The short answer
A Mortgage in Principle, Decision in Principle and Agreement in Principle usually describe the same early step: a lender estimates what it might lend using limited financial information and, often, a credit check. It is not a binding mortgage offer and can change after full affordability, document, fraud-prevention and property checks.
Why buyers get one
It can give a more realistic search budget and show an estate agent that a buyer has begun arranging finance. It is not legally required to view or offer on a home, and showing the maximum figure does not mean that amount is comfortable to borrow.
What you may be asked for
- identity, date of birth and address history;
- income and employment details;
- regular spending, debts and financial commitments;
- deposit amount and sometimes its source;
- the intended property price or borrowing amount.
Ask whether the credit check is soft or hard
A soft search is not normally visible to other lenders as an application. A hard search is recorded on the credit file and can be seen by lenders. Policies differ, so ask before submitting repeated applications.
Why the final offer can be different
The lender still needs supporting documents, a full affordability decision and an acceptable valuation and property. Changed income, new borrowing, inaccurate information, construction concerns, lease issues or a lower valuation can reduce the loan or lead to refusal.
Validity and timing
MoneyHelper says an Agreement in Principle is typically valid for 30 to 90 days, but the lender’s own expiry controls. Avoid obtaining several too early merely to collect maximum figures. Update the lender or adviser if your circumstances change.
Plan a budget before requesting the maximum
Use the buying-power calculator and mortgage calculator to set your own price and payment boundaries before treating a lender estimate as a target.
Sources and limitations
Read MoneyHelper’s current Mortgage in Principle guide and application guidance. Processes differ by lender. Send corrections to hello@propertiesandhomes.co.uk.
Reviewed by the Properties & Homes editorial team
Published and last reviewed: 14 August 2026.
Change log: first edition.