You must fill out Form 5754 [Statement by Person(s) Receiving Gambling Winnings] before you can receive a Form W-2G [Certain Gambling Winnings] if you are accepting gambling winnings for another person, or you are receiving the winnings as part of a group, such as a number of people who shared the same winning lottery ticket.
Part I of the form lists the name of the person to whom the gambling winnings are paid. Part II of the form lists all of the people to whom the winnings are taxable, in other words, all of the people who are going to receive a share of the winnings. The IRS wants to make sure that if the winnings are split, one person doesn’t end up paying the whole tax.
The information submitted on Form 5754 will help the payer of the winnings fill out a separate W-2G for each of the people who will receive money, apportioning the tax between them.