Section 179 deduction dollar limits. Section 179 allows eligible businesses to deduct the full purchase price of qualifying equipment in the year it was put into service.A Section 179 expense is a business asset that can be written off for tax purposes right away rather than being depreciated over time. This publication explains how you can recover the cost of business or income-producing property through deductions for depreciation. It includes all costs associated with putting an asset into use (such as sales tax, delivery and freight charges, installation, labor, etc.). Under Section 179, you can claim a deduction in the current year.