Capitalizing vs expensing
Property with a useful life of more than one year that is used in your trade or business must generally be capitalized and depreciated over its recovery period rather than expensed in the year of purchase. The de minimis safe harbor election lets you expense items costing $2,500 or less ($5,000 with audited financials) per invoice or item.
Section 179 immediate expense
Section 179 lets active small businesses deduct the full cost of qualifying tangible personal property in the year placed in service, up to an annual cap (over $1 million, indexed). Real property generally does not qualify (with limited exceptions for qualified improvement property, roofs, HVAC, security and fire systems on commercial property).
Bonus depreciation
Bonus depreciation is a separate election that lets you depreciate a percentage of new and used qualifying property in the first year. Through 2022 the percentage was 100%; it is phasing down 20 percentage points per year. Bonus depreciation can be elected out class-by-class, which is useful when state conformity is incomplete.
Listed property
Vehicles weighing 6,000 lbs or less, computers used outside the office (in earlier years), and entertainment property face stricter substantiation rules. Failing the >50% business-use test triggers straight-line depreciation, no Section 179, and a recapture computation if business use later drops.
Catch-up depreciation
Forgot to depreciate an asset in prior years? File Form 3115 to claim a Section 481(a) catch-up adjustment. The cumulative missed depreciation is deductible in the year of change, often producing a significant one-time loss.
How to find what you need quickly
Reading an IRS publication straight through is rarely the right move; using it as a reference is. Open the PDF, jump to the table of contents, identify the chapter that matches your facts, and skim the worked examples at the end of that chapter first — they usually answer 80% of practical questions. The detailed rules in the body of the chapter then make sense in the context of an example. The publication's index, while less polished than a commercial tax-research database, is searchable in any PDF reader with Ctrl+F and surfaces the exact paragraph you need in seconds.