There might be donations in box 46 of a T4 or Employee-paid premiums (medical) in box 85 of a T4 which would require an upgrade to allow a claim for additional credits not included in the free version. Please see the list below enumerating what is or is not included in the free version.
Income, credits, and deductions not listed above are not covered by TurboTax Free, including:
Employment expenses (meals, lodging, etc.)
Donations
Medical expenses
Investment income and expenses
Rental property income and expenses
Self-employed income and expenses
Unfortunately, there is no way to downgrade a TurboTax product once it has been upgraded. If you are using TurboTax Online, you’ll need to start a new return to change your product. To start a new return, select “Start a New Return” from under “My Returns” in the top left corner. Once you have started your new return, you can select “View All Returns” from under “My Accounts & Returns”. Then delete the unwanted return by clicking the small Trash Can next to it or “Delete” under the return’s name.
I don't have anything in box 46 or 85 of a T4. I only have a T4A from a co-op and RRSP withdrawals on a T4RSP. No self employed income or rental income. There are medical or other deductions. I have not yet upgraded from the free version but it won't let me file unless I do upgrade