The following article was published by the IRS.
If you gamble, you need to know that gambling winnings are generally taxable and must be reported on your tax return. If you itemize your deductions on Schedule A, then you may also claim your gambling losses and other gambling-activity expenses, such as travel back and forth from a casino or track.
You may only claim these amounts up to the amount of the winnings shown on your tax return, however. It’s a good idea to keep a diary or daily log to show your wins and losses. If you are going to claim your losses and other expenses, then you must keep all related receipts, tickets, and statements.
Examples of gambling income are winnings from lotteries, raffles, horse races, dog races, and casinos. The fair market value of non-cash prizes like cars, houses, and trips is also taxable. Depending on the game and amount of your winnings, the casino, or other payer, may withhold taxes from your payment and give you a Form W2-G. This form shows your winnings and the amount of taxes withheld.
Remember, you need to report all gambling winnings whether or not you receive a W-2G. In many cases, you may also need to make quarterly estimated tax payments. To get more information, go to IRS.gov.