A corporation formed for a nonprofit purpose, such as charitable, educational, political, social, or trade organizations. Usually called a 501(c)(3) corporation after Section 501(c)(3) of the Internal Revenue Code.All such corporations with tax-exempt status are required to file annual reports with the IRS on Form 990.You may view the tax deductibility of contributions and past 990 forms for particular organizations free of charge at the Web site for Philanthropic Research, Inc., www.guidestar.org. See also eleemosynary corporation.