Every State, County and City will have different requirements
Below are some of the types of licenses that may be required:
Federal: Federal Tax ID Number: No fee required.
State: If your state collects sales tax, a sales tax permit is required from your state. Usually no fee. You will be responsible for collecting and transfering the sales tax to the state.
City: Most but not all cities may require a city business license. Usual cost is between $25 and $50.
The city may look at the type of business you have to see if it will work at that location. For instance, if you are working out of your home, will UPS and other truck deliveries or delivery of Oxygen tanks be a problen to the neighbors?