It is taxed as regular earned income, you fill out a form and claim it on your taxes. Billy Baxter who is a pro poker player is famous for his court case to have money won from playing poker classified as earned income. Because at the time it was being taxed at a higher bracket, Baxter's case was that just like a football player or hockey player, poker players make there money the same way, so it should be taxed the same way as other pro sports players. He won the case so it is now earned income and must be reported ti the I.R.S. There are many online sites like z-directory where you can find much details about poker games and also the percentage of taxes applied after winning.