Federal corporate income tax
A corporation figures federal income tax by multiplying taxable income by 21% (Form 1120, Schedule J, line 1a). The return is generally due by the 15th day of the 4th month after the end of the corporation's tax year (with an exception for fiscal years ending June 30). Sales taxes are set by states and local governments; check your state. Reference: Internal Revenue Service (IRS), 2025 Instructions for Form 1120.