A Shipper’s Letter of Instruction (SLI) is a document the exporter gives its freight forwarder that spells out exactly how a shipment should be handled: who the parties are, how it should route, who pays which charges, and who is authorized to file export data with the U.S. government. Think of it as the master brief for your export — when the SLI is complete and accurate, everything downstream (booking, bills of lading, customs filings) goes faster.
What an SLI contains
While formats vary, a solid SLI includes the exporter (USPPI) and consignee details, a precise cargo description with Schedule B or HS code, weights and dimensions, declared value, Incoterms, insurance instructions, hazardous-material declarations where applicable, and the forwarder’s authorization to act on the shipper’s behalf.
EEI filing authorization
For most exports over $2,500 per Schedule B line, Electronic Export Information (EEI) must be filed in the Automated Export System (AES). The SLI typically grants the forwarder power of attorney or written authorization to file, and records whether the transaction is routed (foreign buyer controls) or standard (U.S. shipper controls).
Routing and payment instructions
The SLI tells the forwarder which carrier, mode, or transit time you expect, whether to prepay or collect freight, and how to disposition documents — details that prevent expensive guesswork and disputes later.
Why the SLI matters
Export penalties are real: incorrect or late AES filings can draw fines per violation, and vague cargo descriptions invite holds. A good SLI protects the exporter by creating a written record of instructions, and protects the forwarder by defining the scope of its authority. It also speeds up document turnaround for the bill of lading and any consular or destination paperwork.
SLI vs. other export documents
The SLI is an internal instruction document — it does not travel with the cargo. The commercial invoice states the sale; the packing list describes the physical shipment; the bill of lading or air waybill is the carrier contract. The SLI is what makes sure all of those get produced correctly. Exporters using an NVOCC or forwarder for consolidated ocean freight should issue one per shipment rather than relying on emailed fragments.
How Go Freight supports Miami exporters
Go Freight works alongside freight forwarders every day, providing the physical execution behind the paperwork: export crating, cargo pickup on 100+ owned trucks, consolidation and staging in our 104,000 sq ft bonded Miami warehouse, and delivery to PortMiami, Port Everglades, or MIA. Clean instructions plus asset-based execution keep export bookings on schedule.
Frequently asked questions
Is a Shipper’s Letter of Instruction legally required?
No law mandates an SLI, but it is the standard way to authorize your forwarder to file EEI in AES and to document your routing and payment instructions. Many forwarders will not move a shipment without one.
Who fills out the SLI?
The exporter (the U.S. Principal Party in Interest) completes and signs the SLI, then sends it to the freight forwarder before the shipment is booked.
Do I need a new SLI for every shipment?
Best practice is one SLI per shipment. Some shippers issue a standing SLI for repetitive, identical shipments, but any change in commodity, value, or routing should trigger a fresh document.
Exporting through South Florida? Request a quote or call (786) 445-0150 for crating, bonded warehousing, and port drayage under one roof.