Good Debt vs Bad Debt: When to Borrow

What Makes Debt Good or Bad

Good debt generates income or builds wealth over time, while bad debt funds consumption without creating future value. The distinction comes down to whether the borrowed money produces an ongoing return that exceeds the cost of borrowing it.

Consider a homeowner in Applecross who owes $400,000 on their mortgage. That same property now holds $850,000 in equity. They could access $200,000 of that equity to purchase an investment property in a growth suburb, where rental income covers most of the loan repayments and the property appreciates over time. The new loan creates tax-deductible interest, generates rental income, and builds a second asset. That's good debt.

The same homeowner could instead use that $200,000 equity to buy two new cars, renovate the kitchen, and take an overseas holiday. Those purchases provide immediate enjoyment but produce no income, offer no tax benefit, and depreciate from the moment the money is spent. That's bad debt.

The loan amount is identical in both scenarios. The interest rate might even be the same. What changes is what the borrowed money does after you receive it. Good debt works for you. Bad debt works against you.

Perth property owners often carry both types simultaneously. A home loan that funds your family residence sits in the middle - it's not generating income, but it's building equity in an appreciating asset rather than funding consumption. An investment loan secured against that equity can shift the equation entirely when structured correctly.

How Tax Treatment Changes the Calculation

Investment loan interest is tax-deductible when the borrowed funds are used to generate assessable income. Home loan interest is not.

If you're paying $24,000 per year in interest on a non-deductible home loan and you earn a marginal tax rate of 37%, that interest costs you the full $24,000. If you're paying the same $24,000 in interest on an investment loan, the after-tax cost drops to around $15,000 because the ATO allows you to deduct the interest from your taxable income.

This difference compounds over decades. A $400,000 home loan at current variable rates costs hundreds of thousands in non-deductible interest over its life. A $400,000 investment loan at the same rate costs significantly less after tax, while the underlying investment generates rental income and potential capital growth.

The key is maintaining clear separation between the two. The ATO requires that borrowed funds used for investment purposes remain quarantined from personal use. Mixing purposes, even unintentionally, can void the deduction entirely. A split loan strategy keeps investment borrowings separate from personal borrowings, protecting the tax treatment while giving you flexibility over repayment priorities.

Debt Recycling Converts One Type Into the Other

Debt recycling systematically replaces non-deductible home loan debt with tax-deductible investment debt. You're not borrowing more money overall - you're changing what the debt is attached to.

As an example, a couple in Mount Pleasant owe $350,000 on their home loan. They have $1,800 per month in surplus cashflow after all expenses. Instead of directing that surplus entirely toward the mortgage, they split it. Half goes to the home loan as usual. The other half goes into an offset account linked to a new investment loan, which they use to build a portfolio of income-producing assets like shares or managed funds.

Each month, as the home loan balance drops by $900, they redraw that same amount and add it to the investment loan offset. The total debt stays roughly the same, but the proportion that's tax-deductible grows steadily. Over time, the entire mortgage converts into investment debt. The investments generate dividends, franking credits, and potential growth. The interest becomes fully deductible. The outcome is a paid-off home and a growing investment portfolio funded by what was previously dead mortgage debt.

This approach works particularly well for homeowners who have already built equity and want to accelerate wealth accumulation without reducing their cash reserves. The structure requires discipline and correct record-keeping, but the tax and wealth-building benefits compound over time. For detailed guidance on implementing this approach, refer to implementing your strategy.

When Bad Debt Makes Sense

Not all consumption debt is irrational. Borrowing for a car when you need reliable transport to earn income can be a practical decision, even though the loan itself doesn't produce a return. Renovating a kitchen might improve your quality of life or increase your property's resale value, even if the loan interest isn't deductible.

The issue isn't whether you should ever borrow for personal use. It's whether you're conscious of the trade-off and whether the debt is proportionate to your income and goals.

Someone earning $180,000 per year who borrows $15,000 for a car they'll use for a decade is making a different calculation than someone earning $60,000 who borrows $50,000 for a vehicle that loses half its value in three years. The first can absorb the repayments without limiting their capacity to build wealth elsewhere. The second is locking themselves into years of repayments that prevent them from saving a deposit, accessing investment finance, or building equity.

If you're going to carry consumption debt, keep it short-term, keep the balance small relative to your income, and avoid extending the term to reduce repayments. A five-year car loan at a fixed rate is manageable. A seven-year loan that gets refinanced into a 30-year mortgage when you consolidate debts is a liability that will cost you decades of compounding investment returns.

Equity Doesn't Become Good Debt Automatically

Accessing equity to invest only works if the investment produces a return. Borrowing $300,000 against your home to buy an investment property in a declining market with poor rental yield doesn't convert bad debt into good debt - it just adds risk.

The quality of the underlying investment matters as much as the loan structure. In Perth, suburbs with strong infrastructure, proximity to employment hubs, and consistent rental demand tend to deliver more reliable returns than speculative purchases in unproven locations. An investment property in Subiaco or Fremantle, close to universities, hospitals, and the CBD, will typically hold tenants and value more consistently than a cheaper property in a remote suburb with limited amenity.

Before committing equity to any investment, calculate whether the expected return exceeds the borrowing cost after tax. If rental income and projected growth don't outpace the interest expense, even with the deduction factored in, the debt isn't working for you - it's just leveraged speculation. Investment loans should be backed by clear income and growth projections, not assumptions that property always goes up.

ATO Compliance Protects the Deduction

The ATO watches for debt recycling structures that don't follow the rules. If you redraw funds from your home loan and invest them, the interest on the redrawn portion becomes deductible only if you can prove the funds were used solely for investment purposes.

Keeping separate loan accounts for personal and investment purposes is non-negotiable. Using a dedicated offset account linked to the investment loan ensures you never co-mingle funds. Documenting every transaction, keeping statements, and maintaining a clear audit trail protects you if the ATO ever reviews your return.

You can't claim a deduction for interest on funds used to pay personal expenses, even if those funds were originally drawn for investment purposes. If you borrow $100,000 to buy shares and later withdraw $20,000 from the investment account to renovate your bathroom, the interest on that $20,000 is no longer deductible. The moment investment funds are redirected to personal use, the tax treatment changes.

A mortgage broker experienced in debt recycling will structure the loan to maintain compliance from the outset, so you're not discovering issues years later when the ATO queries your deductions.

How Cashflow Shapes Your Capacity

Debt recycling only works if you have surplus cashflow to service both the home loan and the investment loan simultaneously. If your income barely covers your current mortgage, adding investment debt will strain your budget, regardless of the tax benefit.

Before committing to this approach, calculate your cashflow after all expenses, including the new investment loan repayments. If rental income from an investment property or dividends from shares cover part of the interest, factor that in. But don't assume investment income will always arrive on time or remain consistent. Vacancy periods, dividend cuts, and market downturns happen. You need enough buffer in your cashflow to cover the full loan repayment without relying on investment income.

For homeowners with variable incomes or upcoming life changes - such as parental leave, business expansion, or planned study - locking into a high level of investment debt can create pressure. In those cases, starting with a smaller allocation and scaling up as your cashflow stabilises makes more sense than committing maximum equity upfront.

If your current debt level already stretches your serviceability, focus on paying down the home loan or increasing your income before adding investment borrowings. Debt recycling accelerates wealth building, but only when your financial foundation can support the structure. For tailored advice, consider accessing finance through a broker who understands your capacity.

Call one of our team or book an appointment at a time that works for you. We'll assess your current debt position, calculate your capacity, and structure a loan that aligns investment growth with your cashflow and goals.

Frequently Asked Questions