Workers were underpaid $24.4 billion across five years between 2018 and 2023, according to the latest Australian Taxation Office data analysed by the industry group Super Members Council.
NSW had the highest value of underpayments over the five years, totalling an eye-watering $8.1 billion, followed by Victoria ($6.1 billion) and Queensland ($4.7 billion).
The impact of underpayment intensifies over a person's working life.
Some $1730 in missed super in one year could potentially leave someone $30,000 poorer at retirement due to lost compounding of investment returns.
"Unpaid super hits hardest where it hurts most - for women, younger workers and people on low incomes," council chief executive Misha Schubert said.
Women already retire with 25 per cent less retirement savings than men, according to the Association of Superannuation Funds of Australia.
Young workers and low-income earners were also at risk of underpayment, with one in every two people on less than $25,000 missing unpaid super.
"This is money Australians have earned but never been paid - and it's leaving millions significantly poorer at retirement," Ms Schubert said.
Workers in the Northern Territory were the worst impacted, underpaid an average of $2140 in super entitlements each year, followed by the ACT ($2120), and Western Australia ($1800)
From July 1, payday super laws will come into effect, requiring employers to pay superannuation contributions within seven days of paying wages.
Super funds will have three business days to allocate or return the contributions, improving transparency for workers.
The reform would be a game-changer for unpaid entitlements, Ms Schubert said.
"This long-overdue shift to pay super with wages will make any underpayments visible, easier to fix, and far harder to hide," she said.
For its part, the tax office plans to take a pragmatic approach to compliance during the first 12 months of the reforms.
"Employers who make an honest mistake and take steps to fix it quickly won't be the focus of ATO compliance action in the first year," tax office deputy commissioner Emma Rosenzweig said.
Almost half of businesses already pay superannuation more frequently than quarterly, as currently required.
"It's important to plan ahead - review and check with your payroll provider about readiness to pay super guarantee more frequently, and start transition planning early," Ms Rosenzweig said.
However, real-time super payments could put pressure on businesses already under financial strain, according to insolvency and business recovery specialist Jirsch Sutherland.
"In effect, super has operated like a 'buy now, pay later' mechanism for some businesses – and that flexibility is about to disappear," partner Chris Baskerville said.
Sectors with high payroll costs and tight margins would likely face greater pressure.
"These are industries with very little margin for error," Mr Baskerville said.
"When super has to be paid every cycle, there's far less capacity to absorb uneven or seasonal cash flow."
As of the end of 2025, Australians had a total of $4.5 trillion in super.
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