Individuals

• Form 1040 or Form 1040-SR. This form is due on the 15th day of the 4th month after the end of your tax year. Form 4868 is used to request an automatic 6-month extension of time to file Form 1040 or Form 1040-SR.
• Estimated tax payments (Form 1040-ES). Payments are due on the 15th day of the 4th, 6th, and 9th months of your tax year and on the 15th day of the 1st month after your tax year ends.

Partnerships

• Form 1065. This form is due on the 15th day of the 3rd month after the end of the partnership's tax year. Provide each partner with a copy of their Schedule K-1 (Form 1065) or substitute Schedule K-1 (Form 1065) and, if applicable, Schedule K-3 (Form 1065) or substitute Schedule K-3 (Form 1065) by the 15th day of the 3rd month after the end of the partnership's tax year. Form 7004 is used to request an automatic 6-month extension of time to file Form 1065.

Corporations and S Corporations

• Form 1120. This form is due on the 15th day of the 4th month after the end of the corporation’s tax year. However, a corporation with a fiscal tax year ending June 30 must file by the 15th day of the 3rd month after the end of its tax year. A corporation with a short tax year ending anytime in June will be treated as if the short year ended on June 30, and must file by the 15th day of the 3rd month after the end of its tax year. Form 7004 is used to request an automatic 6-month extension of time to file Form 1120. However, corporations with a fiscal tax year ending June 30, or a short tax year treated as if the short year ended June 30, will use Form 7004 to request an automatic 7-month extension of time to file Form 1120.
  
• Form 1120-S. This form is due on the 15th day of the 3rd month after the end of the corporation's tax year. Provide each shareholder with a copy of their Schedule K-1 (Form 1120-S) or substitute Schedule K-1 (Form 1120-S) and, if applicable, Schedule K-3 (Form 1120-S) or substitute Schedule K-3 (Form 1120-S) by the 15th day of the 3rd month after the end of the corporation's tax year. Form 7004 is used to request an automatic 6-month extension of time to file Form 1120-S.
• Estimated tax payments. Payments are due on the 15th day of the 4th, 6th, 9th, and 12th months of the corporation's tax year.
• Form 2553. This form is used to choose S corporation treatment. It is due no more than 2 months and 15 days after the beginning of the tax year the election is to take effect or at any time during the preceding tax year.