- What interest rate should I use for Australia?
- It depends on the investment. High-interest savings accounts track the RBA cash rate; check Canstar or RateCity for current rates as they change with each RBA decision. Term deposits sit in a similar range for 1–2 year terms. The ASX 200 has returned approximately 9–10% p.a. total (dividends plus capital growth) over the long run, though with significant year-to-year volatility. Balanced super funds typically return 6.5–7.5% after fees and tax over the long term. Use 7% as a conservative base for a long-term diversified equity portfolio.
- Does compounding frequency really make a significant difference?
- On a savings account, the difference between daily and monthly compounding is small, less than 0.1% of the balance per year. On $500,000, that is still $500 per year, which adds up. For equity investments, formal compounding frequency matters less because returns are driven by market movements, not a stated rate, though reinvesting dividends (DRIP) creates a similar compounding effect. The biggest variable is always the annual return rate, not the compounding frequency.
- How much do I need to save per month to reach a target amount?
- Work backwards from your goal. To reach $500,000 in 20 years at 7% p.a. starting from $0, you need roughly $1,080 per month. Starting with $50,000 reduces that to about $760 per month, showing how an upfront lump sum significantly reduces the ongoing burden. Use this calculator by adjusting the monthly contribution until the final balance reaches your target. For a more targeted approach, try the Savings Goal Calculator.
- Which Australian accounts actually compound interest?
- Most high-interest savings accounts compound daily. Term deposits typically pay interest at maturity or annually, making them effectively simple interest for a given term. ETFs do not pay a stated interest rate, but price growth and dividend reinvestment create compounding returns over time. Super funds reinvest earnings annually within a concessional 15% tax environment.
- How does compound interest compare to simple interest?
- $10,000 at 7% p.a. for 20 years: with simple interest you earn 7% × $10,000 × 20 = $14,000, ending with $24,000. With compound interest (annual), the same investment grows to $38,697 — $14,697 more. At 30 years, compounding produces $76,123 versus $31,000 simple, a $45,123 difference on the same original $10,000. The longer the time horizon, the more dramatic the compounding advantage.
- When does compound interest really start to accelerate?
- Compound growth follows a hockey-stick curve (slow in the early years), then sharply accelerating. On a $10,000 investment at 7%, the first decade adds $9,672 in interest. The second decade adds $19,584, more than double. The third adds $39,616 (double again). This doubling pattern is why financial advisers consistently emphasise starting early, even with small amounts. The last five years of a 30-year investment can generate more growth than the first 15 years combined.
- How does compound growth work in superannuation?
- Super is one of Australia's most powerful compounding vehicles because of its low tax environment: contributions are taxed at 15% (versus your marginal rate), and earnings inside super are taxed at 15% during accumulation and 0% in pension phase. A 25-year-old contributing $500/month for 40 years at 7% p.a. accumulates approximately $1.3M inside super. The same gross return held outside super produces a materially smaller balance because investment earnings face marginal tax rates rather than the 15% super rate. Over four decades, that difference compounds substantially.
- Is the interest I earn in a savings account taxable in Australia?
- Yes. Interest earned in Australian savings accounts and term deposits is taxable income and must be declared on your annual tax return. It is taxed at your marginal rate — there is no 50% CGT discount, as that applies only to capital gains on assets held over 12 months. Banks report interest paid to the ATO, so it is usually pre-filled in your myTax return. If your HISA pays 5% and your marginal rate is 32% (30% income tax + 2% Medicare levy), your effective after-tax return is approximately 3.4%. This is why the tax efficiency of super, where earnings are taxed at just 15%, makes it increasingly valuable for long-term savings.