Casino winnings are fully taxable and can bump you into a higher tax bracket. How much you win determines how you're taxed. The casino will take 24% of larger winnings for the IRS before paying you your lump sum.
When you win a large sum of money at a casino, the casino will typically pay you in the form of a check or wire transfer. It's important to note that in many countries, including the United States, you are required to report your gambling winnings as income on your tax return.