December 15:
4th Quarter 2015 estimated tax payments are due for calendar-year corporations
November payroll and nonpayroll withholding taxes are due
January 15:
4th Quarter 2015 estimated tax payments are due for individuals and calendar-year estates and trusts
December payroll and nonpayroll withholding taxes are due
February 1:
W-2s and 1099s are due to employees and other payees
Employer Form 941 (for 4th Quarter) and Form 944 (for 2015) are due
Employer Form 940 is due for 2015
Form 945 to report income withheld for 2015 on all nonpayroll items.
*If the appropriate taxes are paid in full, deposited on time, and filed properly, Forms 940, 941,943, 944, and 945 are not due until February 10th.