USCIS H-1B Registration Closes at Noon (ET), March 20.

Other Key Dates:

March 1: H-1B registration period opens at noon ET.
March 20: H-1B registration period closes at noon ET.
March 31: Date by which USCIS intends to notify selected registrants.
April 1: The earliest date that FY 2021 H-1B cap-subject petitions may be filed.