In an annual report, WellPoint said its medical costs rose 8.9 percent last year, the Indianapolis Star reported Thursday.
But some customers said their bills jumped nearly 40 percent recently, the newspaper said.
Perry Snow, a retiree from South Bend, Ind., said WellPoint has informed him his monthly bills would rise from $280 per month to $387.49 per month.
He also said, "you don't have any choice. If you have any breaks in coverage, you pay dearly for it."
Recently, the California Department of Insurance said it would hire an auditor to review the company's books after monthly premiums went up 39 percent, the Star reported.
In Indiana, "if a company demonstrates through actuarial analysis that the benefits provided require an increase in excess of 30 percent, such increase must be approved," said Doug Webber, lead attorney for the Indiana Department of Insurance.
WellPoint spokeswoman Kristin Binns said, "we understand our members' concerns about these increases, which underscore the need for effective health-care reform that addresses the underlying problem of soaring medical costs."
Copyright 2010 United Press International.