29 C.F.R. § 4010.10

(a) Due date. Except as permitted under paragraph (b) of this section, a filer must file the information required under this part with PBGC on or before the 105th day after the close of the filer's information year. The filing deadline is extended to the 106th date after the close of the filer's information year if the 105-day reporting period includes February 29.

(b) Alternative due date. A filer that includes the statement specified in § 4010.8(b)(2)(i) with its submission to PBGC by the date specified in paragraph (a) of this section must submit the actuarial information specified in § 4010.8(b)(2) within 15 days after the deadline for filing the plan's annual report (Form 5500 series) for the plan year ending within the filer's information year (see § 2520.104a-5(a)(2) of this title).

(c) How and where to file. PBGC applies the rules in subpart A of part 4000 of this chapter to determine permissible methods of filing with PBGC under this part. See § 4000.4 of this chapter for information on where to file.

(d) Date of filing. PBGC applies the rules in subpart C of part 4000 of this chapter to determine the date that a submission under this part was filed with PBGC.

(e) Computation of time. PBGC applies the rules in subpart D of part 4000 of this chapter to compute any time period under this part.