19 C.F.R. § 351.210
(b) Deadline for final determination. The deadline for a final determination under section 705(a)(1) or section 735(a)(1) of the Act will be:
(2) In an antidumping investigation, not later than 135 days after the date of publication of the preliminary determination if the Secretary postpones the final determination at the request of:
(4) In a countervailing duty investigation, the same date as the date of the final antidumping determination, if: