If you have never gambled of any kind, you may not know that all income from gambling is fully taxable. The Internal Revenue Service (IRS) works hard to ensure that all winners of casino games and sports betting markets pay their fair share of tax. Individuals that file annual tax returns must make note of their winnings. Those who win a “substantial” payout will be taxed 24% at source. The online casino will provide a copy of the IRS Form W-G2 to formalize the transaction. A “substantial” sum equates to $1,200 on a slot or bingo game, $1,500 in a keno game, and $5,000 in lotteries and wagering pools.