Returns on Form W-2 required to be filed pursuant to the provisions of this section shall be transmitted by Form W-3. In a case where, with respect to the same employee, an employer must make a return on Form W-2 under this section and also under § 31.6011(a)-4 or § 31.6011(a)-5 of this chapter (Employment Tax Regulations), or under § 1.6041-2 (relating to return of information as to payments to employees), such employer may make such returns on the same Form W-2 or on separate Forms W-2. In a case where an employer must file a Form W-3 under this section and also under § 31.6011(a)-4 or § 31.6011(a)-5 of this chapter (Employment Tax Regulations), the Form W-3 filed under such § 31.6011(a)-4 or § 31.6011(a)-5 shall also be used as the transmittal form for a return on Form W-2 made pursuant to the provisions of this section.
26 C.F.R. §1.6052-1