March 16

Corporations. File the calendar year income tax return (Form 1120) and pay any tax due. If you want an automatic 6-month extension of time to file the return, file Form 7004, Application for Automatic Extension of Time To File Certain Business Income Tax, Information, and Other Returns, and deposit what you estimate you owe.

S corporations. File the calendar year income tax return (Form 1120S) and pay any tax due. Provide each shareholder with a copy of Schedule K1 (Form 1120S), Shareholder's Share of Income, Deductions, Credits, etc., or a substitute Schedule K1. If you want an automatic 6-month extension of time to file the return, file Form 7004 and deposit what you estimate you owe.

S corporation election. File Form 2553, Election by a Small Business Corporation, to elect to be treated as an S corporation beginning with the next calendar year. If Form 2553 is filed late, S corporation treatment will begin the following calendar year. For example, if you elect to be treated as an S corporation beginning the calendar year of 2015 and Form 2553 is filed late, the S corporation treatment will begin with the calendar year of 2016.

Electing large partnership. Provide each partner with a copy of Schedule K1 (Form 1065B), Partner's Share of Income (Loss) From an Electing Large Partnership, or a substitute Schedule K1. This due date applies even if the partnership requests an extension of time to file the Form 1065B by filing Form 7004.

September

September 10

Employees - who work for tips. If you received $20 or more in tips during August, report them to your employer. You can use Form 4070.

September 15

Individuals - Make a payment of your estimated tax if you are not paying your income tax for the year through withholding (or will not pay in enough tax that way). Use Form 1040-ES. This is the third installment date for estimated tax.

Corporations - File a calendar year income tax return (Form 1120) and pay any tax due. This due date applies only if you timely requested an automatic 6-month extension. Otherwise, see March 16.

S Corporations - File a calendar year income tax return (Form 1120S) and pay any tax due. This due date applies only if you timely requested an automatic 6-month extension. Otherwise, see March 16. Provide each shareholder with a copy of Schedule K-1 (Form 1120S) or a substitute Schedule K-1.

Partnerships - File a calendar year return (Form 1065). This due date applies only if you were given an additional 5-month extension. Otherwise see April 15. Provide each partner with a copy of Schedule K1 (Form 1065) or a substitute Schedule K1.

Corporations - Deposit the third installment of estimated income tax. A worksheet, Form 1120-W, is available to help you make an estimate of your tax for the year.

 October 

October 10

Employees - who work for tips. If you received $20 or more in tips during September, report them to your employer. You can use Form 4070.

October 15

Individuals - If you have an automatic 6-month extension to file your income tax return, file Form 1040, 1040A, or 1040EZ and pay any tax, interest, and penalties due.

Electing Large Partnerships - File a calendar year return (Form 1065-B). This due date applies only if you were given an additional 6-month extension. See March 16 for the due date for furnishing or substituting the Schedules K-1 to the partners.

 November

November 10

Employees - who work for tips. If you received $20 or more in tips during October, report them to your employer. You can use Form 4070.

Employees - Social Security, Medicare, and withheld income tax. File Form 941 for the second quarter. This due date only applies if you deposited the tax for the quarter timely, properly, and in full.

 December 

December 10

Employees - who work for tips. If you received $20 or more in tips during November, report them to your employer. You can use Form 4070.

December 15

Corporations - Deposit the fourth installment of estimated income tax. A worksheet, Form 1120-W, is available to help you estimate your tax for the year.