49 C.F.R. § 1300.4 – Notice requirement.

(a) A rail carrier may not increase any rates or charges, or change any service terms (except for changes that are equivalent to rate reductions), unless 20 days have expired after written or electronic notice has been provided to all persons who, within the previous 12 months:
1. (1) Have formally requested under ;§ 1300.2 or § 1300.3 of this part the affected rates or service terms; or
2. (2) Have made arrangements with the carrier for a future shipment that would be subject to the increased rates or changed service terms.
(b) The notice required by this section may be in written or electronic form, as agreed to by the parties. If the parties cannot agree, the information is to be provided in electronic (non-passive) form where both parties have the requisite capabilities; otherwise, it is to be provided in writing.
(c) For purposes of this section, a mailed notice is deemed “provided” on the date such notice is postmarked.
(d) The notice required by this section must clearly identify the increases in rates or charges or the changes in service terms.