Travel away from home
A travel expense is deductible only if your business reasonably requires you to be away from your tax home substantially longer than an ordinary day's work, AND you need sleep or rest while away. Tax home is generally the city of your principal place of business — not necessarily where you live.
What qualifies
Deductible travel expenses include transportation (airfare, rental car), lodging, 50% of meals (per diem or actual), incidentals, business calls, baggage and shipping, and tips. Personal side-trips are not deductible — if a 5-day trip includes 1 vacation day, allocate the lodging and meals accordingly.
Vehicle expenses
You may deduct car expenses using the standard mileage rate (set annually; e.g., 67¢ per mile for 2024) or actual expenses (gas, oil, insurance, repairs, depreciation, lease payments) prorated by business-use percentage. Standard mileage requires that you choose the method in the first year a vehicle is placed in service, with limited switching rights afterward.
Recordkeeping requirements
Section 274(d) requires contemporaneous records for travel, vehicle, and entertainment expenses: amount, time, place, and business purpose. A weekly summary written in retrospect is generally sufficient, but reconstructed-from-memory records years later are often disallowed in audit.
Business gifts
Business gifts are deductible up to $25 per recipient per year. Branded promotional items costing $4 or less, or items clearly intended for business use (a business calendar, a notepad), are not subject to the $25 limit.
What the publication does not say
IRS publications are summaries, not the law. They do not cite every controlling regulation, and they routinely omit edge cases that would make the discussion harder to read. For close calls, escalate from the publication to the underlying Internal Revenue Code section, the related Treasury regulations, the relevant revenue rulings or revenue procedures, and (if the dollars warrant) the leading court cases. The IRS-published Internal Revenue Manual and the Audit Techniques Guides — also free on IRS.gov — provide the agency's internal procedural perspective, which often clarifies how the publication's rules play out in an examination.