26 CFR §41.6109-2

1. (a)In general. Each excise tax return or claim for refund under section 4481 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.
2. (b)Effective/applicability date. This section is applicable for returns and claims for refund filed after December 31, 2008.