Where to input flea market booth income/expenses?

You should report the income from the flea market booth on Schedule C. For tax purposes, you are self-employed. You are also able to deduct expenses from this work, such as supplies.

Here's how to report your flea market business in TurboTax Online:

• Navigate to Federal > Wages & Income > Self-employment income and expenses > Start
• Answer "Yes" to the question "Did you have any self-employment income or expenses?"
• Give a description of the business, such as "Flea Market Sales" or a description of your choice
• Continue until the interview asks "how does your work fit into your big picture?", based on the information you provided, it's a side job and/or a business.
• Answer all the informational questions until you get to the screen  "Let's enter the income for your work."  Here, enter that you received common income- Other self-employed income, including cash and checks; then enter what your were paid.
• Once you've entered your income, type in your expenses in the proper categories, TurboTax Online will recommend popular categories, but refer to your records to ensure you are deducting all of your expenses

If the income is part of what you would consider a re-sale business, you would put the income down as part of the business taxes (which would include deductions for expenses like booth rental fees, etc.) If it's not a business and you consider it a hobby, it could be hobby income. It also depends on how much the income is and whether there are records of it. If it's a small amount and there is no paper trail, you may choose not to report it all. Most people probably wouldn't.