From the Internal Revenue Service website:
The new regulations do away with the so-called advance rulings that granted public charity status for an initial five-year period but required exempt organizations to demonstrate, after the initial period, that they in fact received a substantial part of their support from public sources to receive a final determination letter. Private foundations under federal law are subject to more restrictions on the way they operate than publicly supported charities. To apply for exempt status either as a private foundation or as a publicly supported charity, an organization must file a Form 1023, the application for recognition of tax exemption.
