The Internal Revenue Service maintains Exempt Organizations Select Check, an online tool that you can use to search for exempt organizations and check information about their federal tax status and filings. You can search for:

• Organizations eligible to receive tax-deductible charitable contributions (Publication 78 data),
• Organizations whose federal tax exemption was automatically revoked for not filing a Form 990-series return or notice for three consecutive years, or
• Form 990-N (e-Postcard) filers and filings.

Go to the IRS Exempt Organizations Select Check page