About 52 percent of all businesses are run from home. The number of teleworkers is growing annually.

It's good to know that some tax savings can result from this work arrangement.

A portion of personal expenses for your home can be turned into a business deduction -- if you meet certain rules.

To claim a home-office deduction, you must use the space in your residence as a principal place of business, as a place to meet or deal with customers on a regular basis, or as a separate structure used for the business.

You also must do the above regularly and exclusively for business.

If you're an employee, you must use the space for your employer's convenience and not for your own preference. Working after hours at home rather than staying late at the office is probably your own choice and not for your employer's convenience.

Usually, "employer's convenience" means that the employer does not have space for you on the company's premises.

But while the home-office deduction rules are written in black and white, there are some uncertainties that could affect your home office deduction. Think of them as gray areas.

One is the meaning of exclusive use. Clearly, the space must be available 24/7 for business and cannot be used by you or your family for personal reasons at any time during the day or night. Thus, if you use a TV room as an office during the day and your family watches TV there in the evening, you fail the exclusive-use test.

But what about walking through a room? The Tax Court has said that even occasional use of space, such as using a bathroom by family or guests, means your business use is not exclusive. However, the court has also said that incidental use of space, such as family members walking through the office to get to another part of the home, is minimal and won't cause you to fail the exclusive use test.

What's the difference between occasional and incidental use?

This is a gray area, but it seems that passing through is not equivalent to using the space.

Storage of some personal items in a space claimed as a home office won't violate the exclusive-use test. The court has allowed a home office deduction for a garage in which some personal items were kept. So, people, no. Things, yes.

A common belief is that claiming a home office deduction is a red flag to the IRS, practically inviting an audit. There is no IRS data to support this belief and, unfortunately, the belief may be responsible for some taxpayers forgoing the deduction needlessly even though they are otherwise eligible for it.

The best course of action is to talk over your personal situation with a tax advisor to make sure you meet the home office deduction rules.

Keep good records of all expenses related to the home office, and take a photo of the space used as a home office. The photo can help in case the IRS questions your return after you've stopped using the space for business.

To learn more about the home-office deduction rules, see IRS Publication 587, Business Use of Your Home.

This article was written by Barbara Weltman and published in The Wall Street Journal.