The business part of your home must be exclusively and regularly used for your business. The business part of your home must be your principal place of business; a place where you meet or deal with patients, clients, or customers in the normal course of your business; or a separate structure (not attached to your home) that you use in connection with your business.

To qualify under the exclusive use test, you must use a specific area of your home only for your trade or business. The area used for business can be a room or other separately identifiable space. The space does not need to be marked off by a permanent partition. You do not meet the requirements of the exclusive use test if you use the area in your home both for business and for personal purposes. There are separate IRS rules if you use part of your home for the storage of inventory or product samples or as a daycare facility.

To qualify under the regular use test, you must use a specific area of your home business on a continuing basis, not an occasional or incidental use, even if you do not use that area for any other purpose.

See IRS Publication 587.