49 CFR § 1333.3 - Who is subject to demurrage.
(a) Any person receiving rail cars from a rail carrier for loading or unloading who detains the cars beyond the period of free time set forth in the governing demurrage tariff may be held liable for demurrage if the carrier has provided that person with actual notice of the demurrage tariff providing for such liability prior to the placement of the rail cars. The notice required by this section shall be in written or electronic form.
(b) If the rail cars are delivered to a third-party intermediary that has reached an agreement with a shipper (or consignee) that the shipper (or consignee) shall be billed for demurrage, then the serving Class I carrier shall, after being jointly notified of the agreement by the shipper (or consignee) and third-party intermediary, bill the shipper (or consignee) for demurrage charges without requiring the third-party intermediary to act as a guarantor, unless and until a party to the agreement notifies both the serving Class I carrier and the other party to the agreement that the agreement is no longer in force. Pursuant to this paragraph, the shipper (or consignee) shall be liable to the Class I carrier for demurrage but shall not be prohibited from seeking payment from the third-party intermediary for demurrage charges for which the third-party intermediary is responsible pursuant to an agreement between the shipper (or consignee) and the third-party intermediary. The joint notice required by this paragraph may be provided in hard copy or electronic form, and must contain the contact information for the shipper (or consignee) who has agreed to be billed (and liable to the Class I carrier) for demurrage and provide the date upon which the Class I carrier is to begin billing the shipper (or consignee) for demurrage (no earlier than 20 days after the notice is provided). With respect to Class I carriers' obligations for direct billing, a statement from one party that the agreement has been terminated is sufficient to end the direct-billing requirement, regardless of any disputes as to the sufficiency of the termination under the terms of the specific agreement between the shipper (or consignee) and third-party intermediary.