GST/HST electronic filing is available seven days a week during the following hours:

• Pacific time zone
  3:00 am to 11:30 pm
  
• Mountain time zone
  4:00 am to 12:30 am
  
• Central time zone
  5:00 am to 1:30 am
  
• Eastern time zone
  6:00 am to 2:30 am
  
• Atlantic time zone
  7:00 am to 3:30 am
  
• Newfoundland time zone
  7:30 am to 4:00 am