45 C.F.R. § 91.43
(a) HHS will promptly refer to a mediation agency designated by the Secretary all sufficient complaints that:
(e) The mediation will proceed for a maximum of 60 days after a complaint is filed with HHS. Mediation ends if:
(3) Prior to the end of that 60-day period, the mediator determines that an agreement cannot be reached.
This 60-day period may be extended by the mediator, with the concurrence of HHS, for not more than 30 days if the mediator determines that agreement will likely be reached during such extended period.