# What is a mortgage in principle, and when should you get one?

> A mortgage in principle is a lender saying roughly how much it might lend you, based on a quick look at your income and credit. It isn't a promise to lend, but agents like to see one before they take your offer seriously.

Mortgages · Published 2026-10-04 · Updated 2026-10-04 · https://firstkey.uk/articles/mortgage-in-principle

## What it is

Also called an agreement in principle or a decision in principle, it's a certificate from a lender with a figure on it. To get one you give your income, outgoings and address history, and the lender checks your credit file.

## What it isn't

It isn't a mortgage offer. The full application comes after your offer on a home is accepted, with payslips, bank statements and a valuation of the home. The lender can still say no, or lend less, at that stage.

## When to get one

- When you're ready to view seriously. It tells you a realistic budget before you fall for a home you can't reach.
- Before you make an offer. Many agents ask for it, and it makes you look ready to the seller.
- Not months too early. Most last 30 to 90 days, depending on the lender, so time it for when you're actively looking.

**Will it hurt my credit score?.** Most lenders use a soft search for a mortgage in principle, which other lenders can't see and which doesn't affect your score. Some use a hard search, so ask first, and don't apply to lots of lenders at once.

## What you'll need

- Your income, and any regular bonuses or overtime.
- Your regular outgoings, like loans, cards and childcare.
- Your addresses for the last three years.
- How much deposit you have, and where it's from.

As a rough guide, many lenders lend around 4.5 times your income. A mortgage broker can find the lenders most likely to say yes, and many charge first-time buyers nothing.

[Get your documents ready](https://firstkey.uk/guide/mortgage-ready): A checklist of everything lenders ask for, to tick off on your phone.

[What can you afford on your salary?](https://firstkey.uk/guide/afford): See the price your income and deposit could reach.

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