Genealogical societies, historical societies, preservation groups, museums, friends of the library groups and similar 501 (c)(3) organizations that previously did not have to file annual reports with the IRS are now required to do so. The IRS had granted an extension until Oct. 1. Any tax-exempt organizations that has not filed for three consecutive years will lose their tax-exempt status.
For instance, in the Commonwealth of Massachusetts alone, more than 7,900 non-profit organizations are at risk of losing their tax status. The list includes all sorts of non-profit organizations, not just genealogical and historical societies.
The list of at-risk organizations can be found at http://www.irs.gov/charities/article/0,,id=225889,00.html