For most Canadians, the online tax software fee is not claimable as expense. However, there are a few scenarios where you can claim the expense:

1. You are self-employed 

You can claim the expense for the online tax software under Professional Fees (including legal and accounting fees on Form T2125, Statement of Business or Professional Activities.

2. You are a commission employee

You can report the accounting software fees as employment expense on Form T777, Statement of Employment Expenses. Note it can only be claimed if your employer submitted a T2200 for you.

3. You earn rental income

You can claim the accounting software fees on Form T776, Statement of Real Estate Rentals.

Here's the link to a relevant TurboTax blog post.