The federal opposition wants parliament to restore Sunday penalty rates for up to 700,000 Australians.
Labor leader Bill Shorten introduced legislation to the lower house on Monday that he says could protect incomes from July 1.
"We know that penalty rates are not a little bit extra, not just the cream on the cake - penalty rates help people put food on the table and petrol in the car," Mr Shorten said.
If Australia wants to have a seven day a week 24-hour economy there's always a worker making that happen, he said.
Mr Shorten said with this legislation before parliament at the same time as the government's company tax bill it was a critically important week in the life of this parliament, calling the bills the starkest test of the government and opposition's priorities.
"This week the Australian people will find out if its parliament is prepared to back in legislation giving $80 billion away, principally to the top end of town, whilst at the same time refusing to protect the penalty rates of hundreds of thousands of Australian workers," he said.
The Fair Work Commission cut Sunday penalty rates for hospitality, retail, pharmacy and fast food employees from July 1 last year.
The decision was backed by the Federal Court after a union challenge, but a Senate inquiry report last October called for it to be overturned.
The Turnbull government rejected the proposal, accepting the independent umpire's call.
Workplace Minister Craig Laundy took aim at Mr Shorten over his time as national secretary of the Australian Workers Union, saying he'd stripped a group of workers of penalty rates in 2006.
"Labor now pretends to be outraged when the independent umpire, which it set up, is making it fairer for small business by reducing Sunday penalty rates in just four awards," he said.
Australian Associated Press