Canada Revenue Agency

General Enquiries 1-800-959-8281 

Have your Social Insurance Number, Address with Postal Code and info from a prior return.

HST/GST  1-800-387-1193

Trillium Benefit 1-877-627-6645

Business Enquiries 1-800-959-5525

Click below for more info:

https://www.canada.ca/en/revenue-agency/corporate/contact-information.html