Can I deduct my wife and my airfare to Japan to do a lecture at a school in Tokyo?

[Vanessa · Accepted solution]

If this meets the qualification of entirely business travel then yes you would be able to deduct YOUR airfare.  Unless your wife was also on a business trip, then her airfare would not be deductible. 

If your travel was not ENTIRELY for business, you would need to allocate the fee based on business vs nonbusiness days. You would not be able to deduct the non-business portion. 

"You determine the nonbusiness portion of that expense by multiplying it by a fraction. The numerator (top number) of the fraction is the number of nonbusiness days during your travel outside the United States and the denominator (bottom number) is the total number of days you spend outside the United States." https://www.irs.gov/publications/p463#en_US_2017_publink100033819