A provision in President Obama's health care reform plan that requires businesses to offer health insurance to their workers or face a federal tax would cost employers at least $49 billion dollars a year, putting 5.2 million employees at risk of unemployment or underemployment, according to a new study.

"Health care reform is not going to be free," said economist Mark Wilson, who authored the study, which was commissioned by the conservative Heritage Foundation.

Under the provision, known as the play-or-pay mandate, another 10.2 million employees will face stunted wages and the loss of their benefits as employers try to find ways to fund the mandates...