In the Home Office section of TurboTax, you can add the square footage of the structure to your home total.
You can deduct expenses for a separate free-standing structure, such as a studio, workshop, garage, or barn, if you use it exclusively and regularly for your business. The structure does not have to be your principal place of business or a place where you meet patients, clients, or customers.
Example. E operates a floral shop in town. E grows the plants for their shop in a greenhouse located at home. E uses the greenhouse exclusively and regularly for their business, so that E can deduct the expenses for its use (subject to certain limitations, described later).