Individuals: File a 2015 income tax return. (If you are a resident of Massachusetts or Maine, Patriots’ Day [April 18] delays the due date for filing your income tax return until April 19.) If you want an automatic six-month extension of time to file the return, file Form 4868, Application for Automatic Extension of Time To File U.S. Individual Income Tax Return. Then, file Form 1040, 1040A, or 1040EZ by October 17. If you are not paying your 2016 income tax through withholding (or will not pay in enough tax during the year that way), pay the first installment of your 2016 estimated tax. Use Form 1040-ES.

Employers: For Social Security, Medicare, withheld income tax, and nonpayroll withholding, deposit the tax for payments in March if the monthly rule applies.

Household Employers: If you paid cash wages of $1,900 or more in 2015 to a household employee, file Schedule H (Form 1040) with your income tax return and report any household employment taxes. Report any federal unemployment (FUTA) tax on Schedule H if you paid total cash wages of $1,000 or more in any calendar quarter of 2014 or 2015 to household employees. Also report any income tax you withheld for your household employees.

Partnerships: File a 2015 calendar-year return (Form 1065). Provide each partner with a copy of Schedule K-1 (Form 1065), Partner’s Share of Income, Deductions, Credits, etc., or a substitute Schedule K-1. If you want an automatic five-month extension of time to file the return and provide Schedule K-1 or a substitute Schedule K-1, file Form 7004. Then, file Form 1065 by September 15.

Electing Large Partnerships: File a 2015 calendar-year return (Form 1065-B). If you want an automatic six-month extension of time to file the return, file Form 7004. Then, file Form 1065-B by October 17.

Corporations: Deposit the first installment of estimated income tax for 2016.