Buying a commercial office building is a different game to residential property, and the wrong loan structure can lock you into repayments that don't suit how the building actually performs.
Most buyers get caught between two decisions: whether to secure the loan against the office building itself or use other assets as collateral, and whether to fix the interest rate or leave it variable. Both choices have consequences that play out over years, not months, and both depend on what you're planning to do with the building once you own it.
Using Residential Property as Security Instead of the Office Building
If you're buying a commercial office building, lenders will typically prefer to secure the loan against that building. The alternative is using residential property or other business assets as collateral, which some buyers consider when the office building doesn't yet have tenants or when the loan amount is small relative to the property value.
Consider a buyer purchasing a commercial office in Mount Eliza near the Canadian Bay Road precinct. The building is vacant and needs a refurbishment before it can attract tenants. The buyer owns their home outright and decides to secure the loan against the residential property instead of the office building. This lets them access better interest rates and avoid the valuation and leasing conditions the lender would impose on an empty commercial building. Once tenants are in place and the building is performing, they refinance and move the security onto the office building itself, freeing up the home.
The risk is that if the business struggles or tenants leave, the residential property is on the line. This structure works when you have a clear timeline to move the security and a strong cash flow to service the debt in the meantime.
Choosing a Loan Structure That Doesn't Match Your Tenancy
Commercial lending comes with different loan structures, and the one that suits an owner-occupied office building is not the same as one suited to a leased investment property. If you're occupying the building yourself, you need flexible repayment options that can adjust as your business cash flow changes. If you're leasing the building to tenants, you want a structure that aligns with lease terms and rental income.
A business term loan with principal and interest repayments works when rental income is steady and predictable. Interest-only periods suit buyers who need time to fill the building or who want to redirect cash flow into refurbishments or business expansion. Some lenders also offer progressive drawdown, which is useful if you're buying a building that needs fitout or staged improvements.
In our experience, buyers who choose a rigid loan structure without considering how the building will be used end up refinancing within two years. That means paying discharge fees, application fees, and potentially break costs if they're on a fixed rate.
Ignoring the Debt Service Coverage Ratio and What It Means for Borrowing Capacity
Lenders assess commercial loans differently to home loans. Instead of looking at your personal income, they focus on whether the building can service the debt. The debt service coverage ratio measures the building's net operating income against the loan repayments. Most lenders want to see a ratio of at least 1.2, meaning the building earns 20% more than the loan costs each year.
If you're buying a building with existing tenants, the lender will use the current lease income to calculate this ratio. If the building is vacant or you're planning to occupy it yourself, they'll assess your business financial statements and cashflow forecast. Without strong business cash flow or a clear leasing strategy, the loan amount you can access will be lower than you expect, even if the building itself is valuable.
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Fixed Interest Rates Without Understanding Break Costs
A fixed interest rate on a commercial loan gives you certainty, but it also limits what you can do if your circumstances change. If you decide to sell the building, refinance, or pay down the loan early, you'll likely face break costs. These can run into tens of thousands of dollars, depending on how much interest rates have moved since you locked in the rate.
Variable interest rates cost more when rates are rising, but they give you the flexibility to make extra repayments, use redraw, or exit the loan without penalty. Some lenders offer a split structure, where part of the loan is fixed and part is variable. This works well if you want some certainty but also want the option to pay down debt as rental income or business cash flow improves.
The mistake is fixing the rate without thinking through what happens if you need to move before the fixed term ends. If you're planning to develop the site, bring in a business partner, or sell within a few years, a variable rate or shorter fixed term is usually the better choice.
Not Factoring in Ongoing Costs Beyond the Loan Repayments
Buying a commercial office building means taking on costs that don't exist with residential property. You'll pay for building insurance, strata fees if applicable, land tax, council rates, and ongoing maintenance. If the building is leased, you'll also need to cover outgoings that aren't recovered from tenants, such as vacant periods, property management fees, and any capital works required under the lease agreement.
These costs affect your cash flow and your ability to service the loan. Lenders will factor them into the debt service coverage ratio, but buyers often underestimate how much they add up. In Mount Eliza, where older commercial buildings near the village centre may need updates to meet current building standards, maintenance costs can be higher than expected.
If you're using the building for your own business, you also need to account for fitout costs, which are usually separate from the loan and paid upfront. Some lenders offer asset finance or equipment financing alongside the commercial loan, but this increases your total debt and reduces the amount you can borrow for the building itself.
Assuming You Can Refinance Easily If Your Business Situation Changes
Commercial loans are harder to refinance than home loans. If your business revenue drops, tenants leave, or the building's value falls, lenders won't offer the same terms you had at purchase. Some will reduce the loan amount, increase the interest rate, or require additional security.
This becomes a problem if you've structured the loan assuming you'll refinance in a few years to access equity or move to another lender. If the building is underperforming when that time comes, you'll be stuck with the original loan terms or forced to inject more capital to make the refinance work.
The way to avoid this is to choose flexible loan terms at the start. A longer loan term with the option to increase repayments gives you breathing room if the business or building doesn't perform as expected. A revolving line of credit or business line of credit attached to the loan can also provide working capital without needing to refinance the entire facility.
Not Getting Pre-Approval Before You Start Looking
Most buyers look at commercial office buildings before they know what they can borrow. Commercial lending takes longer than residential lending because lenders need to assess the building, review your business financial statements, and sometimes request a business plan or cashflow forecast. If you're relying on rental income from the building, they'll also want to see lease agreements and tenant details.
Without pre-approval, you risk making an offer on a building that doesn't meet the lender's criteria or that requires a larger deposit than you have available. Some lenders won't finance buildings in certain locations, buildings with specific tenant types, or buildings that need significant refurbishment. If you find out after signing a contract, you'll either need to find another lender quickly or lose your deposit.
Pre-approval for a commercial loan isn't as definitive as it is for a home loan, because the final approval depends on the building itself. But it gives you a clear picture of your borrowing capacity, the loan structure available, and what the lender will require before settlement. Working with a broker who specialises in commercial lending means you'll know which lenders suit your situation and what documentation you need to have ready.
Call one of our team or book an appointment at a time that works for you. We'll walk through your situation, the building you're looking at, and the loan structure that makes sense for your business and your cash flow.
Frequently Asked Questions
Can I use my home as security for a commercial office building loan?
Yes, some lenders allow you to secure a commercial loan against residential property, which can offer better interest rates and avoid valuation issues with vacant or underperforming commercial buildings. This works when you have a clear plan to move the security onto the office building once it has tenants or is performing well.
What is the debt service coverage ratio and why does it matter?
The debt service coverage ratio measures whether the building's income can cover the loan repayments. Lenders typically want a ratio of at least 1.2, meaning the building earns 20% more than the loan costs each year. Without strong building income or business cash flow, your borrowing capacity will be lower than expected.
Should I fix the interest rate on a commercial office building loan?
A fixed rate gives you certainty but limits flexibility if you need to sell, refinance, or pay down the loan early, as you'll likely face break costs. Variable rates cost more when rates rise but allow extra repayments and early exit without penalty. A split structure can offer both certainty and flexibility.
How long does commercial loan approval take?
Commercial lending takes longer than residential because lenders assess the building, your business financials, and sometimes request a business plan or cashflow forecast. Pre-approval helps, but final approval depends on the building itself and can take several weeks.
What ongoing costs should I budget for when buying a commercial office building?
Beyond loan repayments, you'll pay building insurance, land tax, council rates, maintenance, and property management fees if leased. If the building is vacant or needs updates, factor in fitout costs and capital works, which can reduce your cash flow and borrowing capacity.
