Detention

Definition

Detention is a charge the carrier levies when a container is kept outside the port or terminal beyond the allotted free time. It applies once the container leaves the terminal and has not been returned empty within the carrier's allowed window. Detention is distinct from demurrage, which applies while the container is still at the port.

Why it matters

Detention charges accrue daily and can exceed $200 per container per day after free time expires. At high container volumes, a single missed return deadline across a few shipments can wipe out the margin on those jobs. The ops team must track return deadlines per container, per carrier, across every active job.

How detention free time is calculated

Detention free time begins when the container is picked up from the terminal and ends when it is returned empty to the carrier's designated depot or gate. The free time allowance is set by the carrier's tariff or the negotiated service contract, typically 3 to 5 days. Some carriers count calendar days, some count business days, and the terms differ by trade lane and contract. A forwarder who assumes 5 days means business days on a carrier that uses calendar days may lose two days of usable free time over a weekend and not discover it until the invoice arrives.

Detention vs. demurrage in practice

Demurrage and detention are related but separate charges with separate clocks. Demurrage runs while the container is inside the port terminal, from the last free day until the container is picked up. Detention runs from pickup until the empty container is returned. It is possible for both clocks to be running if a container leaves the terminal late (accruing demurrage) and then takes too long to be emptied and returned (accruing detention). They are invoiced separately, often weeks apart, and both must be reconciled against the job before it is closed.

Returning containers and the empty-return process

Empty container returns require a return appointment at the carrier's depot, which may be a different location than the terminal where the container was picked up. During peak seasons or port congestion periods, return appointments can be difficult to obtain on short notice, which pushes the return date past the free time window through no fault of the consignee. Documenting the appointment request date and any carrier-side delays is necessary for disputing the resulting detention charge. Carriers are required under FMC rules to offer reasonable opportunities to return equipment, so a documented blocked return is a viable dispute.