ISF, Bond and Demurrage: The Import Clock Before FBA

By Bernardo Campelo, Forbes Business Council E-Commerce Leader, Amazon SPN Certified provider, Amazon SP-API authorized partner, and Founder of PrepVia.

A seller calls us the week a container is supposed to arrive and asks a version of the same question every time. The container cleared the port three days ago, so why is inventory still not on a truck. The answer is rarely the ocean carrier and rarely the customs broker. It is usually a clock the seller did not know was running, and by the time anyone reads the invoice for it, the clock has already cost real money.

Most guidance about importing for Amazon FBA focuses on paperwork. What form to file, what the commercial invoice needs to say, whether the shipment travels DDP or DDU. Those questions matter, and we have written about them separately. This piece is about something different: the sequence of deadlines that starts before your container is even loaded and does not stop until inventory checks in at an Amazon fulfillment center, and the penalty attached to missing each one.

None of these clocks belong to PrepVia. We receive freight after most of them have already run. But sellers ask us about them constantly, because the dock is the first place the delay becomes visible, even when the cause sits three steps upstream.

The Clock Starts Before the Container Ever Loads: ISF

The first deadline in an ocean import has nothing to do with the ship, and it usually catches first time importers off guard for exactly that reason. The Importer Security Filing, commonly called ISF or "10+2" for the ten data elements the importer supplies and the two the carrier supplies, has to be transmitted to CBP at least 24 hours before the container is laden aboard the vessel at the foreign port. Not 24 hours before arrival in the United States. Twenty four hours before the box goes on the ship.

We covered the ISF filing requirement briefly in our guide to customs documents for an FBA import, and it is worth repeating here because of what it triggers downstream. A late, inaccurate or missing ISF filing carries penalties of up to 5,000 dollars per violation, and CBP can issue that penalty per filing error, not per shipment, so a single container with several data problems can generate more than one violation. Worse for a Q4 shipper, an unresolved ISF issue can hold a container for additional exam at the port, which burns through the free days described further down before the container has even reached your prep center.

The importer of record is the party responsible for the ISF, though in practice a licensed customs broker or freight forwarder usually transmits it on the importer's behalf using data the importer supplies. That data has to be accurate at the moment the container is booked, which means the filing deadline is really a planning deadline. If your supplier confirms a load date on a Tuesday, your broker needs the ISF data before that Tuesday, not after.

The Bond Behind Every Entry: Single Entry or Continuous

No formal entry clears CBP without a customs bond on file, and the bond question is really a question about how often you import, not how big any one shipment is. A single entry bond covers exactly one shipment and is generally priced against that shipment's value and estimated duties. A continuous bond covers every entry an importer files over a twelve month period, generally starts with a floor around 50,000 dollars in bond amount, and can be adjusted higher based on duties, taxes and fees paid in the prior year.

As a general pattern in the market, a continuous bond at the minimum face value carries an annual premium in the low hundreds of dollars, while a single entry bond is priced per shipment against value and duty exposure, and can end up costing more across three or four shipments a year than one continuous bond would for the same volume. Neither figure is fixed. Sureties price bonds against the importer's history, the product category, and the country of origin, and a first time importer with no track record generally pays more than an importer with several clean years on file.

The bond has to be active before the entry is filed, which means it belongs on the same pre-booking checklist as the ISF. A seller who waits until the container is on the water to ask about a bond is asking the question about two to three weeks too late, since underwriting a new continuous bond, particularly for an entity with no import history, can take longer than a single ocean transit.

Arrival, Discharge, and the Free Days Nobody Reads Closely

Once the vessel arrives and the container is discharged onto the terminal, a new clock starts, and this is the one most sellers have never heard of until they are already inside it. Ocean carriers and terminals grant a set number of free days before they start charging for a container that remains on their property. That window is commonly referred to as free time, and it typically runs somewhere in the range of four to seven calendar days, though the exact number depends on the specific carrier, the terminal, and the port, and can be shorter during periods of port congestion.

Free time does not wait for customs to finish. It starts on discharge, regardless of whether the entry has cleared, which is exactly why the ISF and the bond need to be settled before arrival rather than after it. A container stuck behind an unresolved entry is still burning free days while the paperwork gets sorted out, and those days do not come back once they are gone.

This is also where drayage capacity matters. Even a cleanly cleared entry needs a trucker to physically move the container off the terminal, and during peak shipping periods, trucking capacity in major ports can be tight enough that booking drayage a day or two in advance is not enough. A seller who assumes the container will simply move once customs clears it is skipping a step that has its own lead time.

Demurrage: The Terminal's Meter Once Free Time Runs Out

Demurrage is the fee a terminal or ocean carrier charges when a container remains on the terminal past its free time, still waiting for pickup. It is billed per day, per container, and it generally escalates the longer the container sits, with many carriers structuring it in tiers rather than a single flat rate.

As a general market range, import demurrage commonly runs somewhere between 150 and 300 dollars per day once it begins, and can climb higher on later tiers or during periods of terminal congestion when carriers raise rates to encourage faster pickup. These are market patterns, not a fixed schedule, and the actual number on any invoice depends on the specific carrier's tariff, the port, and the season.

Demurrage is generally the importer's liability, since it is the importer's cargo sitting on the terminal, though the exact contractual responsibility can shift depending on the terms negotiated with the freight forwarder. The practical fix is simple to state and harder to execute under pressure: have drayage booked and the entry filed before the vessel discharges, so the container moves inside the free window instead of after it.

Detention: The Meter That Starts After the Container Leaves the Port

Detention is a separate fee from demurrage, and the two get confused constantly because they sound like the same problem. Demurrage covers the container while it sits at the terminal. Detention covers the container once it has left the terminal on a truck chassis and is out being unloaded, generally at your warehouse or prep center, before it is returned empty to the carrier.

Ocean carriers typically grant a separate free time allowance for detention, often in a similar range to demurrage free time, and once that window closes, a per day detention fee begins, generally in a comparable market range to demurrage, again varying by carrier and contract. The practical driver here is turnaround at the receiving dock. A container that sits loaded in a parking lot for two extra days while a warehouse works through a backlog is generating detention charges the whole time, even though the terminal has already been paid and the entry has already cleared.

This is the piece of the clock that a prep center's receiving speed actually touches directly. Our facility runs three loading docks across 5,500 square feet in Miami, and container unloading starts from 400 dollars per container, with the goal of getting a container emptied and the chassis released inside our standard 24-36 hour window from the time the container lands on our dock, precisely because every extra hour a loaded container sits is an hour of detention exposure that belongs to the seller, not to us. Details on how we structure container receiving are on our import and export page.

Customs Release: The Step That Does Not Always Wait for You

Customs release is not a single moment so much as the outcome of everything upstream working correctly. When the entry is filed cleanly, the HTS classification is not in question, and the shipment is not selected for exam, release can happen within hours of the entry summary being processed. When any of those conditions is not met, release can take considerably longer, and the container keeps burning free days at the terminal the entire time.

CBP selects a portion of shipments for additional exam, and a shipment held for exam, whether a document review or a physical inspection, is effectively removed from the normal timeline until CBP releases it. There is no seller side lever that speeds this up once a container is flagged. The only real lever is upstream: accurate declarations, correct classification, and complete documentation reduce the odds of a hold in the first place, which is the whole argument for treating the paperwork stage as seriously as the freight stage.

A cleared entry with duties paid does not automatically mean the cargo is physically available. Release from CBP and release from the terminal are two different administrative steps, and a seller checking only one of them can be surprised when a container shows cleared in one system and unavailable in another for another day or two.

The Calendar: From Booking to Amazon Check-In

Laid out in order, the full sequence runs longer than most sellers picture when they are only thinking about ocean transit time. This calendar assumes a standard ocean shipment with no exam hold and reasonably prompt handling at each step, and it is meant to show where responsibility sits, not to promise a specific number of days for your shipment.

Two things stand out when the sequence is written this way instead of scattered across separate conversations with a broker, a trucker and a warehouse. First, four of the ten stages sit entirely with the importer or the importer's broker, which means the seller controls more of this timeline than the ocean transit portion suggests. Second, the two fee stages, demurrage and detention, are both avoidable with the same fix: have the paperwork and the drayage booked before the container needs them, not after.

Once inventory clears our dock, tracking shifts to a different set of milestones entirely, covered in our guide to FBA inbound shipment tracking, and confirming Amazon actually received what shipped is its own separate question, addressed in how to prove Amazon received your FBA shipment.

Frequently Asked Questions

What is the ISF filing deadline for an ocean import?

The Importer Security Filing must be transmitted to CBP at least 24 hours before the container is laden aboard the vessel at the foreign port. It is not tied to arrival in the United States, which is why the filing has to be handled at booking rather than closer to departure.

What is the difference between demurrage and detention?

Demurrage is the fee charged when a container remains at the terminal past its free time, still waiting for pickup. Detention is the fee charged once the container has left the terminal on a chassis and is out with the importer, generally at a warehouse, past its own separate free time, before it is returned empty to the carrier.

Do I need a customs bond for every shipment?

Every formal entry needs a bond in place, either a single entry bond covering that one shipment or a continuous bond covering all of an importer's entries over a twelve month period. A single entry bond is generally more expensive per shipment than a continuous bond once an importer is bringing in more than a few containers a year.

How many free days do I get before demurrage starts?

It varies by carrier, terminal and port, and commonly falls somewhere between four and seven calendar days, though it can be shorter during periods of port congestion. Confirm the specific allowance with your freight forwarder or broker for the exact carrier and route, since it is not a fixed government number.

Who pays demurrage and detention charges?

These charges are generally the importer's liability, since the container and its contents belong to the importer during both windows, though the specific contractual arrangement can shift responsibility to a freight forwarder or trucking partner depending on the terms negotiated for that shipment.

Can customs hold a container past its free time even if I did everything correctly?

Yes. CBP selects a portion of shipments for document review or physical exam regardless of how clean the paperwork is, and a held shipment sits outside the normal release timeline until CBP clears it. Accurate declarations and correct classification reduce the odds of a hold, but they do not eliminate the possibility entirely.

Does PrepVia handle ISF filing or customs bonds?

No. PrepVia receives and preps freight once it has cleared the port and reached our Miami dock. ISF filing, bond arrangements and customs entries are handled by a licensed customs broker, and that relationship should be in place before your container books space, not after it arrives.

Final Take

The mistake most first time importers make is not a document mistake. It is a sequencing mistake. They treat the import as one deadline, the arrival date, when it is actually five overlapping clocks that start at different moments and carry different penalties for running past them. The ISF clock starts at booking. The bond has to be settled before entry. The terminal's free time starts on discharge. The carrier's detention free time starts once the container leaves the terminal. Customs release depends on all of the above going cleanly.

None of these clocks are PrepVia's to run, and we are direct about that with every seller who asks us to explain a delay that started upstream of our dock. What we can control is our part: turning a container fast enough that detention exposure ends the moment it lands with us, not two days later. That is the entire logic behind our 24-36 hour prep window and why we built our receiving process around getting a container unloaded quickly once it reaches Miami.

If you are planning your next container, the fix is not complicated, even though it requires more upfront coordination than most sellers expect. Confirm your broker has ISF data before booking. Confirm the bond is active before the entry is filed. Book drayage before the vessel discharges instead of after. Every one of those steps happens before the container is anywhere near a warehouse dock, and every one of them determines whether your import runs on schedule or starts generating fees nobody budgeted for.

This article describes general market patterns in ISF, bond, demurrage and detention practice. It is not customs brokerage advice, and the specific deadlines, free time allowances and fee amounts that apply to your shipment depend on your carrier, your terminal, your broker and your contract. Confirm all of it directly with a licensed customs broker before you book.