lender to assess affordability.

Common information includes:

Income details
Existing credit commitments (for example loans, credit cards, or other monthly payments)
Estimated expenditure and household costs
Address history

If you’re self-employed, have multiple income streams, or your income varies, you may be asked for additional detail to help the lender understand how stable it is.

How long does an Agreement in Principle last?

An Agreement in Principle is usually valid for a limited period, commonly between 30 and 90 days, depending on the lender.

If it expires before you complete the next stage of the buying process, you may need to renew it. Keeping an eye on timing can help avoid delays when you’re ready to move forward.

Does an Agreement in Principle affect your credit score?

In many cases, applying for a mortgage in principle involves a credit check.

Whether it affects your credit file can depend on the type of check used:

A hard search can leave a visible footprint on your credit record and may affect your credit rating
A soft search is typically not visible to other lenders in the same way

Because different lenders and processes can use different types of checks, it’s worth being mindful if you’re applying for multiple agreements in principle around the same time.

Why multiple applications can matter

If there are several hard searches in a short period, it may make your credit profile look more “active” than usual. That doesn’t automatically mean you’ll be declined later, but it can be a factor worth managing.

Can you be rejected after getting an Agreement in Principle?

Yes. An Agreement in Principle is not a guarantee.

At the Agreement in Principle stage, the lender’s view is based on a relatively high-level assessment of affordability and the information you’ve provided.

Later, when you apply for the full mortgage, the lender will typically carry out more detailed checks, including:

A fuller affordability assessment
Verification of income and commitments
A property valuation and suitability checks
Consideration of the specific mortgage criteria for the property and borrower

If anything doesn’t meet the lender’s requirements at the full application stage, the outcome can change.

Is an Agreement in Principle the same as a mortgage offer?

No.

A mortgage offer is the formal stage where the lender agrees to lend under specific terms. An Agreement in Principle is an early indication and should be treated as a starting point, not the finish line.

What can go wrong?

Most issues come down to mismatches between what was provided at the early stage and what is later verified.

Potential reasons an Agreement in Principle may not translate into a full mortgage offer include:

Changes in your circumstances (income, spending, or commitments)
Information that can’t be verified as expected
The property not meeting the lender’s requirements after valuation
The lender’s criteria being more specific once the full application is assessed

Keeping your details accurate and up to date can reduce avoidable problems.

How a broker can help at this stage

A mortgage broker can help you understand how an Agreement in Principle fits into the wider process and how your situation may be viewed by lenders.

That can be particularly valuable if you:

Have complex income (for example self-employment)
Have existing credit commitments
Are buying with a partner and want to understand how affordability is assessed
Want to reduce uncertainty before making an offer

Key takeaways

An Agreement in Principle is an early indication of borrowing capacity, not a mortgage offer
It’s usually based on information you provide at the start of the process
It typically lasts 30–90 days, depending on the lender
Applying may involve a credit check, which could be hard or soft depending on the process
A full mortgage application can still be declined if circumstances or criteria don’t align

If you’re preparing to buy, understanding what an Agreement in Principle does—and what it doesn’t—can help you move forward with clearer expectations.