Find out how much you could borrow for a UK mortgage based on your income, outgoings and deposit — including a stress test at 3% above your deal rate, which all UK lenders are required to apply.
How mortgage affordability is calculated in the UK
UK lenders use two main tests to determine how much they’ll lend: an income multiple (typically 4–5.5× your gross annual income) and a detailed affordability assessment that looks at your monthly commitments and disposable income after essential spending.
The income multiple gives you a headline figure — but lenders then stress-test it. The FCA requires lenders to check you could still afford repayments if the interest rate rose by 3 percentage points above your deal rate. If the stressed payment would be unaffordable given your outgoings, the lender will reduce the offer.
Key 2025/26 Affordability Rules
Most high street lenders: 4–4.5× income · Specialist/professional lenders: up to 5.5× · Stress test: current rate +3% · Max LTV (residential): 95% · Joint applications: combined income used
What reduces how much you can borrow?
Lenders reduce their offer when they see existing commitments eating into your disposable income. The main factors that cut borrowing power are:
- Existing debt repayments — car finance, personal loans, credit card minimums. A £400/month car payment can reduce borrowing by £40,000–£60,000.
- Childcare costs — counted as a fixed monthly commitment in affordability models.
- Number of dependants — lenders apply standard living cost allowances per dependent child.
- Credit score — a poor score may push you toward higher-rate products, which increases the stressed monthly payment, which reduces the loan offer.
- Employment type — self-employed applicants typically need 2–3 years of accounts; day-rate contractors may be assessed differently by specialist lenders.
Joint mortgage vs sole application
A joint mortgage uses both applicants’ combined income for the income multiple calculation, which is the primary reason couples can usually borrow significantly more than a single buyer. Lenders treat all applicants’ debts and outgoings in the assessment — so a partner with high existing debt can actually reduce overall borrowing capacity compared to a sole application.
The key is to optimise before applying: paying down credit card balances and car finance before a mortgage application can meaningfully increase what you’re offered.
Frequently asked questions
What income multiple will I get?
It varies by lender and your circumstances. Most high street banks offer 4–4.5× as a starting point. Many mainstream lenders now offer 5× for borrowers with clean credit and a reasonable deposit. Professional mortgage schemes (for doctors, dentists, solicitors, accountants) routinely lend at 5–5.5×. The best way to find the actual maximum for your situation is to use a whole-of-market broker, as they can identify which lenders will give the most generous multiple for your specific income structure.
Does my deposit affect how much I can borrow?
Your deposit directly determines your LTV ratio, which affects the interest rate you’re offered. A better rate means lower monthly payments, which means you pass the stress test more comfortably, which can allow lenders to offer slightly more. However, deposit size doesn’t directly multiply borrowing capacity — the income multiple is the primary driver. The main value of a larger deposit is accessing better rates and avoiding higher LTV surcharges.
Can I borrow more than 4.5× my salary?
Yes — many lenders now offer 5× and some will lend 5.5× to applicants with strong profiles. The FCA removed the hard 4.5× cap restriction, leaving it to lenders to determine their own policies within responsible lending rules. Specialist lenders, building societies, and professional mortgage schemes are more likely to lend at higher multiples. A broker who knows the market can identify which lenders are most generous for your income level, job type, and LTV.
What is a Decision in Principle (DIP)?
A Decision in Principle (also called Agreement in Principle or mortgage in principle) is a conditional indication from a lender of how much they would lend you, subject to a full application and valuation. It involves a soft or hard credit check depending on the lender, and typically valid for 30–90 days. Estate agents often ask to see one before accepting an offer on a property, as it demonstrates you have borrowing confirmed. Getting a DIP before viewing properties helps you focus on realistically affordable homes.
How does the Help to Buy / Mortgage Guarantee Scheme work?
The original Help to Buy equity loan scheme closed in March 2023. The Mortgage Guarantee Scheme, which allows lenders to offer 95% LTV mortgages with a government guarantee on the higher-risk portion, was extended to June 2025. From mid-2025, the main route for low-deposit buyers is the standard 95% LTV market, which several lenders participate in without any government scheme. First-time buyers should also consider the Lifetime ISA, which provides a 25% government bonus on up to £4,000 per year saved toward a first home purchase.
