29 CFR §2570.84

1. (a)The civil penalty must be paid within 60 days of service of the notice of assessment.
2. (b)At any time prior to the expiration of the payment period for the assessed penalty, any person who has committed, or knowingly participated in, a breach or violation, or has been alleged by the Secretary to have so committed or participated, may submit a written request for a conference with the Secretary to discuss the calculation of the assessed penalty. A person will be entitled under this section to one such conference per assessment. If such written request is submitted during the 60 day payment period described in subparagraph (a), such a request will not toll the running of that payment period.
3. (c)The notice of assessment will become a final order (within the meaning of 5 U.S.C. 704) on the first day following the 60 day payment period, subject to any tolling caused by a petition to waive or reduce described in § 2570.85.