You are required to pay taxes on any and all income you make, regardless of the source.

For the casual gambler, the amount of money you can earn without needing to report is $600 per year (if memory serves me). If you make more than this amount, then you are required to pay taxes. You should be able to declare your winnings as ‘Other Income’ on your tax return and pay your taxes accordingly.

If you’re not a casual gambler, then it’s a bit more difficult, as you need to keep track of all of your gambling sessions. A detailed gambling log book of your daily wins or losses is required by the IRS for gambling incoming, so that you and they can accurately tally your overall profit to be taxed. You should be doing this anyways if you’re a serious player, so it’s good advice to follow.