March 15 – 2012 Calendar-year corporation income tax returns are due. Extensions may be filed to give until September 17, 2012, to file.
March 15 – Deadline for calendar-year corporations to elect S corporation status for 2012.
April 2 – Deadline for payers who file electronically to send copies of 2011 W-2s to the Social Security Administration.
April 2 – Deadline for payers who file electronically to file 2011 information returns (such as 1099s) with the IRS.