There has recently been significant expansion of the federal laws and regulations requiring tax-exempt organizations to provide public access to documents they submit to the IRS, including annual tax returns (Form 990 and its relatives) ......[snip]
In short, almost all tax-exempt organizations are now required to provide public access in a timely fashion to their most recent three years of federal tax returns and to their original Application for Recognition of Exemption. These must be complete, including From 990 Schedule A and all other accompanying materials submitted to the IRS, with the sole exception of those attachments that name individual donors. There are significant fines for noncompliance.
Generally speaking, people who visit one of the tax-exempt organization's offices and ask for these materials must be provided with the opportunity to view and copy them, and tax-exempt organizations must send copies of these materials by mail upon request. Minor fees for copying, postage and other processing may be assessed. An exception to these required access mechanisms is made if the organization makes the materials 'widely available,' which may be satisfied by publishing them on the Internet in a suitable format.
Nonprofit.org index (dead link)
This quote source (dead link)