November 15, 2015

• Open enrollment for tax year 2016 begins at the Health Insurance Marketplace.
• The open enrollment period for tax year 2015 ended on March 15, 2015.

January 4, 2016 (SUBJECT TO CHANGE)

• The Intuit Electronic Filing Center begins accepting and holding ("stockpiling") 2015 tax returns that are final and able to be e-filed.
• The IRS starts processing stockpiled returns on January 18 (subject to change).

January 15, 2016

• Due date for fourth installment of 2015 estimated tax payments.

January TBD

• The IRS starts processing previously stockpiled returns. Most (but not all) are processed on a first-in, first-out basis.
• The IRS will run a small number of stockpiled returns through their systems up to a week before this date for testing purposes.
  • If yours is one of them, please note that your tax refund (if any) will not be processed until after the IRS processing date.

February 15, 2016

• Open enrollment for tax year 2016 ends at the Health Insurance Marketplace.

March 15, 2016

• Deadline for filing a 2015 S corporation or partnership return or extension.

April 18, 2016

• Deadline for filing a 2015 personal, C corporation, or estates/trusts tax returns or extension.
  • The return or extension must be postmarked or transmitted for e-filing by Monday, April 18, 2016.
  • To avoid late payment penalties and interest, any additional taxes you owe must be paid by this date even if you filed an extension. 
• Due date for first installment of 2016 estimated tax payments.

April 25, 2016

• Deadline for resubmitting or paper-filing a rejected federal return that was originally e-filed by the April 18 deadline if you did not file an extension.
  
  • Note: Although the last day to resubmit a rejected return is October 20, the April 25 deadline applies to taxpayers who owe taxes and want to avoid the late-filing penalty.
• Deadline for resubmitting or paper-filing a rejected extension that was originally e-filed by the April 18 deadline.

June 15, 2016

• Deadline for filing a 2015 personal return for U.S. citizens or residents living and working abroad, including military duty.
• Due date for second installment of 2016 estimated tax payments.

September 15, 2016

• Final deadline to file your 2015 S corporation or partnership tax return if you filed an extension.
• Due date for third installment of 2016 estimated tax payments.

September 30, 2016

• Final deadline to file your 2015 estate/trust tax return if you filed an extension.

October 17, 2016

• Final deadline to file your 2015 personal or C corporation tax return if you filed an extension.

October 20, 2016

• Final deadline to resubmit a rejected return that was originally e-filed on or before October 17.
  • If you're expecting a refund and miss the October 20 e-file cutoff date, you have until April 15, 2019 (October 15, 2019 if you filed an extension) to file a paper return and claim your 2015 refund.