December 31, 2011
Deduction Deadline. The last day to make payments which can be deducted from your 2010 tax return.
January 14, 2012
First day that the IRS will accept electronically filed tax returns. However, many taxpayers will need to wait to file their returns (whether e-file or by mail) due to last-minute legislative changes.
January 17, 2012
Deadline to pay your fourth quarter estimated tax payment.
January 31, 2012
Deadline for employers to mail out Form W-2 and for businesses to furnish Form 1099 statements reporting, among other things, non-employee compensation, bank interest, dividends, and distributions from a retirement plan.
Deadline for self-employed individuals to file and to pay their tax and avoid an penalty for not making your 4th quarter estimated tax payment.
February 15, 2012
Deadline for employees who claim exemption from withholding to file a new Form W-4 with their employers.
February 28, 2012
Deadline for all businesses to file information returns (form 1099) for certain payments you made during 2011
March 1, 2012
Deadline for farmers and fishermen to file your 2011 income tax return (Form 1040) and pay any tax due due. However, youhave until April 17to file if youpaidyour2011estimatedtaxby January 17, 2012
March 15, 2012
Deadline for corporate tax returns (Forms 1120 and 1120S), or to request automatic 6-month extension of time to file (Form 7004).
April 17, 2012
Deadline to file individual tax returns (Form 1040, 1040A, or 1040EZ) and pay any tax due. If you want an automatic 6 month extension of time to file the return, file (Form 4868).
1st quarter estimated tax payments due for the 2012 tax year.
June 15, 2012
2nd quarter estimated tax payments due for 2012 tax year.
September 17, 2012
3rd quarter estimated tax payments due for 2012 tax year.
Final deadline to file corporate tax returns if an extension was requested. (Forms 1120, 1120A, 1120S).
October 3, 2012
Final deadline for self-employed persons or employers to establish a SIMPLE IRA for the year 2011.
October 15, 2012
Final deadline to file individual tax returns (with extension).
December 31, 2012
Deduction deadline. The last date to make payments that can be deducted from your 2011 return.
Marital status on this date determines your marital status for the whole year.
Source: http://www.irs.gov/publications/p509/index.html
Updated Jan. 4, 2012