When the Reserve Bank of Australia raises the cash rate, the standard expectation is that borrowing becomes more expensive, households spend less, and inflation eases. This mechanism worked reliably through the tightening cycles of the 1980s and 1990s. There is growing evidence, however, that the same lever now produces a weaker and more uneven effect, not because the tool has changed, but because the population it acts on has.
The core reason is demographic. Australia’s population has aged substantially since the era when interest rate policy was most effective. The balance between mortgage-holding, income-earning households who feel the pinch of higher rates, and mortgage-free, savings-holding retirees who benefit from them, has shifted materially. Understanding that shift helps explain both why inflation proved so persistent through the post-2022 tightening cycle, and why the same challenge is likely to intensify in the decades ahead.
How rate hikes are supposed to work
The mechanism is straightforward. When the RBA raises the cash rate, variable-rate mortgage repayments increase directly. A household with a $650,000 variable-rate mortgage faces approximately $100 in additional monthly repayments for every 25 basis point increase. Multiplied across hundreds of thousands of mortgaged households, this reduces disposable income, dampens consumer spending, and takes pressure off prices.
In Australia of the 1980s, this worked swiftly and substantially. The postwar baby boom had produced a large working-age population. They were employed, mortgaged, and paying income tax. A rate rise hit them squarely. The RBA raised rates and spending fell. The relationship was relatively predictable.
The other side of the equation
There is, however, a second type of household in the economy: the retired, mortgage-free household living on superannuation savings and term deposit income. For this household, a rate increase does not raise costs, it raises income. When the cash rate goes up, so does the interest paid on savings accounts and term deposits. A retiree holding $400,000 in deposits may see several thousand dollars in additional annual income following a tightening cycle.
With no mortgage repayments and no tax payable on superannuation income in the pension phase under current Australian law, that additional interest income flows largely into discretionary spending. The household that was supposed to pull back instead has more to spend.
This is not a new observation in isolation. The issue is what happens when this second household type grows significantly as a share of the total population, which is precisely what has occurred over the past four decades.
A population that has changed profoundly
In 1983, Australia’s median age was 29.6 years and the vast majority of the population was of working age, carrying mortgages, paying income tax, and directly exposed to the cost of borrowing. Australians aged 65 and over represented approximately 9 per cent of the total population, according to ABS data.
By 2026, the median age has risen to approximately 38.5 years. The over-65 cohort now accounts for around 16.5 per cent of the population, approximately 4.3 million people, compared with 1.8 million in 1983. The ABS projects this will reach 22 per cent by 2057. Over the same period, the share of the population aged under 45 has fallen from around 78 per cent to 68 per cent.
This is not a temporary fluctuation. It is the predictable consequence of the postwar baby boom working its way through the age structure of the population. The boomers who once formed the core of the mortgage-holding, rate-sensitive cohort have retired. They have paid off their homes. Their financial relationship with interest rates has reversed.
By 2057, the over-65 cohort is projected to reach 22% of Australia’s population. The cohort that gains from rate hikes is growing. The cohort constrained by them is shrinking.
What the data is already showing
This isn’t just theoretical. During the 2022–23 tightening cycle, Commonwealth Bank spending data showed Baby Boomers, who make up more than 27 per cent of Australia’s adult population, increased their spending on dining out by 7 per cent and travel by 10 per cent, even as younger, mortgaged households pulled back. Separately, ABS Census data shows 61.9 per cent of Australians aged 60 and over own their homes outright, giving the majority of that cohort no mortgage exposure whatsoever.
The tax dimension
The divergence between these two household types is reinforced by Australia’s tax settings. Working-age households pay marginal income tax on wages, contribute 12 per cent of ordinary earnings to superannuation under the Superannuation Guarantee, and where applicable, make HECS-HELP repayments. A significant share of each dollar of gross income simply does not reach discretionary spending.
Retirees drawing income from superannuation in the pension phase pay no tax on those earnings under current law. The Seniors and Pensioners Tax Offset can further reduce or eliminate tax liability on additional income. When a rate rise increases a retiree’s deposit income, more of each additional dollar reaches their wallet, and is available to spend.
When the RBA raises rates, it therefore applies financial pressure to a cohort that is shrinking as a share of the population, while providing a tax-advantaged income boost to a cohort that is growing. The net drag on consumer spending is smaller than it would have been in the 1980s, when the indebted, working-age cohort dominated.
Age distribution: 1983, 2026 & 2057
The chart below uses ABS historical population data for 1983 and 2026, alongside ABS population projections published in 2023 for 2057, to show how Australia’s age structure has already shifted and where it is headed. The steady expansion of the 60-and-above cohorts — and the relative decline of those aged 25–44 — illustrates how the population that rate increases act on today looks very different from the 1980s, and will look different again by mid-century.
Sources: Australian Bureau of Statistics — National Population Projections (2023); Historical Population Data, Cat. No. 3101.0.
A structural shift, not a cyclical one
What makes this different from other factors that slowed the recent tightening cycle is that it is structural and continuing. Each passing year, a larger share of the population sits on the savings side of the interest rate equation. The trajectory is well established and will not reverse.
Research from the Bank for International Settlements points to declining sensitivity of household spending to interest rate changes in economies with older population profiles, including Japan and Germany, countries further along the same demographic curve Australia is now on. Closer to home, the RBA’s own research acknowledges that the mix of household balance sheets across the economy affects how reliably rate changes flow through to changes in consumer spending.
This does not mean interest rate policy has become ineffective. Rate increases still constrain new borrowing, affect asset prices, and raise the cost of credit. But the degree to which each rate increase reduces overall consumer spending is likely smaller than it was forty years ago, and is likely to become smaller still in the future.
Summary
The interest rate tool the RBA uses today is the same one it used in the 1980s. The population it acts on is not. A growing share of Australians have moved past the mortgage-holding, income-taxed, rate-sensitive phase of their financial lives. For that cohort, higher rates are not a constraint on spending, they are a source of additional income.
This does not diminish the role of monetary policy. But it does suggest the relationship between the cash rate and inflation is evolving alongside Australia’s age structure and that understanding this shift matters both for reading past tightening cycles and for setting expectations around future ones.
This analysis draws on publicly available ABS, RBA, BIS, and CBA data. It does not assess the appropriateness of current RBA policy settings, nor does it constitute financial or investment advice.
Written by Andrew Whelan, General Manager – AP Group
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About the Author:
When Andrew Whelan is not out pedalling his bike or looking after his two marvellous kids, he’s pedalling through pharmacy finance and strategy development.
Having been with AP Group since the beginning, Andrew has more than a decade experience in pharmacy and is an asset to the sales and finance division. He’s a numbers wizard, people person and sustainability champion — leading AP Group to achieve official Carbon Neutral Certification with Climate Active.
Before AP Group, Andrew spent more than a decade in the telecommunications and media industry including 7 years at Telstra in a variety of senior management roles and 3 years in the United Kingdom managing the commercial function for the British Sky Broadcasting — a time where it was the fastest growing broadband provider in the UK.
So it’s no surprise that he is well equipped to help customers with some of the biggest decisions they will ever make — buying a home or investing in a pharmacy — and helping to show them what’s truly possible.