Form 990 series returns are required to be filed by most tax-exempt organizations, except for church and government-affiliated organizations. Form 990 is the IRS primary tool for gathering information about tax-exempt organizations, for educating organizations about tax law requirements and ensuring their compliance. Organizations use it to inform the public about their programs. In addition, most states rely on Form 990 to perform charitable and other regulatory oversight, and to satisfy state income tax filing requirements for organizations claiming exemption from state income tax. More Information.