26 CFR 54.6109-1: -1 Tax return preparers furnishing identifying numbers for returns or claims for refund filed.

(a) In general. Each tax return or claim for refund of tax under Chapter 43 of subtitle D prepared by one or more signing tax return preparers must include the identifying number of the preparer required by § 1.6695-1(b) of this chapter to sign the return or claim for refund in the manner stated in § 1.6109-2 of this chapter.

(b) Effective/applicability date. Paragraph (a) of this section is applicable to returns and claims for refund filed after December 31, 2008.