When ever I hit over $1100.00 at a land based casino, that was when they wanted my SS # and they gave me the tax form. When you win over that amount and you have to claim it on your taxes, you can take all of your losses off that you have had for that year,
not just for the day you won the jackpot. It does not have to be just casino losses. It can be any gambling loss. You can claim losses up to the amount of your winnings but not over the amount that you have won.