W2-G tax forms copy B, Copy 2, Copy C.  W2-G tax forms are used to report gambling winnings and any income tax withheld on those winnings. The W2-G requirements for reporting depend on the type of gambling, the amount of the gambling winnings, and generally the ratio of the winnings to the wager. Use the W2-G form to print all copies for on winner on a single sheet. Order by the sheet, one sheet per winner. W2-G tax forms are IRS approved.