The short answer
How much you can borrow depends on the lender’s assessment of your circumstances. An income multiple does not tell you exactly how much you can borrow. It is, at most, an initial indication. A lender’s assessment may also consider verified income, committed spending, household dependants, the mortgage term, repayment basis, credit file, deposit and property, affordability under its own stress and criteria, and the evidence supplied. Lenders do not all use the same formula, and an indication is not an offer or a decision in principle.
Borrow only an amount that remains affordable if circumstances change. A regulated mortgage adviser or lender can assess the complete application; this guide is general information, not a recommendation or offer.
What an affordability assessment may consider
Income, and how it is evidenced
A lender may consider salary, regular contractual pay and eligible variable income, subject to its criteria and evidence. It may distinguish between basic pay, overtime, bonus, commission and other income rather than simply adding every figure on a payslip. An employed applicant may be asked for payslips, bank statements, a P60 or an employer letter.
For self-employed applicants, the lender may review accounts, tax calculations and tax-year overviews (often requested through HMRC records), business circumstances and the continuity or sustainability of income. Requirements and treatment vary: do not assume every lender uses the same number of years, averaging method or approach to retained profit, dividends, director income or recent changes. See self-employed mortgages in Scotland for related context.
Committed spending and regular costs
Credit commitments, loans, car finance, credit-card payments, maintenance, childcare, insurance, council tax, utilities and other regular outgoings can reduce disposable income. A lender may ask about commitments that will continue after completion and may assess declared spending alongside information from bank statements and the credit application. Do not omit a payment because an income multiple appears to leave room.
Dependants and household circumstances
Children and other dependants can affect the household budget. The number and ages of dependants, childcare and maintenance arrangements may matter, as may a second applicant’s income and commitments. A joint application is not simply one income multiple multiplied by two: the lender assesses the whole household and the application’s risks.
Term, repayment basis and rate assumptions
A longer term can reduce the scheduled monthly payment but can increase total interest and may interact with age, retirement plans and lender policy. A repayment mortgage is assessed differently from an interest-only application, which has additional eligibility and repayment-plan considerations. A fixed rate does not make a mortgage permanently affordable after the deal period. The lender’s assumed rate, affordability test and stress approach are its own; this guide does not state a universal stress rate or formula.
Credit file, deposit and property
Credit history, current applications, missed payments, insolvency markers and the accuracy of electoral-register and account information can affect eligibility and the lender’s assessment. A credit score is not a universal pass mark. Read more about credit files and mortgage applications.
The deposit affects the loan-to-value (LTV) and the property price a given loan could support, but a larger deposit does not guarantee that the affordability assessment will pass. The lender will also consider the property, valuation, construction and its lending policy.
Why an income multiple is not an offer
For illustration, £40,000 of income multiplied by an example factor of 4.5 produces £180,000. That arithmetic is not a lender quote, maximum, decision in principle or promise. It ignores the other inputs above, the proposed term and repayment basis, the deposit and LTV, the property and the lender’s current criteria. Do not publish a “most people can borrow X times income” statement as a universal rule.
An agreement in principle is also not a guaranteed mortgage offer. It can be based on limited information and remains subject to full application, evidence, valuation and lender checks. Ask what information was used and what remains outstanding.
Illustrative household scenarios
These are hypothetical comparisons, not calculated borrowing promises. They deliberately do not provide a borrowing figure, rate, affordability score or lender result. The changed input is the point.
Scenario A — Same income, new committed spending
Two employed applicants have the same verified household income in both versions. In Version 1 they have no car finance; in Version 2 a monthly car-finance commitment starts before application. The lender may have less disposable income to assess in Version 2, so the outcome could change even though income has not. The applicants should disclose the commitment and provide the requested statements.
Scenario B — Same income, different dependants and childcare
One applicant has the same salary in both versions. Version 1 has no dependants; Version 2 includes a child and regular childcare costs. A lender may assess different household expenditure and affordability. This is not a reason to understate dependants or costs.
Scenario C — Same headline profit, different evidence
Two self-employed applications show the same latest-year headline profit. In Version 1, accounts and tax evidence are complete and income is consistent; in Version 2, income has recently changed and evidence is incomplete. Lenders may ask different questions or apply different criteria. Neither scenario implies an approval or a universal treatment of self-employed income.
Documents checklist
Prepare documents only as requested and redact account numbers when sharing copies informally:
- proof of identity and address;
- recent payslips, P60 and bank statements for employed applicants;
- employment contract or employer confirmation where requested;
- bonus, commission, overtime or other variable-income evidence;
- self-employed accounts, tax calculations and tax-year overviews, plus business or company information where requested;
- evidence for pensions, benefits, maintenance or other income the lender agrees to consider;
- statements or settlement details for loans, credit cards, hire purchase and other commitments;
- childcare, maintenance, school-fee and regular household-cost information;
- deposit evidence, including gifted-deposit declarations and the donor’s evidence where required;
- details of the proposed property, Home Report/valuation and buildings insurance when requested;
- explanations and documents for credit-file discrepancies, missed payments or address history.
Requirements vary by lender and case. Do not send sensitive documents by an unverified channel.
Practical next steps
- Record gross income by type, monthly committed spending, dependants and deposit; do not round away material costs.
- Check your credit reports for errors before making multiple applications; see credit files and mortgage applications.
- Gather evidence for the income type rather than relying on an online multiple.
- Compare a sustainable term and repayment basis, including what happens when a fixed period ends.
- Read mortgage deposits in Scotland and consider how deposit and LTV affect the purchase budget.
- For self-employed cases, read self-employed mortgages in Scotland.
- When you are ready, discuss your mortgage options. The adviser or lender should explain what is indicative, what is evidenced and what remains subject to underwriting.