Your borrowing capacity isn't a fixed number. It shifts with interest rates, and even a small change can make a noticeable difference to how much lenders will approve.
When lenders assess your home loan application, they calculate your borrowing capacity by working out how much you can comfortably repay. They use your income, existing debts, living expenses, and the interest rate to determine this figure. The higher the interest rate they factor into that calculation, the less you can borrow.
This matters right now for anyone planning to buy or refinance. Rate movements don't just affect your repayments once you have a loan, they also affect whether you qualify for that loan in the first place.
How Lenders Calculate What You Can Borrow
Lenders start with your gross income and subtract your existing commitments, living expenses, and a buffer on top of the current interest rate. The buffer sits between 2% and 3% depending on the lender, meaning they assess your ability to repay at a rate higher than what you'll actually pay. This is called the assessment rate.
If variable rates are sitting at 6.5%, the lender might assess your application at 9%. That buffer protects both you and the lender if rates rise after you settle. The problem is that when actual rates go up, the assessment rate goes up with them, and your borrowing capacity drops.
Consider a couple earning a combined $120,000 with minimal debts and monthly expenses around $3,000. At an assessment rate of 8.5%, they might qualify for a loan amount around $550,000. If that assessment rate moves to 9.5%, their capacity could drop by $40,000 to $50,000, even though their income and expenses haven't changed.
Why a 0.5% Rate Increase Can Cost You $50,000 in Borrowing Power
Even half a percent makes a substantial difference when lenders run the numbers. A borrower who could access a $600,000 loan at one assessment rate might only qualify for $550,000 after a modest rate increase. The mathematics behind this is straightforward: higher rates mean higher repayments, and lenders cap your repayments at a percentage of your income, usually between 30% and 35% after tax.
In practical terms, a 0.5% rise in the assessment rate increases the monthly repayment by roughly $150 to $200 on a $500,000 loan. That extra $200 per month translates to around $50,000 less in approved loan amount because lenders work backwards from what you can afford to repay.
This is particularly relevant for Victorian buyers looking in suburbs where prices sit close to their maximum borrowing limit. If you were pre-approved six months ago and rates have shifted since, your capacity may have changed too. A home loan pre-approval locks in your approval but not always the assessment rate used, depending on the lender and timeframe.
Fixed Versus Variable Rates and Your Borrowing Capacity
The type of rate you choose doesn't change how much you can initially borrow, but it does affect what happens after settlement. Lenders assess your capacity using their standard assessment rate regardless of whether you plan to fix or go variable. Once approved, however, a fixed interest rate home loan gives you certainty around repayments for the fixed period, while a variable rate means your repayments will move with the market.
Some borrowers use a split loan structure, fixing part of their loan and leaving part variable. This approach doesn't increase your borrowing capacity, but it does give you flexibility to make extra repayments on the variable portion while protecting you from rate rises on the fixed portion.
For those considering an investment loan, lenders typically apply a lower income weighting to rental income, which also reduces borrowing capacity. If interest rates rise while you're holding an investment property and looking to buy an owner-occupied property, your capacity will be assessed with both the existing investment loan and the higher assessment rate in mind.
How to Improve Your Borrowing Capacity When Rates Are High
You can't control interest rates, but you can adjust other parts of the equation. Reducing existing debts has the most immediate impact. Paying down credit cards, personal loans, or car loans reduces your monthly commitments and frees up borrowing capacity.
Lenders also look at your living expenses, and if your declared expenses are higher than the benchmark they use for someone in your situation, it can limit what you qualify for. Reviewing your spending and reducing discretionary costs in the months before you apply can help, particularly if you're borderline on your capacity.
Increasing your deposit also changes the equation slightly. While a larger deposit doesn't directly increase how much you can borrow, it reduces the loan amount you need and may help you avoid Lenders Mortgage Insurance, which in turn lowers your upfront costs. If you're close to an 80% loan to value ratio, reaching that threshold can make a tangible difference to your overall position.
What Happens to Your Borrowing Capacity When Rates Drop
When variable interest rates fall, your borrowing capacity increases in the same way it decreases when they rise. A 0.5% drop in the assessment rate could add $40,000 to $50,000 to your approved loan amount, giving you access to a higher price range or more flexibility in your property search.
This can also create opportunities to refinance into a larger loan if your property has increased in value and you need to access equity. If you purchased a property a few years ago and rates have since dropped, your borrowing capacity has likely improved, particularly if your income has increased as well.
It's worth revisiting your borrowing capacity with a broker if your circumstances have changed or if rate movements have been significant since you last applied. What you qualified for a year ago may not reflect what's available now, in either direction.
When to Lock in Pre-Approval and When to Wait
Pre-approval typically lasts three to six months depending on the lender. If you're concerned that rates might rise before you find a property, securing home loan pre-approval early gives you certainty around your budget. If you expect rates to fall, waiting might increase your capacity, but it also means you're entering the market without confirmed numbers.
For most buyers, securing pre-approval as soon as you're serious about purchasing makes sense. It gives you a clear budget, speeds up the process once you find a property, and shows sellers that you're in a position to proceed. If rates do shift after your pre-approval is issued, you can often have it reassessed before settlement, though this isn't guaranteed.
Anyone nearing the end of a fixed rate period should also consider how rate changes might affect their refinancing options. If your fixed rate expires and variable rates have risen significantly, your capacity to refinance into a different lender or a larger loan may have reduced since your original approval.
If you're weighing up how rate movements affect your specific situation or want to understand what you can borrow right now, call one of our team or book an appointment at a time that works for you.
Frequently Asked Questions
How much does a 0.5% interest rate increase reduce my borrowing capacity?
A 0.5% rise in the assessment rate typically reduces your borrowing capacity by around $40,000 to $50,000 on a loan in the $500,000 to $600,000 range. The exact impact depends on your income, existing debts, and the lender's assessment buffer.
Do lenders use the current interest rate to assess my borrowing capacity?
Lenders use an assessment rate that includes a buffer of 2% to 3% above the actual interest rate. This means if variable rates are 6.5%, you might be assessed at 9% to ensure you can still afford repayments if rates rise.
Can I increase my borrowing capacity if interest rates are high?
Yes, you can improve your capacity by paying down existing debts, reducing living expenses, or increasing your deposit. These changes free up your repayment capacity and can offset the impact of higher rates.
Does choosing a fixed rate increase how much I can borrow?
No, lenders assess your borrowing capacity using their standard assessment rate regardless of whether you choose a fixed or variable rate. The rate type you select affects your repayments after settlement, not your initial approval amount.
What happens to my borrowing capacity if rates drop after I get pre-approval?
If rates drop after pre-approval, your borrowing capacity may increase. You can ask your lender or broker to reassess your application before settlement to take advantage of the improved capacity.
