How much can you really borrow?
"Affordability" is the single biggest factor in whether your offer gets accepted. UK lenders no longer just multiply your salary, they model your whole financial life. This guide explains exactly how the assessment works in 2025/26, what moves the number, and how to maximise it.
Income multiples, the starting point
Most lenders cap borrowing at a loan-to-income (LTI) multiple, typically around 4.5 times your gross annual income, occasionally 5 to 5.5 times for higher earners, professionals or specific schemes. On a £45,000 income, 4.5× gives a £202,500 ceiling. With a joint application the incomes are combined, which is why two average salaries often out-borrow one large one. Lenders are also limited by regulation in how many loans they can write above 4.5× LTI, so that band can tighten late in the year.
LTI is a cap, not a promise
Affordability modelling and committed outgoings
Since the post-2014 mortgage rules, lenders run a detailed affordability assessment: net income minus committed and essential expenditure must comfortably cover the mortgage. Car finance, personal loans, credit-card balances, childcare and school fees all reduce your capacity. As a rule of thumb, every £100/month of commitment can cut your maximum borrowing by several thousand pounds, because that £100 could otherwise have serviced part of a larger loan. Clearing or reducing short-term debt before you apply is often the fastest way to lift your budget.
The stress test
Lenders check you could still afford the mortgage if rates rose. Until 2022 the Bank of England required a stress of roughly 3% above the reversion rate; that specific rule was withdrawn, but lenders still apply their own stress (commonly +1% to +3%, or a floor rate). The calculator above lets you set the uplift to see how a higher rate squeezes affordability. A payment that looks fine today but fails at a stressed rate is exactly what the test is designed to catch.
What actually counts as income
Basic salary is counted in full. Variable pay is treated cautiously: many lenders count only 50 to 100% of a regular bonus, overtime or commission, and want a track record (often two years). The self-employed are usually assessed on the average of the last two to three years' profits or salary-plus-dividends. Benefits such as Child Benefit and tax credits may be partially counted. Because policies vary widely, two lenders can offer very different amounts on identical paperwork, which is where a broker earns their fee.
| Income type | Typical treatment |
|---|---|
| Basic salary | 100% |
| Regular bonus / commission | 50 to 100%, with history |
| Overtime / shift allowance | 50 to 100% |
| Self-employed profit | 2 to 3 year average |
| Benefits (e.g. Child Benefit) | Often partially counted |
Deposit, LTV and the rate you'll get
Your deposit sets your loan-to-value (LTV), and LTV largely sets your interest rate. The bands matter: crossing from 90% to 85%, or 80% to 75%, can unlock a noticeably cheaper rate, which in turn improves affordability. A bigger deposit therefore helps twice, it reduces the loan and lowers the rate on it. Below 60% LTV the rate benefit flattens. Don't forget the deposit isn't your only upfront cost: stamp duty, legal fees and surveys all need separate cash.
A couple earning £70,000 combined
Two applicants earning £45,000 and £25,000 have a combined income of £70,000. At 4.5× that's a £315,000 LTI ceiling. With £350/month of car finance and credit commitments, affordability modelling trims roughly £55,000 of capacity, bringing the realistic maximum loan to around £260,000. Adding a £40,000 deposit gives a property budget near £300,000 at about 87% LTV. Pay off the car finance first and the budget can jump by tens of thousands, the calculator above shows the effect instantly.
How to increase what you can borrow
- Clear short-term debt. Paying off loans and card balances frees up affordability quickly, often more than a small pay rise would.
- Extend the term. A longer term lowers the monthly payment and can raise the maximum loan, at the cost of more total interest.
- Add a co-applicant. A second income (or a joint-borrower-sole-proprietor arrangement) can lift the ceiling substantially.
- Grow the deposit. A larger deposit cuts LTV, unlocks a cheaper rate and improves affordability.
- Use a broker. Lender policies differ enormously on bonuses, self-employment and multiples. A broker finds the most generous fit.
Common mistakes
- Confusing a multiple with an offer. A 4.5× figure is a ceiling. Affordability, credit and the stress test decide the real number.
- Forgetting upfront costs. Your deposit, stamp duty, legal fees and survey are separate cash needs, don't spend it all on the deposit.
- Applying with avoidable debt. Even unused credit-card limits and recent searches can dent affordability. Tidy your file first.
- Maxing out the budget. Borrowing the absolute maximum leaves no room for rate rises or life changes. Build in headroom.