If your mortgage rate exceeds your after-tax super return, paying down the mortgage wins mathematically. However, salary sacrificing into super also reduces taxable income — which changes the comparison. The right answer depends on your tax rate, mortgage rate, and years to retirement. Generally, if you're on a high marginal rate, super sacrifice wins.

HECS-HELP has no interest — it is indexed to inflation each 1 June (4.7% in 2024, 7.1% in 2023, 3.9% in 2022). If your investments are expected to outgrow inflation, investing typically wins. However, if your HECS balance is growing faster than your income or you find it stressful, voluntary repayments are reasonable.

A structured priority order: (1) Build a 3-month emergency fund. (2) Clear high-interest debt — credit cards and personal loans. (3) Consider voluntary HECS repayment if the balance is large. (4) Max out concessional super contributions up to the $30,000 cap. (5) Invest in a diversified ETF portfolio through a brokerage account.

Both serve different purposes. Savings (high-interest accounts, term deposits) provide security and liquidity — ideal for your emergency fund and short-term goals. Investments (shares, ETFs, property) offer higher long-term returns with more volatility — suited for goals 5+ years away. Fill your emergency fund first, then invest.