26 CFR §20.6696-1

1. (a)In general. For rules for claims for credit or refund by a tax return preparer who prepared a return or claim for refund for estate tax under chapter 11 of subtitle B of the Internal Revenue Code, or by an appraiser that prepared an appraisal in connection with such a return or claim for refund under section 6695A, the rules under § 1.6696-1 of this chapter will apply.
2. (b)Effective/applicability date. This section is applicable to returns and claims for refund filed, and advice provided, after December 31, 2008.