If you are sole proprietorship, a business license is not usually necessary. However, once you make the change (and get some sort of tax benefit), a business license becomes necessary. Every state has its own rules for getting a business license and keeping it up to date.

If you are going the route where someone else takes care of the paperwork, most places will actually take care of getting the license squared away as part of setting up your home business. But you can do it yourself as well. Contact your city’s Chamber of Commerce, or your state Chamber of Commerce, and you will be pointed in the right direction.