https://www.irs.gov/publications/p535

Personal Versus Business Expenses

Generally, you cannot deduct personal, living, or family expenses. However, if you have an expense for something that is used partly for business and partly for personal purposes, divide the total cost between the business and personal parts. You can deduct the business part.

Business use of your home

If you use part of your home for business, you may be able to deduct expenses for the business use of your home. These expenses may include mortgage interest, insurance, utilities, repairs, and depreciation.

To qualify to claim expenses for the business use of your home, you must meet both of the following tests:

1. The business part of your home must be used exclusively and regularly for your trade or business.
2. The business part of your home must be:
   1. Your principal place of business;
   2. A place where you meet or deal with patients, clients, or customers in the normal course of your trade or business; or
   3. A separate structure (not attached to your home) used in connection with your trade or business.

Your home office qualifies as your principal place of business if you meet the following requirements:

• You use the office exclusively and regularly for administrative or management activities of your trade or business.
• You have no other fixed location where you conduct substantial administrative or management activities of your trade or business.

How much can I deduct?

Generally, you can deduct the full amount of a business expense if it meets the criteria of ordinary and necessary and it is not a capital expense.