Home Loan Serviceability • Borrowing Power • APRA

Why Banks Assess Your Home Loan at a Rate You're Not Actually Paying

Your home loan rate might be 6%. Yet the bank could assess your borrowing power as though the rate were around 9%.

That does not mean the bank thinks you are about to start paying 9%. It is a stress test — and it can make a very large difference to how much you are allowed to borrow.

The important bit is that not every lender uses exactly the same serviceability rules. Banks, non-banks and specialised refinance products can sometimes assess the same borrower very differently.

THE APRA bank buffer 3%

Example actual rate 6.0%

Example bank assessment 9.0%

THE High-DTI threshold 6×

APRA sets the minimum for regulated banks — not every lender's calculator

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The 3% buffer

Why does a bank test a 6% home loan at around 9%?

APRA requires regulated banks, credit unions and building societies to apply a minimum serviceability buffer of 3 percentage points when assessing new residential mortgage lending.

So, if the actual home loan rate is 6.00%, the lender will generally need to test the borrower at a rate of at least around 9.00%, subject to the lender's own assessment floor and policy.

The lender is not saying your rate will become 9%. It is asking whether your household could still support the loan if conditions became more difficult.

APRA confirmed in May 2026 that the 3% buffer would remain in place.

Why it exists

The buffer is designed to leave room for things going wrong

A 30-year mortgage has to survive more than today's household budget.

Over the life of a loan, interest rates can change, household expenses can rise and income can fall.

The serviceability buffer is designed to create some breathing room for those risks.

Interest rates Mortgage rates can rise after the loan is approved.

Household expenses Food, utilities, insurance, childcare and other costs can increase.

Income changes Reduced hours, parental leave or employment changes can alter household income.

Unexpected costs A household budget rarely remains identical for 20 or 30 years.

From a borrower's perspective, the frustrating part is obvious: the higher assessment rate can materially reduce borrowing capacity even when the real repayment feels affordable.

Borrowing power

The repayment you can afford is not necessarily the repayment the lender tests

This is why borrowers sometimes look at a repayment calculator and wonder why the bank will not lend them the amount they expected.

You might calculate that a particular loan costs $4,000 per month at the current rate.

The lender's serviceability model is effectively asking a different question:

Could this household still support the loan if we assess the debt using our stressed repayment assumptions?

That higher theoretical repayment is one of the reasons the bank's maximum borrowing figure can be lower than the amount a borrower feels comfortable paying today.

The part people miss

Not every lender uses the same serviceability buffer

This is where the Australian lending market gets more interesting.

APRA's 3% minimum applies to APRA-regulated authorised deposit-taking institutions — broadly, banks, credit unions and building societies.

Non-bank lenders are not automatically subject to that same ADI serviceability-buffer requirement.

Regulated bank example A 6.00% loan may be assessed at around 9.00% under the standard 3% minimum buffer.

Some non-bank examples Certain non-bank lenders use a 2% buffer, subject to their own assessment floor and lending policy.

Specialised refinance examples Some eligible refinance pathways have used a 1% buffer under tightly defined lender policy.

Policy still matters Lower-buffer lending is not universal and does not remove responsible-lending or credit assessment requirements.

APRA sets the 3% minimum for regulated banks. It does not make every lender's servicing calculator identical.

The 2% buffer

Some non-bank lenders assess differently

Resimac is one example of a non-bank lender with published policy that uses the higher of its applicable floor rate or the actual interest rate plus 2.00%.

Using the same simple example:

3% bank buffer 6.00% actual rate + 3.00% = approximately 9.00% assessment.

2% non-bank example 6.00% actual rate + 2.00% = approximately 8.00% assessment, subject to the lender's floor and policy.

A one percentage-point difference in the assessment rate can materially change borrowing capacity.

But it would be wrong to say all non-bank lenders use 2%.

Some non-banks use 2%. Others use different buffers, floor rates and servicing models.

The 1% buffer

Some refinance pathways can assess eligible borrowers more gently

There are also lender-specific refinance policies where eligible borrowers can be assessed using a 1% buffer.

These policies are generally designed for borrowers who are already demonstrating that they can repay an existing mortgage and are refinancing without materially increasing their debt.

Examples have included pathways requiring conditions such as:

strong mortgage repayment conduct;
no significant adverse change in income;
no significant adverse change in expenses;
acceptable LVR;
dollar-for-dollar or limited-increase refinancing;
appropriate loan term; and
acceptable credit history.

A 1% refinance buffer is lender policy for specific eligible scenarios. It is not an APRA rule replacing the standard 3% bank buffer.

That distinction matters enormously.

Mortgage prison

This is why one refinance can fail while another may work

Consider a borrower with an existing mortgage rate of 6.20%.

Standard bank assessment A 3% buffer could mean an assessment rate around 9.20%.

2% lender example A different lender may assess around 8.20%, subject to its policy.

Eligible 1% refinance pathway A specialised refinance assessment could be around 7.20% if the borrower meets all relevant criteria.

Same borrower Income and debt may be unchanged while the servicing outcome changes because the assessment methodology is different.

That does not mean every borrower who fails a standard bank assessment can simply move to a lower-buffer lender.

Income, expenses, LVR, credit conduct, property type and the rest of the lender's policy still matter.

A borrower who fails one servicing calculator may not necessarily fail every servicing calculator.

Bank exceptions

Even the 3% bank rule has controlled exceptions

APRA has also acknowledged that regulated banks can approve limited exceptions to standard servicing policy where those exceptions are prudently managed.

In refinance situations, lenders may consider other evidence of repayment capacity, including a borrower's past repayment behaviour.

That does not mean a borrower can simply ask the bank to ignore the buffer.

An exception is controlled lender policy — not a loophole.

The lender still needs appropriate controls, credit assessment and a defensible reason for approving the loan.

More than the mortgage

The lender is assessing your whole household position

The serviceability buffer gets most of the attention, but it is only one part of borrowing capacity.

Lenders also assess the household's income, living costs and existing commitments.

Income Salary, overtime, bonuses, allowances, commissions and self-employed income may be treated differently.

Household costs Living expenses, childcare, school fees, insurance and dependants can materially affect servicing.

Existing debts Mortgages, car loans, personal loans, HELP debt and other liabilities can reduce borrowing power.

Credit limits Unused credit-card limits can still be treated as potential commitments.

Credit cards

A $500 balance on a $20,000 card can still matter

Borrowers often focus on the amount owing on a credit card.

Lenders can instead assess the available credit limit because the borrower has access to that facility.

So a card with a $20,000 limit can affect borrowing capacity even if only $500 is currently outstanding.

Unused credit can still be treated as potential debt.

That does not mean every borrower should cancel every card. It means genuinely unnecessary limits are worth reviewing before a lending application.

Rental income

Your $700-a-week rent may not count as $700-a-week servicing income

Investment-property income is another area where lender policy can differ.

A lender may apply a percentage or other adjustment to rental income rather than counting every dollar.

That allows for things such as vacancies, management costs and other property expenses.

This is one reason two lenders can assess the same investment borrower and produce very different borrowing figures.

DTI versus serviceability

These are two different lending tests

Debt-to-income ratio, or DTI, is often confused with serviceability.

Serviceability Can the household support the repayments under the lender's stressed assessment assumptions?

DTI How large is the borrower's total debt compared with annual income?

From February 2026, APRA requires regulated banks to keep lending at DTI of 6x or more within portfolio limits — 20% of new owner-occupier lending and 20% of new investor lending, measured separately.

A DTI above 6x is not banned. It falls into a high-DTI lending category subject to lender-level limits.

A borrower can therefore pass a serviceability calculation and still face DTI constraints, or vice versa.

Rate movements

Lower home loan rates can improve borrowing power

Because the serviceability buffer is added to the actual interest rate, a lower product rate can also reduce the assessment rate.

At 6.50% A standard 3% buffer produces an assessment rate around 9.50%.

At 5.80% The same 3% buffer produces an assessment rate around 8.80%.

The borrower's income may not have changed at all, yet borrowing capacity can improve because the stressed repayment falls.

Your real budget

The maximum a lender will approve is not automatically what you should borrow

This is probably the most important part of the whole serviceability conversation.

A bank, credit union or non-bank lender may calculate that you can borrow $850,000.

That number is the maximum produced by that lender's credit rules.

It does not know how much breathing room you personally want for holidays, family plans, savings, future children, career changes or simply sleeping comfortably at night.

Borrowing capacity is a ceiling produced by a lender's rules. Your own budget should determine how close you actually want to go to it.

Not sure why your borrowing power is lower than expected?

We can look at the income, expenses, debts, credit limits, LVR and lender servicing rules behind the result — including whether another lender genuinely assesses your position differently.

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The bottom line

There is no single Australian home loan calculator

APRA's 3% serviceability buffer is a major part of home lending, but it is not the entire market.

Regulated banks generally operate under the 3% minimum. Some non-bank lenders use different approaches, including 2% buffers. Some specialised refinance policies can use a 1% buffer for tightly defined eligible borrowers.

At the same time, lenders can differ in how they treat income, expenses, rental income, credit cards and other debts.

Different lenders can look at the same borrower and legitimately reach different borrowing-capacity results.

The objective should not be to find whichever calculator produces the biggest number.

It should be to understand why the numbers differ, which lender policy genuinely fits the situation and whether the resulting loan remains comfortable.

Sources and further reading: APRA — Macroprudential policy settings, May 2026; APRA — Housing lending standards and policy exceptions; Resimac — Product and Policy Guide; MFAA — Refinance serviceability.

Borrowing Power

Understand the number before you chase the maximum.

Loan Location can compare how suitable lenders assess your income, debts, expenses, LVR and serviceability — including bank and non-bank options where appropriate.

The aim is not to manufacture the biggest possible loan. It is to understand the real options and find a structure that makes sense for you.

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Important information: This article contains general information only and does not take into account your objectives, financial situation or needs. Serviceability buffers, assessment floors, lender policies, regulatory settings and product eligibility can change. Lower-buffer assessments are not available to every borrower or for every loan purpose. All lending remains subject to lender assessment, responsible-lending requirements, terms, conditions, fees and eligibility criteria. A higher borrowing-capacity result does not mean a larger loan is appropriate for your circumstances.