Businesses are only responsible for filing an income tax return on earnings once a year, but when the return is due is dependent on the company structure. Aside from income taxes, business have other tax filing requirements, including periodic reporting and deposit of the federal income taxes withheld from employee paychecks.
A corporation and a business partnership are different legal entities with similar methods of operation. Partners in a business partnership share equally in the responsibilities of maintaining the business and paying its debts.
A business becomes incorporated when the company's organizers file incorporation paperwork with the state. For example, corporations in Texas must file a certificate of formation with the Texas Secretary of State's office, as a condition of formation.