March 1, 2018 @ 12:00 am - March 2, 2018 @ 12:00 am Farmers and fishermen: File Form 1040 and pay any tax due. However, you have until Apr 17 to file if you paid your 2017 estimated tax payments by Jan 16, 2018.
February 28, 2018 @ 12:00 am - March 1, 2018 @ 12:00 am File a new Form W-4 if you claimed exemption from income tax withholding in 2017 (see Publication 15 for details).
February 28, 2018 @ 12:00 am - March 1, 2018 @ 12:00 am Begin withholding on employees who claimed exemption from withholding in 2017 but did not file a W-4 to continue withholding exemption in 2018 (see Pub 15 for details).