The Three Charges That Quietly Drain Your Import Budget
Most importers know these fees exist. Few understand exactly how they work. Even fewer know how to fight them.
Demurrage, detention, and per diem are three separate charges. They are often confused, sometimes lumped together, and almost always avoidable — if you know the rules. Missing the distinction can cost you $150 to $450 per container per day, and those days add up fast at congested ports like Los Angeles/Long Beach, New York/New Jersey, or Savannah.
Here is exactly how each one works, who is legally responsible, and what you can do about it.
Demurrage: The Port's Clock
Demurrage is a fee charged by the ocean carrier (or terminal operator) when a full import container is not picked up from the terminal within the carrier's free time window.
Free time is typically 4 to 5 calendar days at major U.S. ports, though it varies by carrier and trade lane. Some carriers offer as few as 3 days on Asia-to-U.S. routes during peak season.
How It Accrues
The clock starts the moment the container is discharged from the vessel and made available for pickup — not when the vessel arrives, not when your customs entry is filed. It starts at availability.
Rates typically run:
- Days 1–3 over free time: $75–$150/container/day
- Days 4–6: $150–$250/container/day
- Day 7+: $250–$450/container/day
On a 40-foot container sitting 10 days past free time, you could easily owe $2,500–$4,000 to a single carrier before you've even touched the cargo.
Who Owes It
The merchant — which under most carrier bills of lading means the shipper, consignee, or notify party — is contractually liable. In practice, the consignee (the U.S. importer) is the party the carrier pursues. This is codified in the carrier's tariff, which is a legally binding document filed with the Federal Maritime Commission (FMC).
Under 46 U.S. Code § 41102, ocean carriers must publish their rates and rules in a publicly accessible tariff. If a carrier charges demurrage that is not in their tariff, they are in violation of federal law — and you have grounds to dispute.
Common Triggers
- CBP holds: Customs exams (VACIS, CET, tailgate) can freeze a container for 3–10+ days. The carrier's clock does not stop.
- ISF penalties: A late or inaccurate Importer Security Filing can trigger a hold at no fault of the trucker or importer's operations team.
- Documentation errors: A missing or incorrect commercial invoice, packing list, or certificate of origin delays entry filing and thus pickup.
- Port congestion: When terminals are backed up, appointment systems break down. Containers sit — and the meter runs.
Detention: The Carrier's Clock on Empty Equipment
Detention is the fee charged when a carrier's container — after it has been picked up from the terminal — is not returned empty within the carrier's free time for detention.
This charge has nothing to do with the port. It is about how long you are keeping the carrier's equipment outside the terminal gate.
How It Accrues
Detention free time typically runs 3 to 5 business days from the date of pickup, though again this varies by carrier and is specified in their tariff. The clock starts when the trucker picks up the container.
Detention rates are similar to demurrage:
- $75–$200/container/day at major carriers, escalating over time.
If your warehouse is slow to unload, your drayage provider holds the container over the weekend, or you need extra time to sort through a large shipment, those days are being counted.
Who Owes It
Again, the consignee is almost always the party the carrier bills. However, if a freight forwarder or customs broker arranged the shipment under a house bill of lading, liability can shift depending on the contractual arrangement.
One critical nuance: if your trucker picked up the container but then held it in a yard waiting for a delivery appointment at your warehouse, that detention accrual may be the trucker's fault — not yours. Get the pickup and delivery timestamps in writing before paying anything.
The FMC's 2020 Interpretive Rule
In May 2020, the FMC issued an Interpretive Rule on Detention and Demurrage (Docket No. 19-05). It stated that detention and demurrage charges must serve their intended purpose: incentivizing the movement of cargo and equipment. If a charge accrues during a period when the merchant had no reasonable ability to pick up or return the container (e.g., the terminal was closed, appointments were unavailable, CBP held the cargo), then the charge may be unreasonable under federal standards.
This rule is your primary legal lever when disputing charges. Document every appointment attempt, every CBP notification, every terminal closure. The FMC has since pushed this further with Fact Finding Investigation 29 (FFI-29), which specifically examined unreasonable detention and demurrage practices during port congestion.
Per Diem: The Rail and Chassis Clock
Per diem is frequently confused with detention, but they are different in origin and who charges them.
Per diem comes in two primary forms:
1. Rail Per Diem
When cargo moves by intermodal rail (e.g., from the Port of Los Angeles to a Chicago ramp), the railroad charges per diem on containers that are not unloaded and returned to the ramp within the free time — typically 48 to 72 hours after the container is available at the inland ramp. Rates vary but typically run $100–$200/day.
2. Chassis Per Diem
If a shipper or trucking company is using a chassis provided by a chassis pool (such as DCLI, TRAC Intermodal, or Flexi-Van), the chassis provider charges a daily rental fee — often called per diem — for every day the chassis is out of the pool. Rates run approximately $20–$40/day per chassis.
At first glance, $20/day looks minor. But if your trucker dropped a container at your warehouse on a chassis and your team took 12 days to unload and return it, that's $240–$480 in chassis per diem alone — on top of any detention charges still running from the carrier.
Who Owes Per Diem
For rail per diem, the intermodal marketing company (IMC) or the ocean carrier who booked the intermodal leg is typically billed first, and they pass the cost down to the consignee or freight forwarder via their tariff or contract.
For chassis per diem, the trucking company is directly liable to the chassis pool — but that cost is almost always passed through to the importer as a line item on the drayage invoice. Review every drayage invoice. Line items like "chassis split," "chassis usage," and "chassis per diem" are often legitimate but sometimes inflated or doubled.
How These Three Fees Interact on a Single Shipment
Here is a realistic scenario for a 40-foot container importing garments from Vietnam via LA/LB:
- Vessel arrives: Day 0
- Container available: Day 2
- Free time (demurrage): 4 days — expires Day 6
- CBP selects for exam: Day 3. Exam completed Day 8.
- Trucker picks up: Day 9 (first available appointment)
- Container delivered to warehouse: Day 10
- Detention free time: 4 days from pickup — expires Day 13
- Container returned empty: Day 16
Demurrage owed: Days 7–9 = 3 days. At escalating rates ≈ $600–$900 Detention owed: Days 14–16 = 3 days ≈ $300–$600 Chassis per diem: Days 10–16 = 6 days × $30 = $180
Total: $1,080–$1,680 on one container. Scale that across 10 shipments per month and you're looking at a six-figure annual drag.
How to Dispute These Charges
Step 1: Request the Carrier's Tariff
Every charge must be grounded in the carrier's published tariff. Request it. Verify that the rate they billed matches what is in the tariff at the time of the shipment. Errors are more common than you think.
Step 2: Build Your Timeline
Gather timestamps from your customs broker (entry filing date), your trucker (pickup and delivery receipts), the terminal (availability and gate-out records), and CBP (any hold or exam notifications). If the container was held by a government agency or the terminal had no available appointments, document it precisely.
Step 3: File a Formal Dispute
Send a written dispute to the carrier's demurrage/detention billing department — not to your freight forwarder. Reference the FMC's 2020 Interpretive Rule and any specific dates when the container was beyond your reasonable control. Carriers are increasingly required to have transparent dispute resolution processes under the Ocean Shipping Reform Act of 2022 (OSRA-2022), which was signed into law in June 2022.
Step 4: Escalate to the FMC if Needed
If the carrier refuses to adjust an unreasonable charge, you can file a complaint with the Federal Maritime Commission at fmc.gov. The FMC has authority to investigate and impose penalties on carriers who levy charges that violate their tariff or federal standards.
Prevention Is Cheaper Than Disputes
- Align your customs broker's entry filing timeline with your carrier's free time. If free time is 4 days, your entry should be filed before the vessel arrives.
- Pre-arrange drayage before the vessel docks. Appointment slots at terminals like LBCT or APM fill within hours of availability.
- Audit every drayage invoice. Chassis per diem, split fees, and waiting time are frequently billed in error.
- Negotiate free time in your service contract. If you ship volume (10+ containers/month with a single carrier), you have leverage to negotiate 7–10 days of demurrage free time in your annual service contract under 46 CFR Part 530.
- Track container availability in real time. Tools like project44, Vizion, or your carrier's portal show availability dates. Set alerts so your ops team is not caught off guard.
The Bottom Line
Demurrage is about getting the container out of the terminal. Detention is about getting the container back to the carrier. Per diem is about the chassis and rail equipment you're holding onto. Each fee has a different clock, a different owner, and a different legal basis.
Know who is charging what, verify it against their published tariff, and document every moment the delay was outside your control. That discipline alone can save most importers $10,000–$50,000 per year.
Ready to stop losing money to container fees? Work with Regenerate Trade to audit your shipping costs and build a dispute-ready logistics process. Get started today.