Is it time to fix your mortgage interest rate?

Choosing between a variable or fixed rate mortgage is always a gamble but by examining a range of economic variables it's possible to shift the odds in your favour, as this in-depth analysis from Investor Partner Group highlights.

Fixed rate vs variable rate mortgage sign next to model house.
Investor Partner Group provide an astute analysis of the variable versus fixed rate loans in the current economic environment. (Image source:

Should homeowners and investors fix their mortgage rate, given that the RBA is now set to raise the cash rate substantially over coming months?

The answer to that urgent question depends on another question – is inflation temporary, or will it continue?

If the economic factors driving the demand for goods and services up and driving supply down — such as high government spending, low interest rates, high commodity prices and supply chain issues — prove to be momentary, then inflation will soon peak and fall away. Borrowers who lock in the current, relatively high, fixed rate will then regret their choice.

Alternatively, if the current high consumer price index (CPI) figures flow into higher wages, causing high inflation to persist, then the Reserve Bank of Australia (RBA) will have to raise the cash rate to much higher levels to get on top of inflation. In that case homeowners and investors who fix now will be glad they did.


Before discussing inflation, let’s first work out how much the cash rate would have to rise to give fixed rate borrowers a better outcome than variable rate borrowers over a three-year period.

If over the next year the RBA steadily raises the cash rate from its current level of 1.35 per cent to 3.85 per cent then, by my calculations, interest payments on variable rate mortgages and fixed rate mortgages will be about the same over three years. If the cash rate goes higher than 3.85 per cent over the three years, then investors will have been better off if they fixed.


As an example, rates on mortgages fixed for three years are currently about 215 basis points (2.15 per cent) above variable rates. Three-year, fixed rate mortgages with a loan-to-valuation ratio (LVR) of 80 per cent for an owner-occupier paying principal and interest (P&I) are currently set at 5.39 per cent with ING. The same variable rate, with an offset account, is 3.24 per cent with Bendigo Bank. These figures are from on 1 August 2022.

The 2.00 per cent extra interest on a fixed rate mortgage is 6.00 per cent total extra interest over three years. Now imagine that the cash rate rises steadily by 1.50 per cent over the next year, from its current level of 1.35 per cent, and then settles at 1.35 + 2.5 = 3.85 per cent over the remaining two years. The variable interest rate would be 1.25 per cent higher in the first year (averaged over the whole year) than its current level, and 2.50 per cent higher over two more years, to give the extra 6.25 per cent over three years. I am assuming here that variable rates rise and fall in lockstep with the cash rate.

Will the cash rate reach 3.85 per cent?

Variable mortgage rates will depend on the RBA’s decisions on its cash rate, which will in turn depend on how the inflation rate evolves. CPI in the second quarter of 2022 was 6.1 per cent higher than a year ago, but the RBA is more concerned with core inflation (the trimmed mean) which was 4.9 per cent. We should expect the RBA to raise the cash rate meeting-by-meeting until core inflation is back under 3 per cent.

Will inflation fall back quickly or will it persist? The bond markets clearly think inflation will be temporary. We know what levels of future inflation the bond market is predicting because the Australian Federal Treasury raises money by issuing both regular bonds and inflation indexed bonds.

The only difference between these two types of bonds is that inflation indexed bonds have built in protection against inflation (the principal of the inflation indexed bonds increases each quarter with CPI). So, the difference in the yield on regular bonds and inflation indexed bonds is the expected inflation rate. Technically the difference in yields is how much bond investors are prepared to pay for inflation protection, but that is usually taken to be the same as expected inflation.

How much Australian dollar inflation is the bond market expecting in coming years? The bond market is expecting inflation to average 3.1 per cent over the next three years and then fall back to 2.0 per cent, which is the bottom of the RBA’s target range, and would make the RBA more inclined to cut rather than raise rates.

The corresponding bond market inflation expectations in the US are similar – inflation falling back quickly from its current high levels to 2.3 per cent within 18-24 months.

Bond market expects return of deflationary forces

The bond market clearly believes the current powerful inflationary forces in the US and Australian economies are only the result of short-term factors — mostly to do with Covid-19.

Soon, the powerful deflationary forces that have dominated the global economy for three decades before Covid appeared will reassert themselves. Those are the deflationary forces of: ageing populations; tech advances; globalisation of workforces; and concentration of wealth.

We should remember the state of play with inflation immediately before Covid struck.

In October 2019, fully three months before the first Covid death in Wuhan in January 2020, the RBA cut the cash rate to 0.75 per cent, which was then the lowest level ever. It cut rates, despite the strong growth in the Australian economy because of concern about growing deflationary pressures in the global economy.

The bond market believes that we will return to that world once Covid is in the rear vision mirror.

But price inflation could become entrenched in wage inflation

Some people argue that the deflationary force of ageing populations, tech advances, etc. are now much weaker since peak Covid.

The bond market clearly disagrees. Other, highly respected, market observers, such as Larry Summers, Mohammed El Erian and Noriel Roubini believe the bond market is underestimating the persistence of inflation. They point especially to the tightness of labour markets and the likelihood that inflation will become entrenched in wage rises.

It is generally agreed that if these predictions about wage inflation turn out to be right, then the US Federal Reserve and Australia’s RBA will have to take their short-term benchmarks well above the inflation rate to slow the economy, suppress wages and bring inflation back to below 3 per cent.

To flesh out that scenario, if price increases and wage increases fed off each other and became entrenched at above 3-4 per cent, then the RBA would have to take the cash rate to 4-5 per cent or more, and variable mortgage rates would go to 6.5-7 per cent. That unattractive prospect is not as likely as the bond market’s expected scenario of inflation falling back quickly, but it is a real possibility, nonetheless.

How to decide

Choosing between a variable or a fixed rate mortgage in the current circumstances comes down to whether the homeowner or investor can manage a much higher interest rate if that occurred.

If variable rates going to 5.5 per cent to 6 per cent would cause them real distress, then they should fix today. Otherwise, they should stick with a lower floating rate but keep an eye on whether wage increases are causing inflation to become entrenched.

Moxin Reza, is a Managing Director of Investor Partner Group, which provides wealth creation strategies using property as a vehicle over 30 years, data-driven buyers agency, property development, feasibility studies and TAX/SMSF advisory services.

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