The U.S. Office of Special Counsel has released a detailed memo that outlines how the Hatch Act affects certain federal, state and local government employees (check here to see if you fall into this category.) Specifically, the memo addresses social media and identifies acceptable and unacceptable online activities for covered employees on social media platforms such as Twitter, Facebook and personal blogs. Covered employees can, for example, advocate for a political candidate or group through their Facebook status updates; however, employees cannot post links to the "contribution page" of a political site.
It's imperative that covered employees know which political activities they can and cannot engage in online, whether at work or at home: penalties range from a written warning to termination. OhMyGov! has created this very handy guide.