Your arrival notice lists a Last Free Day. You book the trucker against it, pick up with a day to spare, and an invoice still lands a week later. The reason is simple and counterintuitive: the LFD on that notice is one clock. It may not be the only clock that can bill you.
Many arrival notices show a port-side or demurrage-related LFD — the deadline tied to the container sitting at the terminal. The charge that often catches importers later is detention or per diem: the carrier’s clock on its equipment after the box leaves the terminal. That clock is set by the line’s tariff or contract, and it may not be visible on the notice you’re reading. If you’re managing only the printed LFD, you may be managing the wrong deadline.
Two charges, two clocks
The two fees get used interchangeably in hallway conversation, but they bill for different things and may be governed by different parties, tariffs, or systems.
Demurrage is a charge for use of terminal space after free time expires. Depending on the port, tariff, and billing setup, it may be assessed directly by the marine terminal operator or invoiced by the carrier/NVOCC. Detention or per diem is the charge for extended use of the carrier’s equipment once the box is off the terminal. One bills for the container remaining in the port-side system; the other bills for holding the line’s equipment.
FMC guidance treats cargo availability for retrieval as a key reasonableness factor under 46 CFR 545.5. In plain operational terms: a charge is supposed to serve an incentive purpose when cargo can actually be retrieved. But the clock you see in practice still depends on the applicable tariff, terminal status, carrier rule, and billing party.
The three-clock map
If your container rails inland, there may be a third clock — the railroad’s. Three clocks, three owners, three start-events. This is the table worth bookmarking.
| Clock | Who controls or invoices it | Charge | What STARTS it | Where you read it | How it ENDS |
|---|---|---|---|---|---|
| Terminal / demurrage | Marine terminal operator and/or carrier/NVOCC, depending on tariff and billing setup | Demurrage — container remaining in the terminal system past free time | Container discharged and available for retrieval, subject to tariff and terminal rules | Terminal portal, port/terminal tariff, carrier tariff, or arrival notice LFD | Box out-gates from the terminal |
| Carrier / detention or per diem (focus) | Ocean carrier, under line tariff or contract | Detention/per-diem — extended use of the carrier’s equipment off-terminal | Laden equipment out-gate or interchange, depending on carrier rule | Carrier’s D&D tariff, contract, or per-B/L lookup. Often not shown on the arrival notice | Empty return / empty gate-in at the approved return location |
| Rail (intermodal) | Railroad or inland terminal operator | Rail storage/demurrage on equipment at the ramp | Notification that the box is grounded and available, subject to railroad tariff | Railroad tariff, ramp portal, or intermodal provider portal | Box out-gates from the rail ramp |
Why the clocks diverge
These clocks were not designed to line up neatly. Each has its own owner, tariff basis, source system, and start event — discharge-and-availability for the terminal, laden out-gate or interchange for the carrier, grounded-and-notified for the rail. There is no single mechanism keeping them in sync, so by default they often do not match.
Three things widen the gap in practice. First, feed lag: a terminal availability feed can trail a carrier or EDI event, so one system may show the box available while another still looks incomplete. Second, missing data: some terminals or ports do not expose a clean LFD in a way your team can reliably monitor. Third, basis mismatch: free time counted in working days versus calendar days differs by carrier, port, terminal, rail ramp, and contract. The same nominal “five free days” can expire on different real-world dates depending on whose clock you’re reading.
Stack those together and the practical result is that the deadline printed on your notice and the deadline that actually drives an invoice can be different dates.
The carrier/detention clock up close
Since detention/per-diem is often the clock hardest to see, it is worth knowing how the major lines structure it. The starts and bases differ by name — this is operator detail, not boilerplate.
CMA CGM should be checked by market and tariff. In U.S. tariff materials, import free days are commonly counted in working days, while chargeable days after free time expires are billed in calendar days. That means the count to your deadline may skip non-working days, but the meter after expiry may not. Do not generalize that globally: CMA CGM uses different D&D structures in different markets, including merged D&D in some locations.
Hapag-Lloyd uses calendar-day charging in its U.S. detention/demurrage framework after free time expires. Certain customs-hold scenarios are treated under specific rules — for example, detention treatment may depend on whether the container is held outside the terminal or at a customs warehouse. The important point is not that every hold automatically stops the clock; it is that hold location, release status, and tariff language determine how days are counted.
ONE ties U.S. detention/per-diem treatment to the laden container out-gate or interchange event, with tariff-specific rules for free time and chargeable days. California empty-return and per-diem treatment can differ, so the current tariff and return instructions matter. The operational mistake is assuming the terminal LFD also tells you the empty-return deadline. It usually does not.
Maersk‘s U.S. import detention clock starts when equipment departs the carrier’s container yard and ends when the empty container is gated in at the agreed return location. Maersk shifted U.S. post-free-time D&D charging to a calendar-day basis in August 2024, and its later tariff updates changed rates while leaving free-time allowances unchanged unless otherwise specified. As with every carrier, confirm the current tariff per lane rather than assuming one rule applies everywhere.
One terminology note that trips people up: “LFD” and “Last Free Day” are not formal DCSA event terms. What DCSA standardizes is events — including AVPU, “Available for Pick-up.” In practice, many carrier and terminal systems still expose discharge, release, gate, and availability events more clearly than a single standardized AVPU-style milestone. So when you compare an “LFD” from one source against another, you may be comparing different underlying events that happen to share a familiar label.
On the regulatory side, the FMC’s Part 541 billing rules have been in effect since 28 May 2024: required invoice elements, a 30-day issuance window, and a dispute window of at least 30 days. If required invoice information is missing, the billed party has no obligation to pay the applicable charge. Worth knowing for contesting a bad invoice — but note that §541.4, the who-may-be-billed provision, was vacated effective 29 Dec 2025. The rest of the rule survives; do not build any dispute argument on §541.4.
If your team is reconciling these per-carrier clocks by hand against a notice that only shows one of them, walk through how ops teams set up container-level detention alerts across carriers.
What you can control, and what you can’t
Some of this is structural and you simply have to plan around it. The rest is genuinely yours to manage — and the leverage is in not confusing the two.
Controllable. Customs clearance timing is partly yours. Clearing early reduces exposure, but a government hold does not automatically stop every D&D clock. The tariff, hold location, appointment availability, and carrier policy determine how the days are treated. Pickup planning is also yours: book against the earliest operational deadline you can identify, not just the one printed on the arrival notice. And empty-return timing is the move that ends the detention/per-diem clock entirely — getting the empty box back to the approved return location, not merely pulling the laden box out of the terminal, is what stops the line’s equipment meter.
Uncontrollable. The multi-party structure is not going to align itself for you. Terminal, carrier, and rail clocks can each start from different events. Feed lag between terminal and carrier systems is not something you can close from your desk. And ports or terminals that do not publish a clean LFD leave a gap you cannot fill by trying harder; you can only route around it by reading the carrier, terminal, and rail clocks directly.
A hedge worth stating plainly, because it is easy to overclaim: “the earliest clock binds” is an operating heuristic, not a legal rule. Demurrage, detention, terminal storage, and rail storage each depend on their own tariff, contract, and factual event chain. No statute makes the soonest clock controlling across all charges. Treat “earliest clock” as the date to plan against, not a legal position to argue.
The deadline you can’t see is the one to find
The failure mode is consistent: teams chase the deadline printed on the arrival notice and get billed on a clock that was not visible there. Avoiding that means knowing which clock applies to the specific charge: terminal demurrage, carrier detention/per-diem, terminal storage, or rail storage. That cannot be read off a single document, because no single document reliably holds all of them.
It requires reconciling the container’s event chain — discharge, availability, release, laden out-gate, rail grounding, rail out-gate, empty return — against the applicable carrier, terminal, and rail rules. The work has to happen continuously, at the container level, because the invoice is built from events, not from the deadline your team happened to notice first.
That reconciliation is exactly what continuous multi-carrier visibility does. Tradlinx Ocean Visibility pulls those events into one view across carriers and flags exceptions as a clock approaches expiry — so the deadline that actually drives the invoice is the one you’re planning against, not only the one that happens to be on the notice.
Related reading
- The Demurrage & Detention Blame Game: Legal Pitfalls in D&D Disputes Shippers Need to Know
- Demurrage, Detention, Free Time: Definitions and Cost Reduction Strategies
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