Form 8879-C, IRS e-file Signature Authorization for Form 1120, is now historical. The 2021 revision is the last revision of the form. Prior revisions will be available on IRS.gov. Beginning with the 2022 tax year, previous users of Form 8879-C will use new Form 8879-CORP, E-file Authorization for Corporations. Form 8879-CORP will be used for e-file authorizations for Form 1120, Form 1120-F, and Form 1120-S.