Understanding the Basics of Borrowing Capacity

Your borrowing capacity is the maximum amount a lender will approve based on your income, expenses, and existing debts.

If you work at Sir Charles Gairdner Hospital or the nearby Queen Elizabeth II Medical Centre, understanding how your employment type affects this calculation can make the difference between a confident purchase in Nedlands or a property search that keeps shifting further out. Lenders treat different types of medical income differently, and knowing where you sit changes how you approach a home loan application.

How Lenders Calculate What You Can Borrow

Lenders use a serviceability formula that multiplies your net monthly income by a buffer rate, then subtracts your monthly commitments. The buffer rate sits above the actual interest rate to account for potential rate rises, usually around 3% above the current variable rate. Most banks add this buffer to your loan's interest rate, then calculate whether you could still afford the repayments if rates climbed.

Your gross income gets reduced by tax and an estimate of your living expenses based on the Household Expenditure Measure, which uses your household size and income level to determine a minimum spend on essentials. Some lenders allow you to declare lower living costs if you can justify them, but many use a fixed benchmark that rises as your income increases.

Existing debts reduce your capacity directly. A car loan with $600 monthly repayments might cut your borrowing limit by around $100,000, depending on the lender's assessment rate. Credit card limits matter more than balances because lenders assess the full limit as if you've drawn it down completely, typically calculating a minimum monthly repayment of 3% of the limit.

What Counts as Income for a Medical Professional

Base salary from a hospital contract is the most straightforward income type for lenders to assess. Permanent employees with pay slips showing consistent PAYG income get full credit for that amount, though registrars on rotating contracts sometimes need to provide additional letters confirming ongoing employment.

Overtime and allowances require a track record. Most lenders want to see at least three to six months of consistent additional income before they'll include it in your capacity calculation, and even then they might only count a percentage rather than the full amount. Shift penalties and on-call payments that appear regularly on your pay slips can be factored in, but one-off payments or irregular locum work outside your main role needs a longer pattern before it strengthens your application.

Consider a junior doctor earning $95,000 in base salary plus roughly $18,000 in overtime and penalties across a year. Some lenders will include the full overtime amount if it's clearly itemised on each pay slip over six months. Others will apply a 80% weighting or ignore it entirely if it varies too much month to month. That difference might shift your borrowing capacity by $80,000 or more, which in Nedlands could determine whether a one-bedroom apartment or a two-bedroom unit fits within reach.

How Existing Debts and Commitments Affect Your Limit

HECS-HELP debt reduces your capacity through the repayment threshold, which kicks in once your income crosses a certain point. Lenders apply a percentage based on your income bracket, treating it as a recurring monthly commitment even though the repayment comes out through your tax.

Investment properties get assessed on their rental income and loan repayments, but lenders only count a portion of the rent, usually around 80%, to account for vacancy and maintenance costs. If you own an investment property in another suburb with $500 weekly rent and a $2,200 monthly loan repayment, the lender calculates your net position as roughly $1,733 in rent minus $2,200 in repayments, leaving a shortfall that reduces what you can borrow for an owner occupied home loan in Nedlands.

Credit cards matter even when paid off each month. A $15,000 limit might reduce your borrowing power by $75,000 because the lender treats it as potential debt. Closing unused cards or reducing limits before you apply improves your position without changing your actual finances.

The Role of Deposit Size and Lenders Mortgage Insurance

Your deposit size changes your loan to value ratio, which affects whether you'll pay Lenders Mortgage Insurance and sometimes influences the interest rate you're offered. Borrowing above 80% of the property's value triggers LMI, which protects the lender if you default but gets added to your loan or paid upfront.

Some lenders offer LMI waivers for medical professionals, particularly doctors, which can mean borrowing up to 90% or even 95% of the property value without the usual insurance cost. That changes the math if you're planning to buy close to the University of Western Australia or along Stirling Highway, where properties in the $600,000 to $900,000 range are common for units and townhouses.

A larger deposit doesn't directly increase your borrowing capacity in the serviceability calculation, but it reduces the loan amount you need, which widens your property options. If your capacity sits at $550,000 and you have a 10% deposit, you're looking at properties around $610,000. Lift that deposit to 20% and the same capacity reaches properties closer to $690,000.

Variable vs Fixed Rates and Your Capacity Assessment

Lenders assess your capacity using a higher rate than the one advertised, regardless of whether you choose a variable rate or fixed rate product. The buffer rate applies to both, so the product you select doesn't change the amount you're approved to borrow, though it does affect your actual repayments once the loan settles.

A split loan approach, where part of your loan sits on a fixed rate and part on a variable rate, gives you access to features like an offset account on the variable portion while locking in certainty on the fixed portion. This doesn't increase your borrowing limit, but it does give you more flexibility to manage repayments and reduce interest over time if you direct extra income into the offset.

Some lenders offer rate discounts based on your loan size or your profession, which can lower your ongoing repayments and make it easier to service the loan comfortably, even though the approval itself was calculated at the higher buffer rate. Medical professionals sometimes qualify for additional discounts or fee waivers that aren't available to other borrowers, which improves the overall cost of the loan after approval.

Why Pre-Approval Matters Before You Start Looking

Getting home loan pre-approval gives you a confirmed borrowing limit before you attend auctions or make offers. Lenders assess your income, debts, and expenses, then issue conditional approval based on a property type and value range. It's not a guarantee, but it means you know what you can afford and where to focus your search around Nedlands, whether that's near Broadway or closer to the river.

Pre-approval usually lasts three to six months, depending on the lender. Your circumstances need to stay stable during that period, so taking on new debt or changing jobs can affect whether the approval still stands when you find a property.

In our experience, buyers who start their search without a clear sense of their capacity often waste time looking at properties outside their range or miss opportunities because they're unsure whether they can act quickly. A pre-approval from a mortgage broker who understands medical income structures and LMI waivers specific to your profession means you're comparing properties that genuinely fit your situation, not guessing.

If you're weighing up your options or trying to work out whether your current income and commitments will get you where you need to be, call one of our team or book an appointment at a time that works for you. We work with lenders who understand how medical professionals get paid and how to structure a loan that reflects what you're actually earning, not just what shows up on a single pay slip.

Frequently Asked Questions