Anyone shipping goods into the United States by sea runs into a requirement that has nothing to do with duties: the Importer Security Filing, usually called ISF or "10+2". It is a set of data about the shipment that has to reach U.S. Customs and Border Protection (CBP) before the cargo is even loaded onto the ship. Missing the timing is the common mistake, because the deadline falls at the foreign port, often before the importer has thought about customs at all. This guide sets out what 19 CFR part 149 requires, who has to file, and the two different deadlines.
Who Has to File, and for What
The rule applies to cargo arriving by vessel. The filing is required of the ISF Importer, defined in 19 CFR 149.1 as the party causing goods to arrive within the limits of a U.S. port by vessel. For most shipments that is the goods' owner, purchaser, consignee, or an agent such as a licensed customs broker. Under 149.2(a), the filing must be made in English through a CBP-approved electronic system, by the ISF Importer or an authorized agent.
Two preconditions apply. The party must have set up the electronic communication CBP requires (149.5(a)), and the ISF Importer must hold a bond of a type listed in 149.5(b), such as a basic importation and entry bond or an importer security filing bond. Bulk cargo that is exempt from the carrier's own 24-hour cargo declaration requirement is also exempt from the ISF (149.4(a)), and break bulk cargo gets a different timing rule (149.4(b)). The requirement in 149.2(a) is written for cargo arriving by vessel, so this guide does not cover shipments that arrive by truck or air.
The Ten Data Elements and Two Deadlines
The elements are listed in 19 CFR 149.3(a) and must be provided for each good at the six-digit tariff level, at the lowest bill of lading level. They fall into two groups by timing.
| Data element | Deadline (19 CFR 149.2(b)) |
|---|---|
| Seller | No later than 24 hours before the cargo is laden aboard the vessel at the foreign port |
| Buyer | Same |
| Importer of record number (or foreign trade zone applicant ID) | Same |
| Consignee number(s) | Same |
| Manufacturer (or supplier) | Same |
| Ship to party | Same |
| Country of origin | Same |
| Commodity HTSUS number (six digits required, ten allowed) | Same |
| Container stuffing location | As early as possible, and no later than 24 hours before arrival at a U.S. port |
| Consolidator (stuffer) | Same |
An example with made-up dates: a vessel is scheduled to load the cargo on Monday at 14:00 at the foreign port. The first eight elements must be submitted by 14:00 the previous Sunday. If the vessel then arrives at a U.S. port at 06:00 on the 18th, the container stuffing location and consolidator are due no later than 06:00 on the 17th. For a voyage under 24 hours, the rule ties that second deadline to lading at the foreign port instead.
Accuracy, Updates and Withdrawal
- What you can rely on. If a filer receives information from another party, CBP considers how, under ordinary commercial practice, the filer got it and whether the filer can verify it. Where the filer cannot reasonably verify it, the filer may submit what it reasonably believes to be true (149.2(c)).
- Updates. The filer must update the filing if, after submitting and before the goods enter the limits of a U.S. port, any information changes or more accurate information becomes available (149.2(d)).
- Flexibility on four elements. For manufacturer, ship-to party, country of origin and commodity number, an initial answer based on the best data available is permitted, to be updated as soon as better data exists, and in no event less than 24 hours before arrival (149.2(f)).
- Withdrawal. If the goods are no longer coming to the United States, the filer must withdraw the filing and give CBP the reason (149.2(e)).
A Short Checklist
- Ask the shipping line or forwarder for the vessel's loading date and work back 24 hours. Do this at booking, not at loading.
- Confirm who is filing: you, or your customs broker. Make sure the bond is in place.
- Gather the eight elements early. The manufacturer's name and address and the six-digit tariff number are the ones most often unknown at booking.
- Calendar the second deadline for the stuffing location and consolidator from the vessel's expected arrival.
- Keep the filing updated if the supplier, origin or classification changes.
Where This Guide Stops
This guide covers the filing requirement only. It does not cover the penalties CBP may assess for late or inaccurate filings, customs entry and duties, or the commercial terms that decide who pays for what on an international shipment. For the paperwork between a shipper and a carrier on the U.S. side, see Shipper, Carrier and Consignee: Who Does What in a Freight Shipment.
Sources
Regulation text: eCFR, current as of 7 October 2026. For a real shipment, a licensed customs broker can confirm how this applies.
