If your business is a sole proprietor or single member LLC (or an LLC with two members that are spouses in a community property state) then your business income and expense activity is reported on your personal return using Schedule C, E, or F (depending upon the type of business) and a separate return is not required for the business.
But, if your business is a S Corp, Partnership or Multi-member LLC, then your business is required to file a separate return for the business entity. These types of returns can be prepared with TurboTax Business software.