Unions and Labor are sharpening their spears over industrial relations changes they say are the biggest attack on workers' rights since Work Choices.
Industrial Relations Minister Christian Porter introduced omnibus legislation on Wednesday to allow part-time employees to work extra shifts without the overtime rates.
As it stands, part-time workers in many industries are paid overtime for shifts they work outside their set hours. This means businesses have an incentive to hire casuals instead of permanent staff, the government has argued.
The bill also creates a statutory definition of a casual employee and gives them the right to ask to convert to a permanent job after 12 months.
If a court found a casual employee should have been classified as permanent, their 25 per cent loading should be subtracted from their overall claim.
It came after a landmark Federal Court ruling that casual staff who worked regular hours were entitled to be paid leave like full-time employees. It opened the door to billions of dollars in backpay.
But Mr Porter framed the bill as a way of reducing unemployment and underemployment.
"This is about more jobs, more hours, more ability to move from casual to permanent employment," Mr Porter said.
The bill creates a new criminal offence for systematic wage underpayments, with a maximum penalty of four years' jail and fines of up to $1.1 million for individuals and $5.5 million for companies.
Bosses convicted of wage theft would be disqualified from managing companies for five years.
The bill would also allow the Fair Work Commission to approve enterprise agreements that would make some workers worse off for up to two years.
Currently, the "better-off-overall-test" or BOOT requires the Fair Work Commission to assess whether employees will be better off under the new agreement than the award.
But under the changes, the commission could allow agreements that did not meet this threshold for businesses hard hit by the coronavirus pandemic, if both parties agree and the commission believes it is in the public interest.
The agreement will expire after two years.
Mr Porter said only a "handful" of businesses would benefit from the changes, which he described as "slight".
The law already allows the commission to consider agreements that don't meet the test during a short-term crisis.
Four such approvals were made when Labor was in power.
But Labor leader Anthony Albanese accused the government of using the pandemic as "cover" to cut workers pay.
"It's not just businesses who had a difficult year, workers have too," Mr Albanese said.
"Nurses, supermarket workers, cleaners, childcare workers, teachers, truck drivers, aged care workers, and all the frontline workers in Australia who have kept the nation running during this pandemic are being given a Christmas gift of a pay cut by this Prime Minister.
"The heroes of the pandemic deserve better than this Scrooge of a Prime Minister."
It's a theme Labor will continue on Thursday - the final sitting day of the year - and likely for months ahead, as the bill goes through a parliamentary inquiry.
It also means a return to the trenches for the Coalition and unions, who came together for more than 150 hours of roundtable meetings on industrial relations changes earlier in the year.
The collegiate way in which Mr Porter and Australian Council of Trade Unions secretary Sally McManus worked together in the early months of the pandemic spawned headlines like "When Christian met Sally: a match made by the pandemic". Mr Porter even referred to Ms McManus as his "BFF".
But Ms McManus said on Wednesday she'd been blindsided by parts of the bill and the government had moved away from the "middle ground".
She said the trade union movement would fight "as hard as necessary" to stop the changes.
"It's the worst thing since Work Choices," she said.
"Once you open the door to having some employers go below what the minimums are, you put pressure on every other employer to do the same, it's a race to the bottom. That's just basic economics.
"Work Choices was less than 18 months and we've still got Work Choices zombie agreements 13 years on.
"We just don't want another wave of zombies we have to deal with."
Prime Minister Scott Morrison accused Labor of believing "jobs would create themselves".
"The Labor Party wants to stand in the way of Australians getting jobs," Mr Morrison said.
It came as new data from the Australian Bureau of Statistics showed the number of people with jobs rose to 12.9 million.
The number of secondary jobs jumped by 135,700 in the September quarter.