Auto insurance fraud cost the industry about $1.3 billion a year in Ontario, but the province "does not have significant measures in place to combat fraud," McCarter warned in his annual report.
The number of people killed or injured in auto accidents in Ontario fell 25 per cent in a decade, but the government still guarantees insurers a "reasonable rate of return" of 12 per cent. That figure was last adjusted in 1996, when the long-term bond rate it was based on was 10 per cent.
Finance Minister Dwight Duncan said the Ontario government would look at McCarter's recommendation to lower the 12 per cent guaranteed rate of return for insurers, but made no promises to cut the rate.
From 2005 to 2010, the total cost of injury claims rose 150 per cent, even though the number of injury claims in the same period increased only 30 per cent. The number of personal injury claims in 2009 was 20 per cent higher than the number of people who reported having been injured in an automobile accident that year.
"The commission that oversees the auto insurance sector does not know whether insurers are handling claims judiciously and paying out the proper amounts, and it needs better information on the impact of fraud on claim costs," McCarter wrote.
New Democrats said the province must do a better job over overseeing auto insurance providers.
"We've been saying for some time that insurance rates are over the top, unaffordable," said NDP Leader Andrea Horwath. "This report simply reinforces the fact that the auto insurance industry needs to be overhauled."