If you won it in 2017 you will report it on 2018's taxes.
Money you won while gambling is usually reported on Form W2-G, Certain Gambling Winnings. Gambling losses can be deducted if you itemize, but only up to the amount you reported winning.
For example, if you fed your local casino's slot machines $200 last
year and won $50 of it back, you'd report $50 in winnings. You could
then deduct $50 in losses (essentially wiping out $50 of taxable income)
but only if you itemize.
On the other hand, if you don't itemize, or if the casino kept the entire $200, you cannot deduct anything.
After you enter all your W-2Gs in TurboTax, we'll ask you to enter your gambling losses.