Our firm experiences this all the time. As a specialty design firm we work all over the country. Between me and my partners we're registered in 46 states, DC, and previously two Canadian provinces. What we've learned is each location has unique rules. Some states require a professional firm registration in addition to the individual, some also have business license requirements. Some counties, cities, and towns do too. Last year we filed tax returns in 23 localities. What we've learned is that before working in a place for the first time we define regulatory requirements. If they are substantial and the project small we decline the work. We average those expenses and add it to the overhead component of our fees.