There are generally two major instances when a vacation qualifies for a business deduction. First is when you are actively searching/interviewing for a new job. Second is when you find yourself traveling for your business. This second reason is why everyone should start a home business.
Looking for new employment.
The IRS
Deductible costs while on the "business trip".
1. Traveling: If you utilize your car while traveling, you may possibly deduct either the costs for travel or simply deduct using the "standard gas mileage rate". The rate is currently set at the rate of $0.50/mile. Transportation will be fully deductible during the entire trip whether using an SUV, plane, bus, or anything else.
2. Food: Meals tend to be deductible at 50% pertaining to both you plus your business associate. If you pay for your colleagues, that as well is 50% deductible in your case.
3. Places to stay: Lodging is fully tax deductible for one's stay. Extra rooms and charges for roll-away beds are not deductible.
4. Entertainment: 50% associated with costs of entertainment are usually tax deductible when you bring a business associate.
5. Miscellaneous: Mobile phone, internet, fax, clothes, tips, and many others things are just about all fully duty deductible.
Further rules:
1. To get tax deductions, expenses must be ordinary and necessary. Luckily in your case the government gives lots of leeway with what is ordinary and necessary. First class travel, high-priced restaurants, and expensive food can all be essential for business. Just remember that there's a difference between a great $250/night accommodation and luxurious $2000/night package. Be reasonable.
2. You should have more days relating to business activities than not.
3. You'll only be able to deduct the expenses directly regarding a spouse, child, or other if he/she is an employee with a legitimate business reason for going on the trip with you.
4. Trips where you leave the continent are more complicated. Investigate the rules thoroughly.