§ IRS Tax Topics

IRC §162 · 26 U.S.C. §162

IRC §162: Trade or Business Expenses

By Paul D. Diaz, EA, MBA · Updated

IRC §162 allows a deduction for all ordinary and necessary expenses paid or incurred in carrying on a trade or business. Ordinary means common in your field; necessary means helpful, not indispensable. Personal expenses are never deductible here — the business/personal line is where examinations live.

What it governs

In the GuideFull treatment in Chapter 3 of the Guide — THE TAX CUTTERY® Guide to Federal Income Taxation, Professional Edition (564 pages, 24 chapters).
From the practiceDeductions under examination →

Questions this section answers

Can I deduct startup costs under §162?
Not immediately — pre-opening costs fall under §195 amortization once the business begins. §162 covers carrying on, not starting up.
What makes an expense 'necessary'?
Helpful and appropriate for the business — the Supreme Court set the bar at helpful, not essential. Ordinary, common in the field, does the heavier lifting.
Why do meals and travel get extra scrutiny?
Because §162 allows them but §274 demands strict substantiation — the deduction exists, then the records rule bites.
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