The Productivity Commission is expected to call for an overhaul of penalty rates in a final report into workplace relations due today.

The report is expected to recommend bringing Sunday penalty rates in some industries in line with time-and-a-half paid on Saturdays, reducing the overall pay.

This would include those in the entertainment, hospitality and retail industry, but not other workers, including emergency workers such as paramedics.

Unions and the Federal Opposition are gearing up for a fight, saying those who are forced to work on Sundays should not have their conditions cut.

Labor's workplace spokesman Brendan O'Connor urged the Government to reject the expected proposal.

"For so many workers it will mean a cut of up to 10 per cent of their income," he said.

"This is an attack on the lowest paid workers of Australia.

"Retail and tourist workers, hospitality workers, these people do not receive large amounts of money ... this will be a big blow for the household budget."

But business groups have said the move would help take the pressure off the retail and fast food sectors.

The Federal Government had previously downplayed any changes to Sunday penalty rates, saying it was a matter for the Fair Work Commission.

'Working weekends is a sacrifice'

Union group United Voice has fought to keep Sunday penalty rates.

National secretary Jo-Anne Schofield said retail and hospitality workers could not afford to take a pay cut.

"People in retail and hospitality are on modest earnings, so they can't afford to take a pay cut," she said.

"We estimate if the Productivity Commission's draft recommendation goes through, it would put some of our members back a couple of years.

"So they will be going back to what they were earning two years ago, and very few people can afford that, particularly people who are struggling at the bottom."

Hospitality worker Sharon Eurlings is one of thousands of people who sacrifice their weekends. She has a regular Sunday shift that starts at 4am.

"I miss out on a lot of sports with the kids, family days, Saturday nights where normal people have, I can't really make, I have to leave early or I just don't go," she said.

"There are a lot of sacrifices, but on the other hand as well, I can pick them up from school, which saves a lot of money for me for child care.

"The reason why I do the weekends is that it is extra money for me with my kids.

"I will have to do more hours — more time away from my kids, if I have to — to make it up somehow."

Australian Council of Trade Unions (ACTU) Secretary Dave Oliver said workplace conditions were under threat.

"We have been concerned for some time now that this Productivity Commission inquiry into the system will ultimately be the Trojan horse to bring back further IR reform, despite what this Government had been saying since they got elected," he said.

Penalty rates putting pressure on businesses

The retail industry has pushed for Sunday penalty rates to change.

Australian Retailers Association executive director Russell Zimmerman said businesses with retail stores throughout regional areas away from shopping centres were not opening on Sundays because they could not afford it.

"If penalty rates were reduced, we know that they would open," he said.

"We do know that if penalty rates were reduced, retailers would be prepared to put more staff on — in other words, pay the same kinds of wages now, but to employ more people.

"That's very important when you consider the high unemployment and particularly the high youth unemployment and retail uses all the young people."

The Government will hand down the final report in Perth later today.