If you have a business that does business in states, other than where the company was set up, you should typically register them as foreign corporations in that other foreign state. It allows the states to know that you’re there, it gives them taxing rights, and if you have employees in that state, it gives them the ability to get an employment insurance in the state where they work. You should consult an attorney about whether it’s appropriate to file for foreign corporations or entities in another state.