Publication 417, Nonprofit USPS Marketing Mail Eligibility: Nonprofit and Other Qualified Organizations > 3 Application for Authorization > 3-3 Mailing After Authorization
The organization must make at least one mailing at the Nonprofit USPS Marketing Mail prices during a 2-year period or the authorization to mail at the nonprofit prices will be automatically revoked for nonuse. A primary authorization (the authorization obtained by filing PS Form 3624) will not be revoked for nonuse if one or more nonprofit mailings have been made during the 2-year period at the primary authorization Post Office or at an additional mailing office where authorization is based upon the primary authorization. An additional mailing office authorization, if no mailings at the Nonprofit USPS Marketing Mail prices have been made under that authorization during a 2-year period, will be revoked for nonuse. The PCSC notifies the organization of the revocation for nonuse whether the entry is a primary or an additional office authorization.