49 CFR 375.807 - What actions may I take to collect the charges upon my freight bill?
(b) The credit period must be seven days (including Saturdays, Sundays, and Federal holidays).
(1) You must automatically extend the credit period to a total of 30 calendar days for any shipper who has not paid your freight bill within the 7-day period. However, for charges for impracticable operations that are not collected at delivery, you may not extend the credit period beyond 30 days after you present your freight bill.
(2) You will assess a service charge to each individual shipper equal to one percent of the amount of the freight bill, subject to a $20 minimum charge, for the extension of the credit period. You will assess the service charge for each 30-day extension the charges go unpaid.
(3) You must deny credit to any shipper who fails to pay a duly-presented freight bill within the 30-day period. You may grant credit to the individual shipper when the individual shipper satisfies he/she will promptly pay all future freight bills duly presented.