Administaff Inc. (NYSE: ASF), the largest PEO by revenue, said it doesn't yet know the ultimate impact federal healthcare reform legislation will have on its business, according to its 10-Q filing on Monday with the U.S. Securities and Exchange Commission. The company said several provisions in healthcare reform don't take effect for several years, and the legislation won't have a negative impact on operations in 2010.

Increased regulations can drive demand for its services, Administaff wrote in its 10-Q. "However, currently we are unable to determine the impact the act will have in future periods on the costs we will incur to comply with the act, our ability to match any resulting increased costs with pricing, our ability to attract and retain clients, our business model and our results of operations," according to its 10-Q.

The company said the legislation does provide a tax credit for small businesses that offer healthcare coverage to employees, but it's unclear whether PEO clients will be eligible.

"Based upon information contained in the Congressional Record, which specifically references professional employer organizations, we believe that these tax credits will be available to our clients that meet the qualification requirements," according to Administaff's 10-Q. "However, the act does not expressly address the issue of whether qualifying small business clients of a professional employer organization are entitled to the tax credits."