A decision in principle is a lender's non binding statement of how much it would likely lend, based on stated income, outgoings and a credit check. It takes 5 to 15 minutes online, lasts 30 to 90 days depending on the lender, uses a soft credit search at most lenders, and converts to full approval roughly 90 to 95% of the time when the stated information holds.
TL;DR · LAST REVIEWED 25 JULY 2026
- DIP, AIP and mortgage in principle are the same product under different lender branding
- Validity runs 30 to 90 days by lender, with 90 the most common window; renewal takes minutes
- Most lenders use soft credit searches that leave no footprint; a minority still run hard checks
- It is not underwritten: documents, valuation and full checks come at application, which takes 2 to 6 weeks to offer
- New credit, an income drop, missed payments or a lender recalibrating affordability can invalidate a DIP before its printed date
KEY FACTS
- Time to obtain: typically 5 to 15 minutes online with income, outgoings and address history to hand
- Validity: 30 to 90 days depending on lender; 90 days is the most common, some issue for 60
- Credit check: soft search at most lenders, invisible to other lenders and harmless to scores
- Conversion: roughly 90 to 95% of DIPs from major lenders proceed to full approval on accurate information
- Full mortgage offer follows complete underwriting and valuation, typically 2 to 6 weeks into application
- Many agents expect a DIP plus proof of deposit before treating an offer as proceedable
What a DIP is, and is not
The DIP answers one question early: how much will a lender plausibly advance. It is not underwritten: no documents are verified and no property is valued, so the lender can still decline the full application if verification or valuation surfaces something the quick check missed.
What it does deliver is a real budget for the house hunt and credibility with sellers and agents, many of whom expect one alongside proof of deposit before progressing an offer. The full mortgage offer, issued after complete underwriting, is the binding document.
Validity, and what breaks it early
Validity runs 30 to 90 days by lender. A DIP can also effectively expire early: taking out new credit, a drop in income, missed payments, or the lender retuning its affordability calculator can all invalidate the figure before the printed date.
The practical habit is refreshing the DIP just before an offer goes in whenever anything has changed or the document is old. A refreshed application takes minutes, and rate movements between issue and application can revise the figure in either direction.
Getting one well
The inputs are income, regular outgoings, existing credit commitments, address history and deposit source. Applying through a broker produces a DIP from a lender matched to the borrower's profile, which matters most at the margins: self employment, recent credit events, unusual income.
Multiple DIPs from different lenders are harmless when soft searched; a string of hard searched applications in a short window is the pattern to avoid. Self employed applicants receive DIPs on stated figures, with verification against accounts and tax records at full application.
Getting a decision in principle
- Gather income figures, regular outgoings, three years of address history and deposit source
- Confirm the lender or broker uses a soft credit search before applying
- Complete the online application; a digital decision typically arrives in 5 to 15 minutes
- Note the expiry date and the assumptions the figure rests on
- Refresh the DIP before making an offer if circumstances change or the document ages past its window
RELATED GUIDES
DISCLAIMER
This article is editorial information, not financial advice. Kael Tripton Ltd is not authorised or regulated by the Financial Conduct Authority. Figures were correct at the last review date shown above; verify current rates and rules with the primary sources listed below before acting.
Frequently asked questions
How long does a mortgage in principle last?
Between 30 and 90 days depending on the lender, with 90 days the most common. Renewal takes minutes if the search runs longer, and a refresh is sensible whenever circumstances change.
Does a decision in principle affect my credit score?
Not at lenders using soft searches, which is most of the market. A minority still run hard checks, so confirming the search type first is worth thirty seconds.
Is a DIP a guarantee of a mortgage?
No. It is non binding and pre underwriting. On accurate stated information roughly 90 to 95% of DIPs from major lenders convert, but verification, valuation or changed circumstances can end differently.
Do I need one to make an offer?
Not legally, but many agents and sellers expect a DIP plus proof of deposit before treating an offer as proceedable.
What is the difference between a DIP and a mortgage offer?
The DIP is a quick unverified indication. The offer is the binding document issued after full underwriting and valuation, typically 2 to 6 weeks into the application.
Are AIP, DIP and mortgage in principle different?
No. Agreement in principle, decision in principle and mortgage in principle are the same product under different branding.
SOURCES
- FCA: Mortgages – accessed 25 July 2026
- GOV.UK: Housing and local services – accessed 25 July 2026
