January 31, 2019. Individuals.
File your income tax return (Form 1040) for 2018 if you didn’t pay your last installment of estimated tax by Jan. 15. Filing your return now prevents any penalty for late payment of the last installment.

January 31, 2019. Employers.
Give your employees their copies of Form W-2 for 2018.
File Form W-3 along with Copy A of all the Form W-2s you issued for 2018.
Applicable Large Employers under the affordable Care Act provide Forms 1095-C to full time employees. All other providers of Minimum Essential Coverage, provide Forms 1095-B to responsible individuals.

January 31, 2019. All businesses.
Give an annual information statement to recipients of certain payments you made during 2018. (You can use a copy of the appropriate Form 1099.)
File Form 1099-MISC if reporting nonemployee compensation payments in box 7 (otherwise, by Feb. 28, 2019 if on paper, Apr. 1, 2019 if electronically).

February 15, 2019. Individuals.
If you claimed exemption from income tax withholding for 2018 on the Form W-4 you gave your employer, you must file a new Form W-4 by this date to continue your exemption for another year.

February 15, 2019. All businesses.
Give an annual information statement to recipients of certain payments (e.g., proceeds from broker and barter transactions) you made during 2018. (You can use a copy of the appropriate Form 1099.)

February 28, 2019. All businesses.
File an information return (Form 1099) with IRS for certain payments you made during 2018. There are different versions of Form 1099 for different types of payments. For a 30-day extension of time to file, use Form 8809. The due date for electronic filers is Apr. 1, 2019.

February 28, 2019. Large food and beverage establishment employers.
File Form 8027 to report tip income and allocated tips. Use Form 8027-T to summarize and transmit Form 8027 if you have more than one establishment. The duedate for electronic filers is Apr. 1, 2019.

March 1, 2019. Farmers and fishermen.
File your 2018 income tax return (Form 1040) and pay any tax due. However, you have until Apr. 15 (Apr. 17 for taxpayers in Maine and Massachusetts) if you paid your 2018 estimated tax by Jan. 15, 2019.

March 15, 2019. Partnerships.
File a 2018 calendar year return (Form 1065), and provide each partner with a copy of Schedule K-1. If you want an automatic 6-month extension to file the return and provide Schedule K-1 or a substitute Schedule K-1, file Form 7004. Then file Form 1065 by Sept. 16.

March 15, 2019. S corporations.
File a 2018 calendar year income tax return (Form 1120S ), pay any tax still due, and provide each shareholder with a copy of Schedule K-1. If you want an automatic 6-month extension, file Form 7004 and deposit what you estimate you owe.

March 15, 2019. S elections.
File Form 2553 to choose to be treated as an S corporation for calendar year 2019 and thereafter. If Form 2553 is filed late, S treatment will begin with calendar year 2020 (unless the taxpayer qualifies for late election relief).

April 1, 2019. Electronic filers of information returns.
Electronically file those information returns listed under Feb. 28 above (e.g., Form 1099s, Form W-2s, etc.). (Feb. 28 is the due date for non-electronic filers.)

April 15, 2019. Individuals.
Individual taxpayers (except those living in Maine or Massachusetts, who have until Apr. 17) file an income tax return for 2018 (Form 1040), and pay any tax due. Taxpayers who can’t make payments should request (on Form 9465) an agreement to pay in installments. If you want an automatic 6-month extension to file, file Form 4868 or make an electronic payment by Apr. 15. Then file Form 1040 by Oct. 15.
U.S. citizens and resident aliens living and working (or on military duty) outside the U.S. and Puerto Rico are allowed an automatic 2-month extension of time (to June 17) to file their returns and pay any tax due.
If you aren’t paying your 2019 income tax through withholding (or won’t pay in enough tax during the year that way), pay the first installment of your 2019 estimated tax by this date. Use Form 1040-ES, or pay by various electronic means.
Contributions to an IRA for 2018 must be made by Apr. 15.

April 15, 2019. C corporations.
File a 2018 calendar year income tax return (Form 1120), and pay any tax still due. If you want an automatic 6-month extension, file Form 7004 and deposit what you estimate you owe.

April 15, 2019. Corporations.
Calendar year corporations must deposit the first installment of estimated income tax for 2019.