Not all states require a license to administer a tattoo, but most have some requirements that must be met before a person is allowed to tattoo someone. A large number of states have deemed it illegal to tattoo a person without a state-administered license.
Some states require that an establishment, and the tattoo artist, apply for a license before being allowed to administer tattoos. In many states, it is also illegal to apply tattoos in places outside of the licensed location. Penalties for tattooing without a license also differ within states, but the crime is usually a misdemeanor offense punishable by fines and possible jail time.