What is loan serviceability and how do lenders work it out?

What is loan serviceability?

Serviceability is the test a lender runs to decide whether you can afford a loan. It looks at the money you reliably bring in, the money you spend, the debts you already carry and the new repayments you are asking to take on. If there is comfortable room left over, you pass. If the margin is thin, the lender may reduce the amount, ask for changes or say no.

It is not a judgement of character. It is arithmetic with some policy layered on top, and the policy is where lenders differ. The same applicant can have very different borrowing power depending on who is doing the sums.

How do lenders work it out?

Most assessments follow the same broad steps:

1. Count income. Base salary is usually counted in full. Bonuses, overtime, commissions, rental income and self-employed profit are often shaded or averaged, depending on the lender.
2. Estimate living costs. Lenders compare what you declare with benchmarks and with the spending shown in your bank statements, then often use the higher figure.
3. Add commitments. Existing loan repayments, credit card limits, buy now pay later accounts, child support and HECS-HELP repayments are included.
4. Apply a buffer. The new loan is tested at a higher interest rate than the one you will actually pay.
5. Check the surplus. If your income covers everything with room to spare, the loan passes.

Responsible lending rules also require a lender to make reasonable inquiries and not lend where it would likely cause substantial hardship. Moneysmart makes the same point, noting lenders must decline a loan if the assessment shows it could cause hardship.

What is the serviceability buffer?

The buffer is an extra margin on the interest rate used in the test, so that a borrower is not approved on the assumption that rates and costs stay low forever. APRA, the prudential regulator, has set the mortgage serviceability buffer for authorised deposit-taking institutions at 3 per cent and has indicated it is keeping it there. Lenders that are not authorised deposit-taking institutions, such as many non-bank and private lenders, are not bound by that setting and may use their own approach.

We do not quote loan rates on this site, so the point here is the mechanism: your repayments are tested against a stricter scenario than the real one.

What is the debt-to-income limit?

APRA activated a debt-to-income limit effective from February 2026. In APRA’s description, loans with a debt-to-income ratio of six times or more are capped at 20 per cent of an institution’s new mortgage lending, measured quarterly and separately for owner-occupier and investor lending. It covers new lending by authorised deposit-taking institutions, not existing borrowers, and bridging loans for owner-occupiers and loans for new dwellings are exempt.

For most borrowers the practical effect is that banks may be more cautious with very high debt relative to income. It is one more reason that borrowers with large debts or complex structures sometimes look at non-bank home loans or other routes.

What reduces your borrowing power?

• Credit card limits. A large unused limit is still counted by many lenders. Our guide on how to improve your credit score covers tidying limits.
• Buy now pay later accounts. Lenders may consider them even where they are not reported (see BNPL and your credit score).
• Existing loans and car finance. These are fixed commitments.
• Dependants and higher living costs. Lenders factor in family size.
• Short or irregular income history. Contract, casual and self-employed income is often averaged or discounted.
• Overdue accounts or arrears. These suggest that the budget is already stretched.

How is self-employed or irregular income treated?

Lenders usually take an average of your income across the last one or two years rather than the best month, then discount for any decline. Business expenses, add-backs and one-off items can change the number significantly, which is why two lenders can come up with different incomes from the same tax return. The guide to how much you can borrow when self-employed goes into detail, and the page on self-employed home loans shows the loan side.

How can you lift your serviceability?

Some changes are practical and quick, others take time:

• Close or reduce unused credit limits.
• Pay down small debts that eat into your assessed repayments.
• Avoid new credit in the months before applying.
• Show consistent savings in your account.
• Add a second income or a guarantor where that suits the family. The guarantor guide explains the risks first.
• Choose a longer loan term or interest-only structure where appropriate; see interest-only vs principal and interest.
• Use the loan calculator to see how different structures change repayments.

Where a bank result is too tight, structures like a debt consolidation loan can sometimes reduce monthly commitments by combining several debts. That is general information, not personal advice, and it depends on your circumstances.

Do private lenders assess serviceability differently?

They can. Private lenders often place more weight on the security and the exit strategy than on a conventional income test, particularly for short-term loans. That does not mean affordability is ignored. Most responsible lenders still want to know how interest will be paid and how the loan will end. Ownright’s page on difficult home loans covers situations where a bank test is the problem, and how private lenders assess your loan explains the alternative approach.

How does Ownright help?

Ownright is about solutions. Trevor Scott has 40-plus years in finance, and the team arranges loans Australia-wide. When a serviceability result from one lender is disappointing, we look at other lenders whose policies count your income differently, or at structures that fit your situation better. Because every lender sets its own rules, a no from one is not a no from all.

An illustrative example: a couple with two large unused credit card limits are assessed as borrowing less than they hoped. A broker may suggest reducing those limits first, then approach a lender whose policy suits their income type. Timing and results depend on the lender and your circumstances.

What serviceability mistakes are worth avoiding?

• Applying with several lenders before knowing which policy suits you.
• Underestimating living costs on the application, which bank statements will contradict.
• Ignoring small debts and buy now pay later accounts.
• Taking on a car loan or card shortly before applying.

The loan-ready checklist puts these into a step-by-step list.

What does serviceability look like in a simple example?

Here is an illustrative example with no real figures. Imagine a household with two incomes, one credit card with a large limit and a car loan. The lender adds up the two incomes, subtracts the household’s assessed living costs, the car loan repayment and an assumed repayment on the card limit, then tests the new loan at the buffered rate. If the remaining surplus is positive, the loan passes. If not, the lender may offer a smaller amount.

Now change one thing: the household closes the card. The assumed repayment disappears, the surplus rises and the borrowing power lifts. Nothing about their income changed, which is why careful preparation can matter as much as earning more.

Why might a loan work for one borrower and not another?

Because the inputs are personal. Two applicants on the same salary can end up with different results if one has dependants, a higher living cost, a car loan or a card limit. Lenders also assess rental income, overtime and company profit differently. Self-employed income can change depending on whether depreciation and other non-cash items are added back.

The same logic applies to business borrowers. A business loan lender may test whether the business can service the new repayments from its profit, not just the owners’ personal income. The pages on working capital loans and business loan refinance look at that from the business side.

When is a serviceability problem a structure problem?

Sometimes the loan fails not because the borrower cannot afford any loan, but because the structure asks too much. A shorter term, a higher repayment or a large lump-sum requirement can all tip the test. Changing the structure might help, for example:

• A longer term lowers the monthly repayment, though it usually increases the total cost over time.
• Interest-only for a period lowers repayments in the short run, though the principal remains.
• A smaller loan, with the balance funded another way.
• A different lender whose test suits the way you earn.

A broker can model those options with you. Where the problem is the bank test itself, rather than the real affordability, a specialist or private route may fit better.

Sounds like you want to know what you can borrow?

Sounds like you’re checking whether a loan will fit your budget before you commit. We’re the lending experts in matching borrowers to the lender whose serviceability rules fit, so click the button and see if you qualify.