Tax Law and Guidance Nonprofit Organizations   Form 990 series (990, 990EZ, and 990PF) for IRS and District of Columbia recognized tax exempt organizations are available online through Philanthropic Research, Inc., also known as GuideStar, a 501(c)(3) nonprofit organization. GuideStar maintains information on their website about tax exempt organizations. GuideStar+ + This link is provided by the CFO office as a courtesy. The District government is not responsible for information on websites outside the DC portal. Inquiries should be made to the sponsoring organization.