Travel expenses must be ordinary and necessary. They can't be lavish, extravagant or for personal purposes. Employers can deduct travel expenses paid or incurred during a temporary work assignment if the assignment length does not exceed one year.

The "business trip rule" refers to the set of corporate policies and tax regulations—primarily defined by the IRS in the U.S.—that dictate which travel expenses are tax-deductible or reimbursable. To qualify as a legitimate business trip in 2026, the travel must be "ordinary and necessary" for your profession and take you away from your "tax home" for longer than a standard workday, requiring sleep or rest. A key component is the "Primary Purpose" rule: if the trip is entirely for business, 100% of the transportation is deductible; if it is a "bleisure" trip (business + leisure), you can only deduct the business-related portions like lodging for those specific days. Meals are typically subject to a 50% deduction limit, and many companies follow the GSA's "Per Diem" rates to determine daily spending allowances for employees. Documentation is critical, as the IRS requires a record of the time, place, and business purpose of every expense to prevent "personal" travel from being disguised as a company cost.