20 C.F.R. § 422.603
Our notice of assignment will inform you as the assigned operator (or related person) which beneficiaries have been assigned to you, the reason for the assignment, and the dates of employment on which the assignment was based. The notice will explain that, if you disagree with the assignment for any beneficiary listed in the notice of assignment, you may request from us detailed information as to the work history of the miner and the basis for the assignment. Such request must be filed with us within 30 days after you receive the notice of assignment, as explained in § 422.604 . The notice will also explain that if you still disagree with the assignment after you have received the detailed information, you may submit evidence that shows there is a prima facie case of error in that assignment and request review. Such request must be filed with us within 30 days after you receive the detailed information, as explained in § 422.605 . Alternatively, you may request review within 30 days after you receive the notice of assignment, even if you have not first requested the detailed information. In that case, you still may request the detailed information within that 30-day period. (See § 422.606(c) for further details.)
20 C.F.R. §422.603