The consequences of taking special depreciation (or any depreciation) is that you may have a taxable event when you sell the computer or stop using it for your business.
A computer is an asset, which much generally be depreciated over it's useful life, as defined in accounting manuals. I think a computer is 5 years, although I haven't double-checked. When you place the asset in service, you begin to depreciate it using the cost (if bought new) or the fair market value at the time it was placed in service (as a used computer). Using simple depreciation, you would deduct 1/5 the cost over 5 years (more or less). With special depreciation, you can deduct the entire cost up front.
There are two consequences here. First, if you stop using the computer in business before the end of the class depreciation period, you have to repay (recapture) the unused part of the depreciation. (This rule only applies to section 179 depreciation.)
Second (and this rule applies to all depreciation), if you sell the computer later, even as used, that may be taxable business income. If you take regular depreciation over 5 years or special depreciation, you deduct the cost of the asset as a business expense. That means that it's cost basis—the amount of after-tax dollars you have invested in the asset—is reduced to zero. If you sell it for more than the cost basis, the difference is a taxable capital gain. (This may not apply to you if you only depreciate a percentage of business use. If you paid $3000 and you claim 2/3 business use, then your cost basis after depreciation is $1000, and you would only have a taxable event if you sold it for more than $1000. If you sold it for less than $1000, you may even be able to deduct 2/3 of the "loss" as an additional business expense.)
Once you list the asset in Turbotax, the program will track it, and if and when you dispose of it, you must report that in Turbotax and the program will tell you the consequences.
If you don't use the computer 100% for your business, then you can only depreciate the percentage of business use. If you are unlucky enough to be audited, the IRS will want to see some kind of reliable written record showing how you determined the business use percentage. You might have a data log or a time log or an app you use to keep track of the hours you use it for business and personal use, but you must have some type of reliable record, otherwise, the IRS does not have to allow it as a business expense.
