A group will be considered a 501(c)(3) if they have sought tax-exempt status as a nonprofit charitable organization under section 501(c)(3) of the Internal Revenue Code. More on that here.
Unlike 501(c)(4)s, 501(c)(3)s can’t engage in any partisan political activity — i.e., activity that supports or opposes specific candidates for public office.
501(c)(3)s can engage in nonpartisan work around elections, including: voter registration, voter education, and issue advocacy, including hosting nonpartisan candidate debates.
Note: because 501(c)(3) status significantly restricts a group’s ability to engage in electoral work, we do not recommend that Indivisible groups seek 501(c)(3) status.