You can deduct any travel expenses if they are ordinary and necessary expenses that you incur traveling away from home in connection with the pursuit of an existing business.
You can't deduct travel expenses to the extent that they are lavish or extravagant - the expenses must be reasonable considering the facts and circumstances. However, the IRS gives you a great deal of latitude here. Your expenses won't be denied simply because you decided to fly first class, or dine in four-star restaurants
Deductible travel expenses while away from home include, but are not limited to, the costs of:
Instead of keeping records of your meal expenses and deducting the actual cost, you can generally use a standard meal allowance, which varies depending on where you travel. The deduction for business meals is generally limited to 50% of the unreimbursed cost.
For more information see http://www.irs.gov/taxtopics/tc511.html and http://taxguide.completetax.com/text/Q13_2630.asp
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