You will depreciate your office condo as a business non-residential real property (Office Building) asset over 39 years.
Select the "Business" tab, then press "Continue"
On the "How do you want to enter your business income?" screen press "I'll choose what I work on"
On the "Let's gather your business info" screen select "Schedule C, Form 1099-MISC" under the "Business Income and Expenses" heading, then press "Start" or "Update"
Since you have already entered information for your business, click "Edit" on the "Here's the business info we have so far" screen
On the "Your Business" screen, scroll down to "Business Assets" and press "Update"
On the "Any Large Purchases (Depreciable Assets)?" screen, press "Yes"
(See one of the two attached screenshots below. Click to enlarge.)
