To amend the Internal Revenue Code of 1986 to require that certain entities exempt from taxation (including business leagues and chambers of commerce) disclose sources and amounts of contributions.

Amends the Internal Revenue Code to require tax-exempt business leagues, chambers of commerce, real estate boards, boards of trade, or professional football leagues to disclose in their annual tax returns the total contributions (including membership dues) received by them during the year and the name and address of, and amount contributed by, each contributor. Exempts organizations whose annual gross receipts do not exceed $25 million.