A Mortgage in Principle is the first real step towards buying — a lender's early indication of what it might lend you. It's not a guarantee, but it tells sellers you're serious and shows you a realistic budget. Here's what it is, how to get one, and what it does (and doesn't) mean.
The short answer
A Mortgage in Principle — also called an Agreement in Principle (AIP) or Decision in Principle (DIP) — is a statement from a lender indicating how much it might be willing to lend you, based on a quick check of your income and credit. It gives you a realistic budget before you start viewing.
Estate agents often ask for an AIP before they'll take your offer seriously, because it shows you can likely fund the purchase. It also stops you falling for homes outside your budget. Pair it with our how much can I borrow guide and affordability tools to house-hunt with confidence.
It depends on the lender. Some run a 'soft' check that doesn't affect your score; others run a 'hard' check that leaves a footprint. Always ask which type it is before applying, and avoid making lots of hard-check applications in a short space of time.
Crucially, an AIP is not a commitment to lend. The full application still involves detailed checks, a property valuation and underwriting, and can come back with a different figure — or a decline. Treat it as a strong indication, not a done deal.
You can get an AIP directly from a lender or through a mortgage broker, usually online and often within minutes to a day. A broker can help you approach a lender likely to accept you, which matters if your circumstances are less standard — see our self-employed and bad credit guides, and the pillar UK Mortgage Guide.
It's a lender's early indication of how much it might be willing to lend you, based on a quick check of your income and credit. It is also called an Agreement in Principle (AIP) or Decision in Principle (DIP).
It can. Some lenders use a soft credit check that doesn't affect your score, while others use a hard check that leaves a footprint. Ask which type the lender uses before applying.
Typically around 30 to 90 days, depending on the lender. If it expires before you find a home, you can usually renew it.
No. It's an indication only. The full mortgage application involves detailed checks and a property valuation, and the final decision or amount can differ.