If you use your home computer for business purposes, knowing that you can deduct some or all of its costs can help ease the pain of the large initial and ongoing cash outlays. However, there are some tricky IRS rules that you should consider before taking - or forgoing - a deduction for home computer costs.

Although the cost of computers and peripheral equipment has dropped significantly over the past year, a tax deduction for all or part of the expense can still help lower the bottom-line price tag of this major purchase. But despite both the widespread use of computers and the temptation to somehow "write them off" on a tax return, the IRS has remained surprisingly quiet. Rather than release any direct guidance on the issue, the IRS has chosen to rely on old rules that were established before the recent computer revolution. As a result, the business use of your home computer will need to fall within these standard rules if you want to take any related deductions.

In order to claim a deduction for your home computer and any peripheral equipment, you will need to prove that the expense occurred in connection with an active business - just as you would for any other business expense. An active business for purposes of a business expense related to a home computer will usually arise from one of two types of business activities: as a self-employed sole proprietor of an independently-run profit-making business; or as an employee doing work from home. Deductions from both types of activities are handled differently on an individual's income tax return and there are separate conditions that must be met for either scenario.

Self-employed person. In order for you as a self-employed person to deduct computer-related costs on Schedule C - whether for a home-based computer or one in a separate business location - it is required that your expenses relate to a profit-motivated business versus a "hobby". In the eyes of the IRS, a business will be deemed a hobby if there is no profit motive and the "business" is half-heartedly pursued simply to write off items or achieve some other personal purpose. If your Schedule C business shows a net loss year after year, you may be considerably more likely to have the IRS audit your return to inspect whether your purported business is actually legitimate under the tax law.

Employee. A miscellaneous itemized deduction on Schedule A is allowed for computer costs that are directly related to the "job" of being an employee. In order to claim a deduction for computer-related expenses as an employee, you must show a legitimate reason related to your employment for regularly using a computer at home. The availability of a computer in the office, the ability for you to keep your job without the home computer, the lack of telecommuting policy at work, or the lack of proof that your computer is used regularly for office work will make it more difficult to convince the IRS that a legitimate business reason exists for the deduction.

Some taxpayers have succeeded in writing off the expense of a computer as an educational expense related to business. For you to succeed in this deduction, you must carefully document that the education is undertaken to maintain or improve skills required in your current business or employment, or to meet specific educational requirements set by your employer. Computer expenses related to education that qualifies you for a new trade or business is not deductible.

Note to employees: computer-related business expenses taken as a miscellaneous itemized deduction are deductible only to the extent that your total miscellaneous itemized deductions exceed 2 percent of your adjusted gross income. For many taxpayers, a good strategy is to "bunch" purchases of computer equipment all in one year so that more of the cost will rise above the 2 percent floor.

Aside from applying the general rules discussed above for a for-profit business and miscellaneous itemized deductions to determine if you are able to deduct business-related computer costs, the IRS is likely to dust off other standard tax principles in evaluating whether your computer expense write off is acceptable: