An interest rate change affects borrowing capacity because lenders test every loan at an assessment rate: the loan's actual rate plus a serviceability buffer. When rates move, the assessment rate moves with them, but your income, living expenses and other debts do not, so capacity usually shifts less than the headline suggests.
On episode 112 of the podcast, Dion makes the case that preparation beats prediction: investors who wait for the market to tell them when to move tend to move late. This article looks at one prediction in particular, the idea that a rate change will decide how much you can borrow.
How does a lender test whether you can afford a loan?
A lender does not test your repayments at the rate you will actually pay. It tests them at a higher rate, to make sure the loan still works if rates rise. According to APRA, the serviceability buffer lenders apply to home lending “will remain at 3 percentage points” (APRA, 28 May 2026). That means lenders assess new loans at a rate at least three percentage points above the loan's actual rate.
Some lenders also apply their own minimum assessment rate. Whichever is higher is the number your application is measured against.
What does a rate change actually change?
| Part of the assessment | Changes when rates move? | Why |
|---|---|---|
| Assessment rate on the new loan | Yes | It is built on the actual rate, plus the buffer |
| Assessed repayments on existing loans | Often, depending on lender policy | Many lenders assess other debts at a buffered rate too |
| Your income | No | Lenders assess what you can prove |
| Your living expenses | No | Assessed on your declared spending or a benchmark, whichever is higher |
| Credit card limits and other debts | No | Assessed on the limit, not the balance |
| The buffer itself | Only if APRA changes it | Set by the regulator, not by the rate cycle |
Only the first two rows move with rates. Everything else in the calculation stays where it was. That is why a rate change can feel significant in the news and modest in an assessment.
Why can two people see very different results from the same rate change?
Because the rate is only one input. An investor with a strong income, low expenses and few other debts may find a rate change moves their capacity noticeably. An investor whose capacity is limited by expenses, credit limits or the way existing loans are structured may find it barely moves at all.
The structure of existing loans matters most here. Loans that are cross-secured, split poorly or carrying limits nobody uses can hold capacity back regardless of where rates sit.
Should you wait for rates to change before buying?
Waiting is a strategy only if you know what you are waiting for. The episode puts it simply: you cannot control the market, but you can control how prepared you are. No one knows exactly when or how far rates will move, and property prices do not pause while buyers wait.
A better question is what your position looks like today, and what would change it. Sometimes the answer is a rate change. More often it is a credit limit that can be reduced, a loan that can be restructured or an expense that is being assessed higher than it needs to be.
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What can you control instead of the rate?
- Unused credit limits. Lenders assess the limit, not the balance. A card you never use still counts.
- The structure of existing loans. How loans are split and secured affects what each lender will allow next.
- Declared expenses. Accurate, current spending figures, rather than estimates.
- The order of lenders. Different lenders assess the same position differently, so the sequence of applications can matter.
- Timing of income evidence. Especially for self-employed borrowers, whose income is assessed from completed financial periods.
How often does borrowing capacity need to be checked?
Whenever something material changes: income, debts, expenses, a lender's policy or the rates themselves. An assessed position is a snapshot. Rechecking it before you start looking, and again before you make an offer, is how you stay ready to move when the right property appears.
Common questions
Does a rate cut increase borrowing capacity?
It can, but usually by less than people expect. Lenders assess loans at the actual rate plus a serviceability buffer, which APRA has kept at 3 percentage points, so a lower rate lowers the assessment rate. Income, living expenses and other debts are unchanged, so the overall effect depends on what is limiting your capacity in the first place.
What is the serviceability buffer?
The serviceability buffer is the margin lenders add to a loan’s actual interest rate when testing whether a borrower can afford it. According to APRA’s May 2026 decision, the serviceability buffer remains at 3 percentage points. Some lenders also apply their own minimum assessment rate.
Should I wait for interest rates to fall before buying an investment property?
No one can reliably predict when or how far rates will move. A more useful step is to understand your borrowing position today and what is limiting it, such as credit limits, loan structure or declared expenses, so you are ready to act when the right property appears. This is general information, not a recommendation to buy or wait.
Why didn’t my borrowing capacity change much when rates moved?
Because only part of the assessment moves with rates. Your income, living expenses, credit card limits and other debts are assessed the same way regardless of the rate, so if one of those is the main constraint, a rate change may make little difference.
The takeaway
Rates change the assessment rate. They do not change your income, your expenses or the way your loans are structured, and those often decide more.
Rather than predicting the next move, know your position now. If you want it checked properly, Book a Call.
This article is general information only. It does not take your individual circumstances into account and is not credit, tax, legal or financial product advice. All lending is subject to individual assessment and lender criteria. Speak with your own advisers before acting. No interest rate, term or approval is offered or implied.