Australian lenders assess a home loan at an interest rate at least three percentage points above the rate on the product, because APRA expects it. They also compare declared living expenses against a household expenditure benchmark, which ASIC says gives no positive confirmation of what a borrower actually spends. Both tests shrink the amount a lender will advance below what a simple repayment calculation suggests.
A borrowing estimate and a lender's answer are produced by different arithmetic, and the gap between them is not an error in either. Two supervisory decisions sit in between, and both of them shrink the number.
Key Takeaways
- APRA expects lenders to assess new borrowers at a rate at least three percentage points above the rate on the loan product.
- That expectation rose from two and a half points on 6 October 2021 and still stands as at September 2026.
- Living expenses are checked against a benchmark, most commonly the Household Expenditure Measure.
- ASIC's position is that a benchmark gives "no positive confirmation" of what a borrower's expenses actually are.
- Declaring expenses below the benchmark triggers more questions rather than a larger loan.
The loan is tested at a rate nobody pays
Since 6 October 2021 the Australian Prudential Regulation Authority has expected authorised lenders to "assess new borrowers' ability to meet their loan repayments at an interest rate that is at least 3.0 percentage points above the loan product rate". The expectation replaced a buffer of two and a half points that had been common across the industry.
APRA's reasoning is prudential rather than about any individual borrower. The buffer is a contingency against rises in interest rates over the life of a loan, and against unforeseen changes in a borrower's income or expenses. The regulator's stated objective was to ensure lending is conducted on a prudent basis and that borrowers can service their debts under a range of scenarios.
Two consequences follow, and they are the whole reason a lender's number is smaller.
The buffer is never charged. It is a test the application has to survive on paper, and no borrower ever pays the buffered rate.
The buffer moves with the product rate rather than sitting at a fixed level. Because it is expressed as a margin above whatever rate is achieved, negotiating the rate down does not escape it. Whatever rate a borrower wins is then buffered upward by the same three points before the test is run.
Expenses are declared, then checked against a benchmark
Australian lenders operate under the responsible lending obligations in Chapter 3 of the National Consumer Credit Protection Act. ASIC's guidance requires making reasonable inquiries about a consumer's financial situation and taking reasonable steps to verify it.
In practice most lenders compare a borrower's declared living expenses against a benchmark. The most widely used is the Household Expenditure Measure, which scales with household composition, location and income.
What that benchmark can do is narrower than it looks. ASIC's statement is exact: a benchmark figure "does not provide any positive confirmation of what a particular consumer's income and expenses actually are, but can be a useful tool to help determine whether information provided by the consumer is plausible".
So the benchmark is a plausibility test, not a measurement. It is checking the shape of the declaration rather than establishing the truth of it.
Why a low expense declaration backfires
This is the part borrowers most often get wrong, and the guidance is explicit about the mechanism.
Because the benchmark methodology rests on the majority of households spending more than the benchmark figure, a declaration below it is statistically more likely to be an underestimate. ASIC's position is that where a consumer provides estimates lower than the benchmark, "there is a higher likelihood that they have underestimated", and that this "should therefore trigger additional information-gathering steps".
The guidance is equally clear about the other direction. Where the additional information confirms the lower figure, ASIC does not consider it necessary to raise the verified amount back up to a floor. A genuinely frugal household is not penalised; it is asked to evidence the claim.
Understating expenses therefore buys scrutiny rather than capacity, and an application that has to be re-documented is slower than one that was accurate first time.
The three assumptions a calculator has to make
Beyond the buffer and the benchmark, an estimate stands in for several judgements that a lender makes case by case.
Income is taken at face value. Lenders discount income that is variable or less secure. Overtime, bonuses, commissions and rental income are commonly counted at less than their full amount, and the discount differs between lenders. None of those policies are published.
Credit limits stand in for balances. Revolving credit is generally assessed against the approved limit rather than the balance outstanding, on the reasoning that the limit is what a borrower could draw tomorrow. A reduced limit changes the input the assessment uses; repaying a balance while leaving the limit in place does not.
Tax is modelled rather than read. Gross income is converted to net using general resident rates. Offsets, salary packaging, investment losses and a second income taxed at a different marginal rate all sit outside that conversion.
What the assessment cannot see at all
Two things sit entirely outside a serviceability calculation, and both can decide an application on their own.
The deposit sets the loan-to-value ratio, which determines whether lenders mortgage insurance is required and can change the rate on offer. The property itself matters too, because some types and locations are lent against more cautiously than others.
Neither is a serviceability question. A household can pass the repayment test comfortably and still be declined on security, which is why an estimate is a starting point for a conversation rather than a decision.
Where to look next
The current published averages for lending and deposit rates sit on the rate pages, and the cash rate is the policy rate they respond to. An offset account changes the interest charged on a loan without changing how the loan is assessed, which is a distinction worth holding onto: the assessment is about capacity, and an offset is about cost.
Sources
- Australian Prudential Regulation Authority, serviceability expectations - the three percentage point buffer, from 6 October 2021
- ASIC Regulatory Guide 209, Credit licensing: Responsible lending conduct - reasonable inquiries and verification
- ASIC Report 643, Response to submissions on CP 309 - what an expenditure benchmark does and does not confirm
Not financial advice, not credit assistance, and not a recommendation of any product or institution. Reviewed by the Tradergy editorial team, September 2026.
Common questions
What is the serviceability buffer?
It is the margin a lender adds to the product rate before testing whether a borrower can afford the repayments. APRA expects authorised lenders to assess new borrowers at a rate at least three percentage points above the rate on the loan. The borrower never pays the buffered rate; it exists so the loan still works if rates rise.
Does declaring lower living expenses increase how much I can borrow?
No, and it tends to have the opposite effect. Lenders compare declared expenses against a benchmark, and ASIC's guidance says an estimate below the benchmark means there is a higher likelihood the borrower has underestimated, which should trigger additional information gathering rather than a larger loan.
Why does an unused credit card reduce my borrowing power?
Revolving credit is generally assessed by reference to the approved limit rather than the balance outstanding, because the limit is what the borrower could draw at any time. A card with a large limit and nothing owing still consumes assessed capacity.
Is a borrowing estimate the same as pre-approval?
No. An estimate applies general assumptions to typed figures. A lender applies its own credit policy to verified documents, and considers the deposit, the property and the credit file, none of which an estimate can see.
Why do two lenders give different answers on the same figures?
Because the regulatory expectation is a floor rather than a formula. Each lender sets its own expense floors, its own discounting of variable income, its own treatment of dependants, and its own buffer above the minimum. None of that is published.