You can continue operating as a sole proprietor as long as you're the only owner of the business. Establishing a sole proprietorship is cheap and relatively uncomplicated. If you're going to conduct your business under a trade name such as Smith Furniture Store rather than John Smith, you'll have to file an assumed name or fictitious name certificate at a local or state public office. This is so people who deal with your business will know who the real owner is. In addition, you may have to obtain a business license to do business under state laws or local ordinances.
States differ on the amount of licensing required.
In California, for example, almost all businesses need a business license, which is available to anyone for a small fee. In other states, business licenses are the exception rather than the rule. But most states require a sales tax license or permit for all retail businesses. Dealing with these routine licensing requirements generally involves little time or expense. However, many specialized businesses such as an asbestos removal service or a restaurant that serves liquor require additional licenses which may be harder to qualify for.