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The simple operational distinction

Demurrage

Generally tied to cargo/container time at the marine terminal after applicable free time.

Container detention

Generally tied to extended use of the ocean carrier's container/equipment after it leaves the terminal.

Per diem

An industry term commonly used for a daily equipment-use charge. Exact contract/addendum terminology matters.

Terminal storage

A terminal/facility storage charge. It may be separate from a carrier's demurrage/equipment charge.

Driver detention

A trucker's waiting-time charge.

That is why saying “we got hit with detention” is not enough.

Ask: who charged it, for what asset/location, and for which dates?

Free time

Free time is the period before the applicable charge begins.

It is not universal.

It can depend on:

  • ocean carrier,
  • terminal,
  • service contract,
  • tariff,
  • import/export,
  • container type,
  • port,
  • holiday/weekend rules,
  • availability.

The relevant system may show a Last Free Day or free-time expiration.

Record it.

Why demurrage exists

The FMC's framework is built around freight fluidity: charges should encourage timely cargo movement and equipment return.

In July 2026, the D.C. Circuit upheld an FMC determination that detention fees charged during a three-day port closure were unreasonable when the trucker had no practical ability to return the equipment. That illustrates the core principle: the charge should have a real incentivizing connection to moving freight/equipment.

Do not rely on an old summary saying the FMC's 2024 rule still specifies exactly who may receive a D&D invoice.

In September 2025, the D.C. Circuit set aside 46 CFR 541.4, the section that specified who may be billed.

The FMC says the remainder of the rule remains in effect.

That includes requirements such as:

  • invoice timing,
  • required invoice information,
  • processes affecting fee mitigation/refund/waiver.

The FMC has said it is revisiting the billing-party issue.

For current disputes, use the current rule/guidance rather than an older blog summary.

Invoice timing still matters

Under the surviving FMC framework, VOCCs and marine terminal operators generally must issue covered D&D invoices within 30 calendar days after the charges were last incurred; NVOCC timing works differently when it receives an underlying invoice.

The current regulation/guidance should be checked for the actual invoice.

What should be on the invoice?

The FMC requires sufficient identifying information for covered invoices, including information that allows the billed party to understand the charge and dispute/mitigation process.

For a shipper, the practical audit questions are:

  • Which container?
  • Which dates?
  • Which free-time period?
  • What rate?
  • What event started/stopped the clock?
  • Was the container/equipment actually available for movement?
  • How do I dispute or request mitigation?

What evidence should you save?

When a container is at risk of D&D, save:

  • availability screenshots,
  • hold status,
  • appointment searches,
  • appointment confirmations,
  • terminal closure notices,
  • empty-return instructions,
  • rejected return screenshots,
  • emails/tickets,
  • gate transactions,
  • timestamps.

If a dispute occurs, contemporaneous operational evidence is more useful than trying to reconstruct the week later.

Example

Import container:

Monday discharged Tuesday — customs hold clears Wednesday — available; terminal shows LFD Friday Thursday — appointment booked Friday — gate out Monday — unload complete Tuesday — empty returned

Potential clocks could involve:

  • terminal/free-time clock before gate-out,
  • container/equipment-use clock outside terminal,
  • separate dray carrier waiting/storage if used.

The actual charge structure depends on the applicable parties' terms.

How to reduce exposure

  • monitor availability daily as vessel works,
  • know LFD,
  • book appointments early,
  • clear Customs/carrier holds early,
  • plan chassis,
  • use a pre-pull when operationally justified,
  • schedule warehouse receiving before pickup,
  • know empty-return location before delivery,
  • document failed attempts.

Bottom line

Do not argue over the label first.

Identify:

asset → location → dates → free time → rate → billing party → operational ability to move

That tells you what you are actually looking at.

Related:

Watching a last free day?

Send the container, terminal and free-time dates and we will help you see which clock is running and what still has to happen before it stops.

Request a Freight Quote

Official references

  • FMC D&D page: https://www.fmc.gov/detention-and-demurrage/
  • FMC 2025 court decision: https://www.fmc.gov/articles/u-s-court-of-appeals-issues-decision-in-case-on-demurrage-and-detention-billing-practices/
  • FMC 2026 detention decision: https://www.fmc.gov/articles/u-s-court-of-appeals-upholds-fmc-decision-that-detention-fees-must-promote-freight-fluidity/
  • FMC audit best practices: https://www.fmc.gov/databases-and-publications/vessel-operating-common-carrier-vocc-audit-program/