29 C.F.R. § 2570.87
If, based on the procedures described in § 2570.84 , 2570.85 , or 2570.86 , the assessed penalty amount is revised, the person being assessed will receive a revised notice of assessment and will be obligated to pay the revised assessed penalty within the relevant 60 day payment period (as determined by the applicable procedure in § 2570.84 , 2570.85 , or 2570.86 ), and, if necessary, any excess penalty payment will be refunded as soon as administratively feasible. The revised notice of assessment will revoke any previously issued notice of assessment with regard to the transaction in question and will become a final order (within the meaning of 5 U.S.C. 704 ) the later of the first day following the 60 day payment period or the date of its service on the person being assessed, pursuant to the service procedures described in § 2570.83(b) .
29 C.F.R. §2570.87