On April 20, 2006 CRS released Tax-Exempt Organizations: Political Activity Restrictions and Disclosure Requirements, which explains the Internal Revenue Code (IRC) limitations on lobbying and campaign intervention by groups exempt under IRC 501(c)(3) (charities, religious organizations and private foundations), 501(c)(4) (social welfare organizations), 501(c)(5) (labor unions), 501(c)(6) (trade associations) and 527 political committees.
501(c)(3) Organizations