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2026-09-29 · 6 min read

How Do Banks Work Out Mortgage Affordability? (UK)

How UK banks work out mortgage affordability: verified income, committed spend, stress rates, and the affordability score behind the decision.

UK affordability is simple subtraction. Verified monthly income minus committed spend. The remainder must cover the stressed payment.

Banks verify income from credits, not payslips alone. Salary, gig, and self-employed credits get grouped by payer. Irregular pay gets averaged down, not up.

Committed spend hides in statements. Loans, cards, childcare, subscriptions, BNPL instalments. Standing orders to savings do not help. They stop after completion.

Then comes the stress test. Your payment is recalculated 2-3 points above the deal rate. Add credit-card minimums at stressed levels. The affordability score is that buffer expressed as a number.

Clean three months before applying. No gambling lines. No returned debits. No payday top-ups. Run statements through a bank statement analyser once to see the same ratios first.

FAQ

How do banks work out mortgage affordability in the UK?
They subtract verified committed spend from verified income, then test the remainder against the mortgage payment at a higher stressed rate.
What is an affordability score in UK banking?
A number summarizing income stability, committed spend, and buffer after a stressed mortgage payment. Higher buffer means higher score.

Now try it on a real statement

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How Do Banks Work Out Mortgage Affordability? (UK) — Bank Statement Analyser