Should I put extra money into super or my mortgage offset?

It depends on your mortgage interest rate, expected super returns, marginal tax rate, and time horizon. Mortgage offset gives a guaranteed tax-free return equal to your interest rate. Super grows at investment returns but contributions are taxed at 15% and funds are locked until preservation age. Generally, super wins over longer horizons if returns exceed the mortgage rate.

What is the effective return from a mortgage offset account?

The effective return from a mortgage offset equals your mortgage interest rate, and it is tax-free (since you're reducing interest rather than earning income). For example, a 6.5% mortgage gives an effective after-tax return of 6.5%, which is equivalent to earning about 9.6% in a taxed investment for someone on the 32.5% marginal rate.

Why is super locked up until preservation age?

Super is a long-term retirement savings vehicle. The government restricts access until preservation age (60 for most people) and a condition of release is met, such as retirement. This illiquidity is a key trade-off when comparing super versus accessible investments like offset accounts.

Does salary sacrifice affect this comparison?

Yes significantly. Salary sacrifice contributions are taxed at only 15% instead of your marginal rate, which boosts the effective return on the super option. For someone on the 37% marginal rate, a 7% super return effectively becomes around 8.8% after accounting for the concessional tax saving.

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Super vs Mortgage Offset Calculator

Compare the wealth-building power of extra super contributions against putting the same money into your mortgage offset account.

Amount Available per Year

Mortgage Interest Rate (%)

Expected Super Return (%)

Your Marginal Tax Rate

19% 32.5% 37% 45%

Years to Compare

Better Strategy

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Super After-Tax Return

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Mortgage Effective Return

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Super Value After N Years

Offset Value After N Years

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Super vs Mortgage Offset — Key Considerations

This is one of the most common financial planning questions for Australians with both a mortgage and the ability to make extra super contributions. The answer depends on several factors, and often the right answer is a combination of both strategies.

The Mortgage Offset Advantage

Money in an offset account reduces your mortgage interest dollar-for-dollar. The return is guaranteed and tax-free — you don't pay income tax on interest saved (unlike interest earned in a savings account). For a 6.5% mortgage, this is a risk-free 6.5% after-tax return. It also keeps your money accessible if you need it for emergencies.

The Super Advantage

Super contributions (especially salary sacrifice) are taxed at only 15%, giving a significant boost versus your marginal rate. Investment returns inside super are also taxed at just 15% in accumulation phase (and tax-free in pension phase from age 60). Over long investment horizons, the compounding effect in super's concessional tax environment can outweigh the guaranteed mortgage return.

The Liquidity Trade-Off

The key drawback of super is access. Funds are locked until preservation age (60 for most). If you're in your 30s or 40s and might need the money before retirement, the mortgage offset is more flexible. If you're in your 50s and won't need the funds until retirement, super is generally superior.

A Combined Approach

Many financial advisers recommend a hybrid strategy: maintain a comfortable buffer in the offset account (3–6 months of expenses), then direct extra funds into super via salary sacrifice to maximise the tax benefit and long-term growth.

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Frequently Asked Questions

What if my mortgage rate is higher than my super return?

If your mortgage rate exceeds your expected super return net of tax, the offset account wins on a pure numbers basis. However, remember that salary sacrifice contributions receive a tax saving at your marginal rate, which effectively boosts the net super return. The break-even point is closer than it looks at first glance.

Does paying off my mortgage faster affect borrowing power?

Reducing your mortgage balance increases equity but paying down the principal directly doesn't typically improve your borrowing power for new loans (lenders assess serviceability on income). An offset account keeps the same flexibility — your mortgage balance is unchanged, but the interest is offset, and you can redraw from the offset at any time.

Can I do both simultaneously?

Absolutely. You can salary sacrifice into super while also making extra offset deposits. Many people split their available funds — for example, half into salary sacrifice (for the concessional tax benefit) and half into the offset (for liquidity and guaranteed return). The right split depends on your age, income, risk tolerance, and financial goals.

How does this change as I approach retirement?

As you near retirement age, the liquidity disadvantage of super diminishes. Once you're within 5–10 years of preservation age, maximising super contributions via salary sacrifice typically becomes the better strategy, as you'll be able to access the funds soon and the tax benefits are substantial.

Disclaimer: This calculator provides illustrative comparisons based on simplified assumptions. Super contributions are subject to preservation restrictions until age 60. Investment returns are not guaranteed. The super value shown does not deduct fund fees or earnings tax. This is not financial advice. Consult a licensed financial adviser before making contribution decisions.

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Super vs Mortgage Offset Calculator

Super vs Mortgage Offset — Key Considerations

The Mortgage Offset Advantage

The Super Advantage

The Liquidity Trade-Off

A Combined Approach

Frequently Asked Questions

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