The party plans to introduce a bill that would eliminate performance pay in any future contracts, NDP Leader Andrea Horwath said Monday.
It's wrong to hand out bonuses to top civil servants and executives in the broader public sector when the government is demanding a wage freeze from rank-and-file workers, she said.
"When 98 per cent of the managers are getting a bonus it's obviously more to do with an annual increase under a different name," she said.
"The government likes to talk the talk about freezing, but ... some people are frozen more than others and it's just inappropriate."
The Liberals say they want to clamp down on compensation to help eliminate Ontario's $15-billion deficit, yet they're spending millions on performance pay, she said.
"If we're going to freeze let's freeze everybody and let's not continue to allow these management salaries and CEO salaries spiral out of control," Horwath said.
Her comments come after The Canadian Press reported that nearly all eligible managers in the Ontario Public Service were awarded bonuses last year, costing $35.6 million.
Greg Reed, the CEO of eHealth Ontario, also returned his $81,250 bonus after The Canadian Press reported it.
Some would argue that performance pay helps attract and retain talent in the province, but Howarth said that's a "self-fulfilling" argument.
Hospital executives in provinces like British Columbia and Manitoba are making about half of what some are paid in Ontario, she said.
"So you can't tell me the CEO of a major regional hospital in B.C. or Manitoba is somehow doing less work or has less skills or requires less capacity than someone in Ontario doing the exact same job," she said.
The issue appears to have united parties on the left and the right, with the Progressive Conservatives piling on the Liberals for spending money when everyone's tightening their belts.
But they won't say whether they'll join forces with the NDP to pass the bill in the legislature.
"There are individuals, I'm sure, who are worth some bonuses," said Tory Rob Milligan. "But ... we need to see results."
The bonuses have come back to haunt the governing Liberals, who have engaged in a very public fight with teachers and doctors in their efforts to curb compensation.
Critics say the bonuses will damage the Liberals' chances of getting a pay freeze in upcoming labour negotiations with other groups.
Premier Dalton McGuinty has promised to review the performance pay system, saying it doesn't seem to be working the way it should.
Government house leader John Milloy, who announced Monday that the legislature would come back Aug. 27, wouldn't say whether the Liberals would support the NDP's bill.
"I certainly have a lot of faith in the action that our government has taken in a whole variety of areas to make sure that we have fair and equitable salaries and pay when it comes to the public service and broader public service," he said.