The Secretary shall include with each notice to an individual taxpayer which includes an amount of interest required to be paid by such taxpayer under this title information with respect to the section of this title under which the interest is imposed and a computation of the interest.
26 U.S. Code § 6631. Notice requirements
“The amendments made by this section [enacting this subchapter] shall apply to notices issued after June 30, 2001. In the case of any notice issued after June 30, 2001, and before July 1, 2003, to which section 6631 of the Internal Revenue Code of 1986 applies, the requirements of section 6631 of such Code shall be treated as met if such notice contains a telephone number at which the taxpayer can request a copy of the taxpayer’s payment history relating to interest amounts included in such notice.”