Section 179 is a tax code section that allows businesses to deduct the total cost of equipment they bought during the year from their taxable income. Enter the total amount of depreciation and the cost of certain property that the business elected to expense under section 179 from Form 4562.Section 179 allows eligible businesses to deduct the full purchase price of qualifying equipment in the year it was put into service. Section 179 is an immediate expense deduction business owners take for purchases of depreciable business equipment instead of capitalizing an asset. Download IRS Tax Form 4797 with instructions. Bystep guide for accurate reporting of business property sales ensuring IRS compliance.