For business travelers and self-employed individuals, travel expenses are tax-deductible if they are "ordinary and necessary" for the conduct of your trade or business. This primarily includes the cost of transportation, such as airfare, train tickets, or car rentals, and the use of your personal vehicle (calculated via the standard mileage rate or actual expenses). Lodging is also deductible as long as the trip requires an overnight stay away from your "tax home." For meals, the IRS usually allows a 50% deduction of the actual cost or a standard daily allowance (per diem). Other miscellaneous deductible expenses include baggage fees, dry cleaning during the trip, business calls, and tips paid for any of these services. Crucially, if a trip is split between business and personal time, you can only deduct the portions directly related to business. For example, if you fly to a conference for three days and stay for an extra two days for vacation, only the flight and the three days of business-related lodging/meals are deductible. Proper documentation, like receipts and a log of business activities, is absolutely essential to survive an audit.