Form of federal informational tax return filed annually by publicly supported charities, unless they qualify for an exception to the filing requirement. Nearly all of Form 990 is public information under federal law. See Public inspection copy of Form 990. Private foundations like the King Foundation file a similar tax return called the Form 990-PF. Any charity, whether public or private, that has certain kinds of income must also file a Form 990-T. Both the 990-PF and the 990-T are subject to public inspection.