Demurrage

1. What is demurrage?

Demurrage is a per-day charge billed when a container, trailer, or railcar is held beyond the free time a carrier or terminal allows for loading or unloading. It is distinct from detention, which applies to equipment held away from the terminal, and from storage, which applies to cargo left at a facility. Rates and free-time windows are set in the carrier's tariff or, where one exists, in the shipper's negotiated contract.

The charge exists to keep terminal space and equipment moving. A carrier allows a set number of free days for loading, unloading, or return, and once that window closes, a daily rate applies until the equipment clears.

The free-time count and the daily rate are the two variables that matter, and both are negotiable. A contract with a carrier can extend free time from the tariff default or set a lower per-day rate, but the invoice generated at the terminal often applies the public tariff by default rather than the negotiated one.

2. How does demurrage differ from detention and storage?

Demurrage applies to equipment held at the terminal or port past free time. Detention applies once that same equipment leaves the terminal and is held elsewhere, at a warehouse or distribution center, past its allowed return window. Storage is a separate charge for cargo left on a dock or in a yard.

Invoices sometimes label these interchangeably, which is itself a source of billing error worth checking before a charge is approved.

Demurrage appears on the terminal or steamship line invoice. Detention appears on the trucking or drayage invoice once equipment is off-site. Storage is billed separately by the facility holding the cargo, and can stack with either of the other two if a shipment is delayed at multiple points in the chain.

Confirming which charge type actually applies, and to which leg of the movement, is the first step before checking whether the rate itself is correct.

3. Why does demurrage drift from the contract rate?

Demurrage drift happens because the invoice is generated by the terminal's or carrier's billing system, which applies its own default free-time and rate table unless someone forces it to reference the negotiated contract. A contract clause specifying extended free time or a discounted per-day rate does not automatically propagate into that billing system, so invoices settle at the higher, unmodified tariff rate.

Three mechanisms account for most of the gap between an invoiced demurrage charge and the contract terms behind it: a free-time miscount that treats weekends, holidays, or facility closures as chargeable days when the contract excludes them; a tariff default applied because the negotiated per-day rate was never loaded into the carrier's billing system; and a wrong start date, where the clock begins at vessel arrival or gate-in instead of the trigger event the contract actually defines.

Each is a mismatch between what the contract says and what the billing system defaults to, not a pricing dispute over the rate itself.

4. How should an AP team audit demurrage charges?

Auditing demurrage means pulling the free-time and rate clause for the specific carrier and lane, checking the invoiced start and stop dates against actual gate-in and gate-out or pickup records, and confirming the per-day rate matches the contract rather than the default tariff. This is a line-by-line check against a document that usually sits outside the ERP, which is why it gets missed during routine invoice approval.

The check is mechanical once the contract terms are in hand: compare the invoiced free-time window to the negotiated one, compare the daily rate charged to the rate on file, and confirm the trigger date used for the clock matches the contract's definition rather than the carrier's default.

This is the same logic applied across a broader freight and 3PL audit, where demurrage is one line item among several accessorial charges reviewed against the underlying rate agreement rather than accepted as billed.

For the wider pattern this sits inside, start with the margin drift guide.

5. Frequently Asked Questions (People Also Ask)

Is demurrage the same as a late fee?

No. A late fee applies to a delayed payment. Demurrage applies to cargo or equipment held past its free-time window, regardless of whether any invoice has been paid late.

Who sets the demurrage rate?

The carrier or terminal publishes a tariff rate, but a shipper with a negotiated contract may have a different, usually lower, rate written into that agreement. The invoice should reflect the contract rate, not the public tariff, when a contract exists.

Can free time be extended by negotiation?

Yes. Free-time windows are a standard negotiation point in carrier contracts, alongside the daily rate charged once that window closes. The extension only holds if the carrier's billing system is actually configured to apply it.

Does three-way matching catch demurrage overbilling?

Three-way matching confirms the invoice ties to a purchase order and a receipt. It does not test whether the free-time count or the per-day rate applied matches the carrier contract, because that contract typically lives outside the ERP.

What documents are needed to check a demurrage charge?

The carrier or terminal contract showing the negotiated free-time and rate clause, and the gate-in, gate-out, or pickup records showing the actual dates the equipment was held, are both needed to verify a demurrage line against what was actually agreed.

Is demurrage a form of accessorial charge?

Yes. It is one of several charges layered onto a base freight rate, alongside items like fuel surcharges and detention. Accessorial charge creep describes how these charges accumulate beyond what a contract authorizes.

Does demurrage apply to trucking as well as ocean freight?

Demurrage most commonly applies to ocean containers and rail, at the port or terminal. Equipment held past free time once it leaves that terminal is typically billed as detention rather than demurrage, even though the underlying mechanism, a daily charge for a delay, is similar.

Where does demurrage fit in the broader margin drift picture?

Demurrage is one specific drift type within indirect spend. Distinguishing a genuine rate change from a billing error on a recurring charge like this one is the same test applied to margin drift generally.