Mortgage in Principle: What it is and Why You Need One Before You Start House Hunting

A mortgage in principle (sometimes called an agreement in principle or AIP) is a document from a lender confirming that, based on the information you have provided, they would, in principle, be willing to lend you a certain amount.

It is not a formal mortgage offer. It is not a guarantee. It is a statement of intent, based on a quick financial check, that tells you roughly how much you could borrow.

Estate agents will often ask to see a mortgage in principle before they will book you in for viewings.

It signals that you are a serious buyer rather than someone who is browsing without any means to follow through.

When you make an offer on a property, having a mortgage in principle strengthens your position.

Sellers, especially those with multiple offers, are more likely to accept from a buyer who has already done the groundwork.

Most lenders run a soft search when issuing a mortgage in principle.

A soft search is not visible to other lenders and does not affect your credit score. You can get one without any negative consequences.

Check before you apply, as a small number of lenders use a hard search at this stage. A broker will know which is which.

Most mortgage in principle documents are valid for 60 to 90 days.

If yours expires before you find a property, you can renew it. The process is the same as applying in the first place.

No. A mortgage in principle is based on the information you provide upfront.

The formal mortgage application involves full verification of your income, outgoings, credit history, and the property itself.

A lender can still decline you at the full application stage, though if your mortgage in principle was based on accurate information, this is unlikely.

You can apply directly to a lender through their website, which takes around 15 minutes. You will need your income, monthly outgoings, and basic employment information.

Alternatively, a broker can get one for you.

A broker has access to the whole market and can identify which lenders are most likely to approve a full application based on your circumstances. For first-time buyers, this is usually the better approach.

This depends on your income, outgoings, deposit size, and the lender’s own affordability criteria. Most lenders offer between 4 and 4.5 times your annual salary, though this varies. Use our Mortgage Calculator to get an estimate before you apply.

Sources: MoneyHelper, FCA consumer guidance. This article is for information only and does not constitute financial advice.