Build the EDI 309 customs manifest transaction set with the M1 segment containing the standard carrier alpha code (SCAC), conveyance reference number, and country codes
Populate the CR1 and CR2 loops for each cargo release line with the bill of lading number, piece count, weight, and commodity description
Include the N1 and N9 loops to identify shipper, consignee, and reference numbers (master bill, house bill) for each cargo line item
Transmit the 309 via AS2 or SFTP to the customs broker's EDI gateway or directly to a CBP-authorized manifest management system within the required advance cargo notice window
Monitor for the 997 functional acknowledgment and any CBP response messages indicating holds or additional examination requirements
Known gotchas
EDI 309 is a customs manifest transaction set used for ocean and rail modes; air cargo manifests use different CBP messaging via the Air Cargo Advance Screening (ACAS) program
The SCAC code in the M1 segment must match the operating carrier's registered SCAC exactly; an incorrect SCAC will cause the manifest to be unmatched with the carrier's vessel or conveyance record
Manifest amendments after submission require a replacement 309 with a change reason code; not all CBP-connected systems support amendment; confirm the process with the receiving broker before filing
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp