IRS has announced January 24, 2022 as Tax Season start date

The IRS has announced that it will start accepting tax year 2021 US tax returns on January 24, 2022.  US individuals in Canada who report worldwide income typically have to wait for their tax slips such as T3/T4/T5's which are available between February and March. Tax return preparation is more efficient and accurate when all tax documents are provided. 

Taxpayers outside the US have until June 15 to file (2 months after the standard April 15 deadline) but interest accrues on any unpaid balance after April 15.  A filing extension to October 15 is available.  Keep in mind that the IRS continues to handle backlogs from previous year filings.