Here is a a helpful resource related to deductions for business travel. As it pertains to your client flying you out for international travel, you will unlikely be able to deduct expenses that your client paid for, but costs associated with that travel that are not covered may be deductible. The important thing regarding travel deductions is that the expenses must be ordinary (common and accepted in your industry) and/or necessary (helpful and appropriate for your business) and for the purpose of doing business.