You will post the commission fees in the Business Expenses section.  

The expenses will be entered in the Business and Expenses section. Please follow the instructions below to get to the section needed to enter expenses.

       1. Log into your TurboTax online account and click on the Business tab and select Continue

       2.  Select “I’ll choose what I work on” and this takes you to “Let’s gather your business info” screen

       3. The first section down is Business Income and Expenses, choose Update

       4.  You are now at the “Here’s  the business info we have so far” screen where you should see your Business listed

       5. Click Edit next to that business and on the next screen, scroll down to the fourth section which should be Business Expenses and select “Visit All”

This is where you will be able to enter all expenses associated with your business.