Demurrage vs detention: what you are charged for, and how to avoid it

Both are charges for the use of a shipping line’s container or a terminal’s space beyond the free time, and US rules treat them together. The difference is where the container is:

• Demurrage: the full container is still in the terminal after the free time. For an import, Maersk counts it from discharge off the ship to the container leaving the gate full, minus the free days.
• Detention: you have taken the container out of the terminal and keep it beyond the free time. For an import, from leaving the gate full to returning it empty, minus the free days.

Free time is the number of days the container may sit in the terminal, or stay with you, before charges start. It is set by the line’s tariff or your forwarder’s contract and varies by port and line, so ask for it in the quote, in days, for both demurrage and detention.

• Customs holds and exams that keep the container at the port.
• An ISF or entry filed late, or a document missing at arrival.
• No truck booked to collect the container in time.
• A warehouse, or an Amazon fulfilment centre, with no delivery appointment for days.
• Slow unloading and returning the empty container late.

Since 28 May 2024, the Federal Maritime Commission’s billing rule (46 CFR part 541) sets what an invoice from a shipping line, terminal or NVOCC must contain. Among other things:

• The bill of lading and container numbers, and why you are the party billed.
• The free time allowed in days, its start and end dates, and the dates charged.
• The rate or rates and the tariff or contract they come from.
• A contact and a way to dispute the charge.
• A statement that the billing party did not cause the charges.

The invoice must be issued within 30 calendar days of the day the charge was last incurred; if it is not, you do not have to pay it. A charge missing the required information also need not be paid, though it can be reissued on a proper invoice.

You have at least 30 calendar days from the invoice date to ask for mitigation, a refund or a waiver, and the billing party must try to resolve it within 30 days. You can also file a charge complaint with the FMC, where the carrier has to prove its demurrage or detention charges are reasonable.

The rule’s section on who may be billed was struck down by a US court in September 2025; the rest of it stands.

• File the ISF and entry early, with complete documents. See ISF filing.
• Book the truck and the delivery appointment before the ship arrives.
• Ask for the free days in writing, and for more if the delivery is to an Amazon fulfilment centre.
• Unload quickly and return the empty container on time.
• Check each invoice against the FMC list before paying.

A carrier that wants to add a cost after the award, such as longer waiting, has to ask you with the reason and the figures, and nothing is charged unless you accept. When customs stops a shipment, who bears the hold follows its cause. See Can the carrier add charges after I accept? and Customs stopped my shipment.