Agreement in Principle (AIP) Explained: UK Mortgage Guide 2026

What Buyers Should Know About an Agreement in Principle

By WIS Team

March 13, 2026

3 minutes read

TLDR

When buying a property, many buyers hear the terms Agreement in Principle (AIP), Decision in Principle (DIP) or Mortgage Pre-Approval. These terms refer to an early stage in the mortgage process where lenders indicate how much they may be willing to lend. Having an Agreement in Principle can give buyers more confidence when searching for a property and may also help demonstrate financial readiness to estate agents.

Key Point

Key Point	Summary
What an AIP is	An early indication of how much a lender may be willing to lend
Not a guarantee	It does not guarantee a mortgage approval
Helps buyers	Can strengthen offers when buying a property
Usually, quick	Often arranged within a short time once basic details are provided
Credit search	Usually, Soft

What Is an Agreement in Principle?

An Agreement in Principle is based on basic financial information provided to a lender.
This typically includes:

income details
employment information
credit history
deposit amount

Based on this information, the lender may provide an estimate of how much they could potentially lend.

Agreement in Principle vs Mortgage Application

An AIP is simply an early step in the process and does not replace a full mortgage application.

Stage	What Happens
Agreement in Principle	Initial affordability indication
Mortgage Application	Full financial documents reviewed
Mortgage Offer	Formal approval issued by the lender

Why Buyers Obtain an AIP

Benefit	Explanation
Budget clarity	Helps buyers understand potential borrowing
Stronger offers	Estate agents often prefer buyers with an AIP
Faster purchase process	Buyers can move more quickly when they find a property

Common Mistakes Buyers Make

Mistake	Why It Matters
Assuming an AIP guarantees approval	Full checks still take place
Not checking credit reports	Issues may affect the full application
Waiting until after finding a property	Can delay the purchase process

Real Life Example

A buyer based in Kent recently obtained an Agreement in Principle before starting their property search. When they found a suitable home, the estate agent was more confident accepting their offer because they already had an indication from a lender. Having the AIP in place helped move the process forward more smoothly.

Helping Homebuyers Across the UK

At WIS Mortgages, we help buyers across England, Wales and Scotland understand the mortgage process, including obtaining an Agreement in Principle before beginning their property search.

FAQs

1. Does an Agreement in Principle guarantee a mortgage?

No. It is an initial indication only. Full checks are carried out during the application process.

2. How long does an AIP last?

Many lenders issue AIPs that remain valid for around 60 to 90 days.

3. Does getting an AIP affect my credit score?

Some lenders perform soft checks while others may carry out full credit checks.

4. Do estate agents require an AIP?

Some estate agents prefer buyers to have one before accepting an offer.

5. What happens after obtaining an AIP?

Once a property is chosen, you proceed to a full mortgage application.

FCA Disclaimer

Your home may be repossessed if you do not keep up repayments on your mortgage.
This article is for general information only and does not constitute personalised advice.