How sea cargo moves

Written for someone who has to file and has not spent a career in a shipping line. Everything below is about the ordinary case: a container arriving in India.

The people involved

A single box has more parties attached to it than seems reasonable, and the declaration asks about most of them.

Shipper / consignor — who sent the goods.Consignee — who receives them. On an import filing this is normally an Indian company with a PAN.Notified party — who the carrier tells on arrival. Very often the same as the consignee.Carrier / shipping line — owns or operates the vessel. Issues the master bill.Freight forwarder / consolidator / NVOCC — books space with the carrier and sells it on to many shippers. Issues house bills. This is who this product is built for.Sea agent — files on the carrier's behalf at a particular port.Transhipper — the party bonded to move cargo onward from the port of arrival to an inland station.

The two levels of bill of lading

This is the single most important shape in the whole message, and the one most often got wrong.

A master bill of lading is issued by the carrier for a container, to the forwarder. A house bill of lading is issued by the forwarder to each individual shipper whose goods are inside that container. One master can carry many houses — that is exactly what consolidation means — or none at all, when the whole box belongs to one shipper.

In the SCMTR message this is a nesting, not two lists:

master
  mastrCnsgmtDec[]          ← master consignments (one per master B/L)
    MCRef                     the master B/L's own reference
    trnsprtEqmt[]             containers at master level
    houseCargoDec[]         ← house bills, INSIDE their master
      HCRef                   the house B/L's own reference
      trnsprtDoc              the parties for this house bill
      itemDtls[]              what is actually in it
      trnsprtEqmt[]           containers at house level
      itnry[]                 the route

House bills are not a separate top-level list. If you find yourself filing a house bill without a master above it, something has gone wrong.

A master with no house bill is completely normal. A full-container load for one shipper has one master and no houses. Both shapes appear in filings customs has accepted.

Is there a limit on how many house bills one master can carry — is it six?

Asked in the trade on 2026-09-19 ("does ICEGATE permit only up to 6 HBLs?"). No — accepted filings go well past six. Among the accepted CSNs on record, single master bills carry 7, 8, 12 and 16 house bills, each accepted by customs in one filing, and we know of no notice or guide that sets a limit of six. If a filing with more than six house bills is refused, read the code on the acknowledgement — it will name the actual fault (most often one house bill's own combination, party or container rows), which a house-bill count would not explain.

Containers appear at both levels — deliberately

The same container number is declared on the master consignment and on each house bill inside it. That is not a duplicate: the master says "this box exists on this bill", and each house says "my goods are in that box".

Weights are where this bites. The master's container weight is the whole box. Each house's container weight is only that house's share of it. On a consolidation with four house bills the four house weights sum to the master's — and customs cross-checks that.

Where the cargo goes after it lands

Two ports are recorded, and they are frequently different:

First port of entry — where the vessel discharges it. The B/L calls this the port of discharge (POD).Destination / next port of unlading — where it is finally cleared. destPrt is the closest thing the message has to the B/L's final place of delivery (FPOD), with one difference that matters: it holds a customs location — port, ICD, CFS or SEZ code — so a door or inland-town FPOD is filed as the customs station where clearance happens. See which port goes in which field.

If they match, the cargo is cleared where it lands: local clearance (crgoMvmt: LC). If they differ, it moves onward under bond to another customs station: transhipment inbound (TI). An inland container depot — INDER6 (Dadri), INTKD6 (Tughlakabad) — is the usual onward destination, reached by rail or road.

Watch for the sub-location case. INMAA1 → INMAA1TCF1 looks like the same place and is not: the box still moves from the port into a specific facility, which is still a bonded movement.

The itinerary

The route as a list of legs, each with its own port of call, next port of call and mode of transport. A typical import: Hamburg → Ennore by sea (modeOfTrnsprt: 1), then Ennore → Chennai by road (3) or rail (2). The mode belongs to the leg, not the filing.

What a CSN is, and when it is due

The Cargo Summary Notification is the advance declaration of what is on board. Under SCMTR it is filed before arrival, so customs knows what is coming rather than finding out at the quayside. Once accepted, customs grants a CSN number — the identifier every later message about that cargo refers back to.

The filing chain around it:

The carrier files the arrival manifest (SAM) for the vessel.Each consignment's CSN is filed against it.Customs accepts, and issues the CSN number, and often an MCIN/PCIN.Anything that changes afterwards is an amendment referencing that CSN — never a new filing.

Reference numbers you will be asked for, and where they come from

The IMO number is worth understanding: it identifies the hull for life, regardless of renaming or reflagging, which is why customs prefers it to a vessel name.

The size-type code deserves a word too, because it is the one field on a container where filers genuinely disagree with each other. It is optional, customs publishes no list of valid values, and different lines send different codes for boxes of the same nominal size — a real carrier filing in front of us declares its 20-foot containers under three different codes in a single message. Take it from the box or from the liner rather than from what a 20-footer is "usually" called, and never from commercial shorthand like 40HC, which is a booking label and not a code. Coded values works through what has actually been filed.

Weights, counts and the things customs cross-checks

Package counts on the document must equal the sum of the item package counts.Container weights at house level must sum to the master's.The declared totals — totalNmbrOfLines, totalNoOfTrnsprtEqmtMnfsted — must match how many are actually in the message.Container numbers must pass the ISO 6346 check digit.

These are arithmetic, so they are worth getting right before submitting rather than after a rejection.

Why any of this is exacting

A CSN is a legal declaration to customs, and a rejected one is not just a form to redo: the cargo can sit. That is why the details above — which level a container is declared at, whose PAN goes where, whether the destination is really the same port — matter more than they look.