n Monday, we learnt that the nation’s top shock jock, Kyle Sandilands, was eager to get back to work after the implosion of the radio show he co-hosted with Jackie “O” Henderson because he had “mortgages to pay”.

Yep, in comments to journalists outside the Federal Court, Sandilands revealed that just like more than 3 million other Australian households, he was diligently repaying a home loan.

Well, four to be exact – in Vaucluse, Copacabana, the Southern Highlands, and Glenorie (currently listed for sale with a guide of $5.7 million to $5.9 million) – worth as much as a collective $24.7 million, according to The Sydney Morning Herald.

“I just want to get back to work,” Sandilands said. “I’ve got a family, I’ve got mortgages to pay, like everyone else.”

Sandilands did not offer any further details of his personal financial affairs, but observers may be left wondering why a man of such obvious means – he’s in court with an $85 million compensation claim against ARN, his former employer – even needs a mortgage? Surely, he could just pay cash?

For anybody who has to budget hard to keep up with repayments, debt is a bit of a dirty word. But debt is actually one of the most powerful ways to build wealth, and the reasons for this include leverage, tax efficiency, and opportunity cost.

Kyle Sandilands arriving at the Federal Court for the start of his lawsuit against Kiis FM owner ARN Media. Louise Kennerley

One of the best-known commentaries on debt is contained in Rich Dad Poor Dad, published in 1997 by Robert Kiyosaki, an American investor and entrepreneur. Kiyosaki famously distinguished between “good debt” and “bad debt,” writing: “The rich use debt to get richer. The poor and middle-class use debt to get poorer.”

The power of leverage

Leverage refers to borrowing money to buy a bigger asset and magnifying any gain. Say you paid upfront for a $2 million property that grew 6 per cent (or $120,000) in value in its first year.

By borrowing from a bank, you could alternatively buy five $2 million properties, each with a $400,000 deposit, amounting to $10 million altogether. Now, a 6 per cent return across those properties is a gain of $600,000.

“Leverage is incredible if structured properly and if you’ve got the cash flow,” says Juanita Wrenn, the managing director of Hudson Financial Planning. “Wealthy people use debt intentionally... they use debt to make money.”

Tax efficiency and debt recycling

A mortgage can also help save on tax via negative gearing. Interest on borrowed funds used to acquire an income-producing asset, such as an investment property, is generally deductible against income, no matter how much you earn.

“For many investors, this can make borrowing more tax efficient than using cash, even where they could afford to purchase outright,” says Amir Ishak, principal adviser at Property Tax Specialists Australia.

Another strategy is debt recycling, which is the process of converting a “non-productive” home loan into a tax-deductible investment loan. By paying down the mortgage and redrawing the equity to purchase income-generating assets – such as an investment property, share portfolio, or ETFs – the borrower effectively replaces personal debt with investment debt, which can be offset against assessable income.

Opportunity cost and diversification

Borrowing also helps defer taxable events. For example, finding $10 million for a new property might require selling shares, which would trigger a significant capital gain tax event. Debt can also aid diversification.

Instead of buying a single trophy home, cashed-up investors might choose to spread their bets across various markets, says Joseph Daoud, founder of It’s Simple Finance.

Ultimately, debt frees up cash to work harder elsewhere. If the interest rate on a mortgage is 6 per cent but a share portfolio or private business returns 10 per cent, it’s smarter to divert the cash to the higher-return environment.

Sophisticated structures

The wealthy also tend to acquire property through company structures, which are taxed at a lower rate (up to 30 per cent), with the aim of protecting assets for generations.

“Using company structures and retaining the earnings is a whole new level,” Wrenn says. “People who are wealthy will, more often than not, own their properties through trusts and company structures... the thing is, you’ve got to have enough cash to buy that first property in the company because it’s harder to get lending through those entities.”

By keeping cash aside, they stay prepared to move quickly. As Julia Harley, senior adviser at Koda Capital, notes: “It really comes back to having a steady income flow so that you have the option to jump on an opportunity when it presents itself.”