A 501(c)(3) organization is a tax exempt organization and is typically a religious, educational, charitable or literary organization. Companies that qualify as 501(c)(3) can provide Ad-ID with their IRS determination letter confirming their 501(c)(3) status and receive free codes.
There are other non-profit companies that fall under different IRS codes which do not qualify for the 501(c)(3) Program. All companies which are not 501(c)(3) organizations are subject to the standard Ad-ID rates.