29 C.F.R. § 2520.104-41

(a) General.

(b) Application. The administrator of an employee pension or welfare benefit plan which covers fewer than 100 participants at the beginning of the plan year and the administrator of an employee pension or welfare benefit plan described in § 2520.103-1(d) may file the simplified annual report described in paragraph (c) of this section in lieu of the annual report described in § 2520.103-1(b).

(c) Contents. The administrator of an employee pension or welfare benefit plan described in paragraph (b) of this section shall file, in the manner described in § 2520.104a-5, a completed Form 5500 “Annual Return/Report of Employee Benefit Plan” including, if applicable, the information described in § 2520.103-1(f) or, to the extent eligible, a completed Form 5500-SF “Short Form Annual Return/Report of Small Employee Benefit Plan,” and any required schedules or statements prescribed by the instructions to the applicable form, and, unless waived by § 2520.104-44 or § 2520.104-46, a report of an independent qualified public accountant meeting the requirements of § 2520.103-1(b).