Shipper's Letter of Instruction (SLI)
A Shipper's Letter of Instruction (SLI) is a document in which the shipper formally instructs its freight forwarder on how to handle a shipment. It sets out the shipper, consignee and notify party, a description of the goods, the routing and mode, the Incoterms, and how the documents (such as the bill of lading) should be prepared — and often authorises the forwarder to act as the shipper's agent, including filing the export declaration.
The SLI is essentially the shipper's order sheet to the forwarder: it gives the forwarder the accurate details and authority needed to book carriage, prepare documentation and complete customs formalities correctly. A clear, complete SLI prevents errors and misunderstandings that would otherwise cause wrong bills of lading, mis-declared exports and delays. It is a routine but foundational document at the start of the export process.
Almost every documentation error downstream — a wrong consignee on the B/L, a mis-filed export declaration — traces back to unclear instructions at the start. The SLI is where the shipper gets those instructions right and gives the forwarder authority to act, making it a small document that prevents a lot of expensive mistakes.
What does a shipper's letter of instruction contain?
The parties, goods description, routing, Incoterms and instructions on how to prepare the documents, often authorising the forwarder to act as agent.
Who issues the SLI?
The shipper (exporter) issues it to its freight forwarder at the start of a shipment.