CBO Director Douglas Elmendorf told the House Budget Committee on Thursday that the health care law will reduce employment by 0.5 percent by 2021 because some people will no longer have to work just to afford health insurance.

"That means that if the reduction in the labor used was workers working the average number of hours in the economy and earning the average wage, that there would be a reduction of 800,000 workers," Elmendorf said in an exchange with Rep. John Campbell (R-CA).

The report, published in August, said, "The Congressional Budget Office estimates that the legislation, on net, will reduce the amount of labor used in the economy by a small amount-roughly half a percent-primarily by reducing the amount of labor that workers choose to supply … That net effect reflects changes in incentives in the labor market that operate in both directions: Some provisions of the legislation will discourage people from working more hours or entering the workforce, and other provisions will encourage them to work more."