26 C.F.R. § 35.3405-1
The following questions and answers relate to withholding on pensions, annuities, and other deferred income under section 3405 of the Internal Revenue Code of 1986, as added by section 334 of the Tax Equity and Fiscal Responsibility Tax Act of 1982 (Public Law 97-248 ) (TEFRA).
a-1 through d-34 [Reserved]. For further guidance, see § 35.3405-1T .
d-35. Q. Through what medium may a payor provide the notice required under section 3405 to a payee?
A. A payor may provide the notice required under section 3405 (including the abbreviated notice described in d-27 of § 35.3405-1T and the annual notice described in d-31 of § 35.3405-1T ) to a payee on a written paper document. However, see § 1.401(a)-21 of this chapter for rules permitting the use of electronic media to provide applicable notices to recipients with respect to retirement plans and individual retirement plans.
26 C.F.R. §35.3405-1