26 CFR §54.6107-1

1. (a)In general. A person who is a signing tax return preparer of any return or claim for refund of tax under Chapter 43 of subtitle D of the Internal Revenue Code, shall furnish a completed copy of the return or claim for refund to the taxpayer, and retain a completed copy or record in the manner stated in § 1.6107-1 of this chapter.
2. (b)Effective/applicability date. This section is applicable to returns and claims for refund filed after December 31, 2008.