A daylight saving time glitch means thousands of Australians employed in hospitals, service stations, fast food restaurants and warehouses will work for free for 60 minutes on Easter Sunday.
Easter Sunday will be 25 hours long for NSW, Victoria, South Australia, Tasmania and the ACT, where 2.59am is followed by 2am again as the clocks roll back for winter.
But many overnight workers won't see this reflected in their pay slips because they work "by the clock", meaning their pay is determined by when their shift starts and ends, not hours worked.
This means someone clocking in at 10pm and finishing at 6am will have worked nine hours due to daylight saving, but will only be paid for eight.
More than one million Australians work in after-dark industries, according to research by the University of Melbourne.
Some enterprise agreements made up for the extra hour, Retail and Fast Food Workers Union spokesman Josh Callinan said.
But paying "by the clock" was the default arrangement and much more common, he said.
The award covering Australia's 14,000 service station staff, for example - a major overnight workforce - specifies daylight saving does not entitle employees to an extra hour of pay.
"I recall the concern when I worked overnight in service stations in the 1990s," Mr Callinan told AAP on Thursday.
"We do encourage all employers to pay workers for the time they actually work."
Reserve Bank security guards and Victorian public mental health workers are among the few paid for every minute they work when clocks move for daylight saving.
Easter is a public holiday everywhere daylight saving occurs except Tasmania, compounding the impact on those who might otherwise enjoy penalty rates.
While employees working "by the clock" get an extra hour's pay when daylight saving time begins in October, that day is not a public holiday.
And there was no guarantee the same employee would work at both ends of daylight saving, Mr Callinan said.
"The wage does not balance out since it is often a different worker," he told AAP.
"Some are short-changed lawfully."
The Albanese government referred questions to the Fair Work Ombudsman which said it was unable to comment on policy.
The short-change comes as the government threw its weight behind pay increases for low-wage and award-reliant workers in its submission to the annual wage review on Thursday.
"Low-paid workers are more exposed to financial shocks and they experience greater financial hardship, and we support lifting their wages," Employment Minister Amanda Rishworth said.
