What is Form 1040?
Definition Form 1040 is the standard U.S. individual income tax return used to report a person's income, deductions, and credits and to calculate the tax owed or refund due. Most other tax forms and schedules, such as Schedule C or Schedule K-1, ultimately feed into it. Nearly every individual taxpayer files a version of this form each year.
It is the central document of individual tax filing, so almost every planning strategy and source document a client provides eventually shows up here.