If you're renting the office at fair market value, you must declare the income as rental income, and also you can claim rental expenses.

In this article, you can find the steps to enter your rental income: How do I enter my rental income and expenses in TurboTax? 

Thank you for choosing TurboTax.

Hi

I have a similar question but in different shape.

I am driving for UBER where can I Enter the information and income in Turbo Tax

@Osama2003 If you have your own business, you can enter it as Self-Employment/business income. Use the “Find” tool 🔍 to search for “self”. Select “Self-Employment” and then click the “Go” button.