Interest rates are going up: Should you pay down your mortgage or buy ASX shares?

This simple calculation could provide the answer.

If you're among the 33% of Australians with a mortgage, you're likely to have noticed a dramatic increase in your mortgage repayments this year. 

Since the beginning of 2026, the Reserve Bank of Australia (RBA) has lifted the cash rate four times, taking it from 3.6% to 4.6%. This represents a 15-year high.

For those with an average $731,000 loan balance, this change is meaningful. For those with an even larger mortgage or insufficient income to cover it, the change is likely to be especially stressful. 

At the same time, a record number of Australians are investing.

According to the 2026 ASX Investor Study, 11.5 million Australians are now investing outside of their superannuation or primary residence in 2026. That's up by 2.5 million since 2020. 

The largest allocation is to ASX-listed shares, with 58% of investors holding them. 

Approximately 950,000 Australian adults also plan to start investing in the next 12 months.

Interest in Self-Managed Super Funds (SMSF) investing is also rising. Around 20% of non-SMSF investors say they're considering establishing an SMSF in the next 12 months.

Overall, the data is showing that a growing number of Australians are committed to growing their wealth through investing. However, in the face of mortgage pressures, many of these investors may be reconsidering whether to pay down the mortgage instead. 

While this is a highly personal decision, a simple calculation can help Australian mortgage holders decide which option is more likely to put them ahead.

So let's run through the numbers.

Motley Fool contributor Laura Stewart has no position in any of the stocks mentioned. The Motley Fool Australia's parent company Motley Fool Holdings Inc. has no position in any of the stocks mentioned. The Motley Fool Australia has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy. This article contains general investment advice only (under AFSL 400691). Authorised by Scott Phillips.

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