How lenders decide on a mortgage
A lender decides on a mortgage using four ingredients: an automated credit score, an affordability assessment stressed at a higher interest rate, its lending criteria, and a valuation of the property. It combines them into a yes, a no, or a lower amount. Because lenders weigh these differently and set different thresholds, the same case can pass at one lender and fail at another, which is why the choice of lender is so important.
The four ingredients
- Credit score: an automated read of your credit history. High-street lenders rely on it heavily; specialist lenders take a more manual view.
- Affordability: can you afford the payments, tested at a stressed interest rate above the pay rate, alongside your outgoings.
- Criteria: the lender's rules on income type, employment, deposit, property and more. See the Lender Criteria Index.
- The property: a valuation and a check that the property is acceptable security.
Why the stress test exists
Lenders do not just check you can afford today's payment; they check you could cope if rates rose. With the Bank of England base rate at 3.75%[Bank of England], the stressed rate a lender uses is typically higher again, which is what caps how much it will lend. Because each lender chooses its own stressed rate and spending assumptions, two lenders can offer noticeably different maximum loans on the very same income.
How they combine into a decision
A strong case clears all four comfortably. A weakness in one can sometimes be offset by strength in another (a larger deposit, for example, can ease an affordability or credit concern), or it can be the thing that stops the application. Automated systems tend to decline when a case sits outside the standard mould, which is exactly when a lender that assesses cases more manually, found through a broker, can reach a different answer.
Common questions
What is a credit scorecard?
It is an automated score a lender gives your application based on your credit history and details. High-street lenders lean heavily on it for speed, so a marker on your file, or a thin credit history, can trigger a decline even when you could afford the mortgage. Specialist lenders tend to take a more manual view.
What is the affordability stress test?
Lenders check you could still afford the mortgage if interest rates were higher than the pay rate. They apply a stressed rate to your income and outgoings. Because lenders use different stressed rates and assumptions, the maximum they will lend varies a lot between them.
Why does the property matter?
The lender lends against the property as much as against you. It values the property and checks it is acceptable security. Construction type, a short lease, a flat above commercial premises, or a valuation coming in low can all affect or stop a decision, regardless of how strong you are as a borrower.
Do all lenders decide the same way?
No. They use the same broad ingredients, credit, affordability, criteria and the property, but weigh them differently and set different thresholds. That is the single most important thing to understand: a decline is usually a mismatch with one lender, not a verdict from the whole market.
Back to the mortgage readiness hub. Worried about the answer? See will I be accepted and how to improve your chances.
Founder, MortgageExplained, MortgageExplained
Adam spent nearly a decade as a mortgage adviser at Just Mortgages, with further experience in commercial finance. He is CeMAP and CF qualified. He built MortgageExplained to do one thing well: explain mortgages in plain English, then introduce you to a regulated broker when you are ready. Every page is written and reviewed by Adam.
Last reviewed: 21 July 2026