• You maintain your home office as a condition of employment­, in other words, if your employer specifically requires you to maintain the home office and work there.
• Your home office is necessary for the functioning of your employer's business.
• Or your home office is necessary to allow you to perform your duties as an employee properly.

The convenience of the employer requirement means that you must maintain your home office for your employer's convenience, and not for your own. This requirement isn't satisfied if your use of a home office is merely "appropriate and helpful" in doing your job.

Under the above rules, if your employer requires you to telecommute, and doesn't make on-premises office space available for you, your maintenance of a home office for telecommuting will probably be treated as for the convenience of the employer. Otherwise, it's not clear whether your home office will be treated as satisfying this requirement. Therefore, if you can, you should get your employer to put in writing that it's a requirement of your job to work from an office in your home.

Separate structures. You may deduct the costs of a separate structure used as a home office that is not attached to your "dwelling unit." In other words, the "separate structure" must be an unattached structure on the same property as your home­, for example, an unattached garage, artist's studio, workshop, or office building. To qualify for the deduction, the separate structure must be used exclusively and on a regular basis in connection with your activities as an employee. In addition, you must maintain the home office in the separate structure for the convenience of your employer.

Home office used for meeting patients, clients, or customers. Alternatively, you may deduct your home office expenses if you use a home office, exclusively and on a regular basis, and for the convenience of your employer, to meet or deal with patients, clients, or customers of your employer in the normal course of your duties as an employee.

Principal place of business. In addition, you may deduct your home office expenses if you use your home office, exclusively and on a regular basis, as the principal place of business for your work as an employee, and if you maintain the home office for the convenience of your employer.

While there have been many disputes between IRS and taxpayers about whether taxpayers' home offices qualified as their principal places of business, a telecommuter should have no problem establishing that the home office is his or her principal place of business ­if the telecommuter does the most important part of his or her work in the home office, and spends most of his or her work time there.

Exclusive and regular use requirements. As noted above, whether the home office is in a separate structure or is a principal place of business (which doesn't have to be in a separate structure), the home office must be used exclusively and on a regular basis in connection with your work as an employee.

The exclusive use requirement means that you must use your home office solely for the purpose of carrying on your work as an employee. Any other use of the home office will result in loss of all deductions for your home office expenses.

For example, if you work in a spare bedroom that contains your desk, computer, fax, files, etc., and if you don't use that bedroom for anything but your work, that room passes the exclusive use test. But if you also use the room to sleep occasional overnight guests, it fails the exclusive use requirement. And if you use the room exclusively for work during your regular workday, but the room reverts to other uses at nights and/or on weekends, it also fails the exclusive use test.

The regular basis requirement means that you must use the home office in carrying on your business on a continuous, ongoing or recurring basis. Generally, this means a few hours a week, every week. A few days a month, every month, may do the trick. But occasional, "once-in-a-while" business use won't do.

Dennis & Associates can help you figure out whether your home office satisfies the exclusive and regular use tests, and suggest things you might do to make sure that you do pass these tests. For example, removing non-business furniture and fixtures, not letting guests use your home office, and/or keeping the kids out, etc.

What you get if you qualify for home office deductions. If your home office is your principal place of business under the rules noted above, the costs of traveling between your home office and other work locations in the same trade or business, regardless of whether the other work location is regular or temporary, and regardless of its distance, are deductible transportation expenses, rather than nondeductible commuting costs.

If your use of your home office qualifies under any of the above rules, you may take business expense deductions for the following:

• The "direct expenses" of the home office ­e.g., the costs of painting or repairing the home office, depreciation deductions for furniture and fixtures used in the home office, etc.
• And the "indirect" expenses of maintaining the home office ­e.g., the properly allocable share of utility costs, depreciation, insurance, etc., for your home, as well as an allocable share of mortgage interest, real estate taxes, and casualty losses.