All Corporations, Limited Partnerships, Limited Liability Partnerships, and Limited Liability Companies must maintain a Registered Agent and Registered Address within a state. The registered agent is the legal representative and contact for the business. The registered agent cannot be the business entity itself. The registered agent may be a person or another formal business association which was incorporated (or qualified) in the state and which maintains a valid registered agent in thw state. A Post Office Box number is usually not sufficient.