If your LLC or corporation is new, there's something you may not have heard about. If your LLC or corporation operates outside your home state, you may have yet another bureaucratic hurdle to tackle: qualifying to do business in other states. The question of whether or not you need to qualify or register in other states depends on a number of factors, including whether the business you do in other states is considered "intrastate" or "interstate."
Qualification is fairly simple -- you file a form in each state you do business and pay a fee ($100 to $300), but the penalties for not doing so can be high. I just published an article on the subject in the Nolopedia, Nolo's encyclopedia of free legal information - check it out.