All gambling winnings — from casinos, lotteries, sports betting, or online games — are fully taxable as ordinary income. Casinos and other payers will issue a Form W-2G if you win above certain thresholds. You can deduct gambling losses, but only up to the amount of your winnings, and only if you itemize deductions. Keep a log of your wins and losses throughout the year. Failing to report gambling income is a common IRS audit trigger.