If I have all my income reported on a T4A slip, what do a I put in the professional fees box? Just my GST?

[TrentS]

Hi @loanedwolf - Trent here from TurboTax to help!

If the income reported on your T4A slip is related to a Self-Employment income you will have to complete a T2125 Form (Self-Employment Income) and there you can enter all the expenses and other information that are required to complete your return. 

Here are some links that might help:
https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/sole-proprietorships-partners... 
https://www.canada.ca/en/revenue-agency/services/forms-publications/forms/t2125.html