Do I need a T1139 form?

As per CRA: Use this form if you are a self-employed business person, including a self-employed commission salesperson, a professional, a farmer, or a fisher, and you:

- started your business in 2019 or 2020 and are electing to use the alternative method to have a fiscal period that does not end on December 31, effective for the first fiscal period of your business

- already elected to have a fiscal period that does not end on December 31 and is calculating your additional business income. This is mandatory if you have made this election. Fill in all the information in Part 2 that applies - are cancelling your previous election and are now going to use a fiscal period that ends on December 31; fill in all the information in Part 5 that applies

- are calculating your business or professional income to report on your 2020 income tax and benefit return