A registered agent is a responsible third-party who is registered in the same state in which a business entity was established and who is designated to receive service of process notices, correspondence from the Secretary of State, and other official government notifications, usually tax forms and notice of lawsuits, on behalf of the corporation or LLC.
If you do not have a physical location in the state in which your business is registered, you must designate a registered agent to accept documents on your behalf. The state in which your business is registered needs to know it has a contact person for your business within the state at all times; accordingly, PO boxes are not acceptable addresses for registered agents.
A registered agent accepts tax and legal documents on behalf of your business, making sure you don't miss important information regarding tax payments, lawsuits, or judgments involving your business; a registered agent may or may not have a role in the operation of the business itself.
Besides not worrying about missing important documents, having a registered agent also means that you will not have to accept potentially embarrassing legal and tax documents in front of clients. Another advantage is that, as your registered agent's address will remain the same, you can easily change your business location without necessarily having to file more paperwork to change your address with the state for each and every move.
A business that does not designate a registered agent may risk falling out of "good standing" with the state in which it is registered. Penalties can include license revocation, fines, and the inability to enter into legal contracts and/or gain access to the state court system. Moreover, reinstatement proceedings could include further monetary, civil, and possibly criminal sanctions as well.