If your job or business requires you to buy a new computer you may be able to deduct the cost as a business expense. It may be possible to deduct the whole amount in a single year.
If you are employed by someone else and are required to purchase a new computer, most time your employer will reimburse you. This is because your employer can deduct the cost of the computer as a business expense. Although if your employer does not reimburse you for the cost of a new computer you may be able to deduct it. The cost will have to exceed 2% of your adjusted gross income, so if you have an AGI of $50,000 your unreimbursed employee expense will have to be greater than $1,000.
If you need to purchase a new computer to use in your business you can fully deduct the cost of the computer. Generally you should depreciate the cost over a five year span, but you are able to deduct the full amount in a single year.
An example of this is; an accountant who works from a home office that is used exclusively for work full time. Since the homes office qualifies for a home office deduction if the if accountant purchases a new computer for $1,000 for his business he can deduct the cost without proof or showing where he uses the computer.