How much can I afford to borrow for a mortgage?

Before you start viewing properties, it’s worth getting a clear sense of your likely mortgage borrowing limit. Lenders don’t base affordability on income alone. They also look at your existing financial commitments and whether the repayments are likely to remain manageable as your circumstances change.

This guide explains how borrowing limits are typically assessed, what influences the maximum you can borrow, and what to consider if you’re self-employed.

How lenders assess your mortgage borrowing limit

Mortgage borrowing capacity is usually worked out in two stages:

1. Income check – what you earn and how reliably you earn it.
2. Affordability assessment – whether the proposed repayments fit comfortably alongside your monthly outgoings and other commitments.

Even if you have a high income, your maximum borrowing can be reduced if your regular spending and debts leave limited “headroom” for mortgage payments.

What lenders look at: income and stability

Lenders typically consider several types of income, but the way they treat each one can vary.

Common income sources

• Salary (including overtime, where it’s consistent and can be evidenced)
• Bonuses (often only where there’s a clear history)
• Dividends (for some applicants, subject to evidence)
• Benefits (where relevant)
• Rental income (in some cases, depending on the mortgage type and how it’s evidenced)

Why stability matters

It’s not just about the amount of income. Lenders also want to understand whether it looks sustainable. Income that’s irregular, newly started, or difficult to verify may be treated more cautiously.

What lenders look at: monthly outgoings and commitments

Affordability is heavily influenced by your existing financial commitments.

Typical outgoings included in affordability

Lenders may take account of:

• Credit card repayments
• Personal loan and car finance payments
• Child maintenance payments
• Household spending and other day-to-day costs (as assessed through affordability calculations)
• Other regular commitments

A useful way to think about this is debt-to-income: the proportion of your income that goes on debt repayments and essential commitments. The higher your outgoings relative to your income, the more likely your borrowing limit will be lower.

How deposit size and LTV can affect what you can borrow

Your deposit is the cash you put towards the purchase price. The loan-to-value (LTV) is the mortgage amount expressed as a percentage of the property value.

Why LTV matters

In general terms:

• Lower LTV (larger deposit) can make the mortgage appear less risky.
• Higher LTV (smaller deposit) can reduce the maximum borrowing or lead to stricter conditions.

Even where deposit doesn’t directly change your income, it can affect the overall mortgage structure and what lenders are willing to offer.

Example: visualising LTV

If a property costs £250,000:

• A £25,000 deposit is 10% → mortgage is £225,000 → LTV is 90%
• A £50,000 deposit is 20% → mortgage is £200,000 → LTV is 80%

How much can you borrow based on income multiples?

Many people start by using an income multiple rule of thumb. In practice, lenders usually apply affordability calculations rather than relying on a single multiplier.

That said, it’s common to see lenders consider borrowing in the region of around 4 to 4.5 times annual income for many applicants, depending on circumstances.

Your likely maximum can move up or down based on factors such as:

• Your monthly outgoings and existing debts
• The mortgage term you’re aiming for
• Your credit history
• Whether you’re applying alone or jointly
• The type of mortgage product
• Your household situation and dependants

Why the mortgage term can change affordability

The term affects monthly repayments. A longer term can reduce the monthly payment (which may help affordability), but it can increase the total interest paid over the life of the mortgage.

Mortgage affordability calculators: helpful, but not definitive

Affordability calculators can be a useful starting point. They typically use inputs such as:

• Income
• Monthly outgoings
• Deposit
• Mortgage term

However, calculators can’t fully replicate how different lenders treat items like overtime, bonuses, childcare costs, or other commitments. They’re best used to estimate a range, then refine your understanding with a more tailored assessment.

Can you borrow more with a smaller deposit?

A smaller deposit usually means a higher LTV, which can make borrowing more difficult. Some buyers explore alternatives that change the structure of the purchase.

Options that may be considered in certain circumstances include:

• Shared Ownership (buying a share and paying rent on the remainder)
• Government-backed schemes (where eligible)
• Guarantor arrangements (where available)

These routes can introduce additional costs (for example, rent and service charges in Shared Ownership), which still need to be included in budgeting and affordability.

Borrowing if you’re self-employed

Self-employed applicants often face a different evidence process because income can be more variable and may be structured differently.

How lenders may assess self-employed income

Depending on your circumstances, lenders may look at evidence such as:

• Tax year accounts
• HMRC documentation (for example, SA302s)
• Accountant-prepared reports
• Evidence showing trading history and income consistency

Sole traders and partnerships

Income is often assessed based on average profits over a relevant period, rather than a single year.

Limited company directors

For directors/shareholders, lenders may consider a combination of salary and other elements such as dividends or retained profits, depending on how the business finances are structured.

Practical steps to strengthen affordability evidence

• Keep accounts and tax returns accurate and up to date
• Ensure your income evidence clearly reflects your current position
• Consider whether you can increase your deposit to improve the overall application strength

Planning for interest rate changes and future costs

Affordability isn’t just about what your mortgage payment looks like today. If you’re not on a long fixed rate, payments can change when the deal ends.

When budgeting, it can help to:

• Consider how payments might look if interest rates were higher
• Think about likely changes to outgoings (for example, childcare, commuting, or household bills)
• Keep some savings available for unexpected expenses

What happens if a mortgage is declined for affordability?

If an application is declined due to affordability, it usually means the lender concluded that the proposed repayments would not be sufficiently manageable given the information provided.

Common reasons can include:

• Outgoings and commitments leaving limited disposable income
• Insufficient or inconsistent income evidence
• A mismatch between the amount you want to borrow and what the affordability assessment supports

In these situations, it’s often more productive to review what’s driving the affordability outcome and adjust the plan—such as the deposit, the property price, the mortgage term, or the way income is evidenced—before trying again.

Key takeaways

• Your borrowing limit depends on income and stability, but also outgoings and commitments.
• Deposit size and LTV can influence what lenders are willing to offer.
• Income multiples are a starting point, but affordability calculations are what usually determine the final outcome.
• If you’re self-employed, the quality and consistency of your evidence can be just as important as your income.
• Budget for potential changes in interest rates and future household costs.

Related topics to explore

• How mortgage repayments are calculated and what affects monthly payments
• What mortgage lenders look for in an application
• How income multiples work in practice

Important information

Mortgage lending decisions are based on individual circumstances and lender criteria. This guide is for general information and does not guarantee approval.