The IRS is preventing loop holes for Health Care Reform rules
In anticipation of many employers attempting to use staffing agencies to have an employee's hours split up between several differing "employers" to prevent an employee from being classified as a full-time employee, there have been some anti-abuse provisions put into place. Under these provisions, if an employee provides services to an employer directly as well as through a staffing company, all hours of services will be attributed to the employer.
Also, employers must apply a good-faith determination while classifying employees as seasonal that is consistent with the Department of Labor Guidelines. More than likely, there will be more specific guidelines pertaining to the classification of seasonal employees later this year that will go into effect 2014 or 2015.