Rates are set by fiscal year, effective October 1 each year. Find current rates in the continental United States ("CONUS Rates").
Travel expenses outside the U.S. are deductible if you can show:
If you're an employee that travels under a reimbursement or allowance arrangement, the IRS assumes you do not have control over the trip arrangements providing:
If someone can override your decision regarding the necessity of the trip, you're not a managing executive.
Self-employed individuals:
A full deduction is allowed for transportation costs if:
If personal activities accounted for 25% or more of your time on a trip lasting more than one week, and you cannot prove that the vacation was a minor consideration in planning the trip you must allocate travel expenses between deductible business and nondeductible personal time spent on the trip.
How to allocate your time:
For purposes of the 25% business test, treat weekends and holidays as time spent on business for business meetings that are scheduled before and after weekends and holidays even if you go sightseeing or enjoy other personal-related activities.
For example, if meetings are scheduled for Friday and Monday, treat Saturday and Sunday as time spent of business for purposes of the 25% business test.
If you extend your business trip through the weekend in order to take advantage of lower air fares, you may deduct the additional expense of meals, lodging, and other incidental expenses.