; or (B) a Series I United States savings bond. (3) Bonds to be credited to single account Each retirement savings bond issued to the designated Roth IRA custodian shall be credited to a single Roth IRA established through the MyRA Program on behalf of a participant. (4) Reissue in case of change in custodian If a successor designated Roth IRA custodian is designated under subsection (b)(4), the retirement savings bonds issued to the predecessor designated Roth IRA custodian shall be reissued to such successor. (d) Roth IRA For purposes of this section, the term Roth IRA has the meaning given such term by section 408A(b) of the Internal Revenue Code of 1986. 4. Promotion and guidance (a) Promotion The Secretary of the Treasury (or the Secretary's delegate) shall educate taxpayers on the benefits provided under section 6433 of the Internal Revenue Code of 1986 and the myRA Program established under section 3 of this Act. (b) Guidance Not later than December 31, 2020, the Secretary of the Treasury (or the Secretary's delegate) shall issue guidance on the implementation and administration of the amendments made by section 2 of this Act.