Shipper's Letter of Instruction
What Is an SLI — and How Do You Fill One Out?
The SLI is the instruction sheet you give your freight forwarder. Get it wrong and you get a wrong Bill of Lading. Here's every field explained.
What is an SLI?
A Shipper's Letter of Instruction (SLI) is a document you complete and give to your freight forwarder authorising them to arrange shipment on your behalf and providing all the information they need to prepare the Bill of Lading, book the cargo, and file export declarations. It is not a contract of carriage — it is an instruction document. Think of it as the master source of truth from which your forwarder derives all other shipping documents.
Why it matters
Errors in the SLI flow directly into the Bill of Lading, AES/EEI export filing, and sometimes the commercial invoice. A wrong description, incorrect HS code, or missing marks and numbers can cause customs holds, carrier fines, delays at destination, and LC discrepancies. The SLI is the first document in the export chain — errors here multiply downstream.
Field by Field
Every SLI Field Explained
SLI formats vary by forwarder, but these fields are standard across all versions.
Shipper / Exporter
Your full legal company name and address exactly as it appears on your commercial invoice and as registered with customs. Do not use trading names or abbreviations unless they match your customs registration. This name will appear on the Bill of Lading as the shipper.
Consignee
The party who will receive the goods at destination — usually your buyer. Include full legal name, address, and contact details. For Letter of Credit shipments, the consignee field on the B/L must match the LC instructions exactly — often 'To the order of [Bank Name]' rather than the buyer directly.
Notify party
The party the carrier notifies when cargo arrives. Usually the consignee or their customs broker at destination. For LC shipments, the notify party is typically the buyer even if the consignee is the issuing bank. This field does not transfer title — it is purely an arrival notification.
Port of loading
The port where cargo is loaded onto the vessel. Must match the actual port your freight forwarder will use. For inland container depots (ICD), specify the ICD name and the actual loading port separately if your forwarder requires it.
Port of discharge
The destination port where the cargo will be unloaded from the vessel. Not the final delivery point — just the port. Specify the correct port code and country. Errors here can result in cargo being discharged at the wrong port.
Description of goods
A specific, accurate description of the cargo. Not generic terms like 'merchandise' or 'goods' — that triggers customs queries. Use the commercial description, e.g. 'Men's cotton woven shirts, 65% cotton 35% polyester.' Under US CBP rules, vague descriptions are a violation. Some forwarders will not accept non-specific descriptions.
HS code (Schedule B / HTS)
The 6-digit (international) or 10-digit (US Schedule B / HTS) commodity classification code. Used for export declaration, determining duty rates at destination, and statistical tracking. An incorrect HS code can cause mis-classification, duty disputes, and delays. When in doubt, use a licensed customs broker to verify.
Marks and numbers
The shipping marks printed on the outside of your cartons — typically your company name/logo, destination, PO number, carton numbers (e.g. 1/20, 2/20). Must match exactly what is physically on the boxes. The B/L, commercial invoice, and packing list must all reference the same marks and numbers.
Number of packages and kind
Total number of cartons, crates, pallets, or other packages and their type. E.g. '120 cartons' or '4 wooden pallets.' This goes directly onto the B/L. If palletised, declare both the number of pallets and the number of cartons on the pallets.
Gross weight and net weight
Total gross weight (cargo + packaging) and net weight (cargo only) in kilograms or pounds as agreed. Must match the packing list. Significant discrepancies between declared and actual weight can result in freight adjustment charges or customs queries.
Measurement (CBM)
Total cubic volume of the shipment in cubic metres (CBM). Used to calculate chargeable weight for air freight and to verify container utilisation. Must match the packing list. Calculate as length × width × height (in metres) × number of cartons.
Declared value for carriage
The value you declare for the carrier's liability purposes — not necessarily the commercial invoice value. If left blank, liability defaults to the Hague-Visby or COGSA limit (approximately $500 per package or 2 SDR per kg). Declaring a higher value may increase freight charges but provides better carrier liability coverage.
Dangerous goods indicator
Whether the shipment contains any dangerous goods (DG) per IMDG or IATA regulations. If yes, a separate DG declaration and MSDS must accompany the SLI. Incorrect DG declaration is a serious offence — carriers can refuse cargo and authorities can impose significant fines.
Freight payment terms
Whether freight is prepaid (paid by shipper) or collect (paid by consignee at destination). Must align with the Incoterm in the sales contract. FOB = freight collect is typical; CIF/CFR = freight prepaid. Mismatched freight terms cause disputes on arrival.
Special instructions
Any special handling, stacking, temperature, or documentation requirements. Include LC number and issuing bank if applicable, certificate of origin requirements, fumigation requirements, or any special cargo handling needs. This is also where you instruct the forwarder on whether to use a House B/L or Master B/L.
Common Errors
The Most Frequent SLI Mistakes
These errors appear repeatedly and almost always cause downstream problems.
Consignee name doesn't match LC
For LC shipments, the consignee on the B/L must match the LC wording exactly — including punctuation and company designation (Ltd vs Limited vs LLC). Even minor differences are discrepancies that can delay or prevent payment.
Vague goods description
'General merchandise,' 'spare parts,' or 'as per invoice' are not acceptable descriptions for most customs authorities or carriers. Use the specific commercial description from your invoice.
Wrong HS code
Using a broad or incorrect HS code to reduce duty rates is customs fraud. Beyond compliance risk, wrong codes cause mis-classification at destination and can trigger inspections, delays, and fines.
Marks don't match physical cartons
The shipping marks in the SLI must exactly match what's printed on the boxes. If you change your labelling, update the SLI. Discrepancies cause problems during customs examination.
Freight terms mismatch
Declaring freight prepaid when the buyer expects to pay at destination (or vice versa) leads to disputes, additional fees, and delays in cargo release.
Missing DG declaration
Failing to declare dangerous goods — including lithium batteries, chemicals, and certain paints — is a serious compliance breach. Penalties can include cargo seizure, vessel fines, and shipper blacklisting by carriers.
Connected Documents
How the SLI Connects to Other Documents
The SLI is the source document. Everything else flows from it — errors in the SLI become errors in all these.
Bill of Lading
The forwarder uses the SLI to prepare the B/L. Shipper, consignee, notify party, goods description, marks, weight, and volume all come directly from the SLI. The B/L is the contract of carriage — getting the SLI right gets the B/L right.
AES / EEI Export Filing (US)
For US exports valued over $2,500 (or requiring an export licence), the forwarder files the Electronic Export Information (EEI) in AES using the SLI data — including the HS Schedule B code, shipper EIN, and consignee details. Errors here are federal violations.
Commercial Invoice
The goods description, HS code, declared value, and party details on the SLI must be consistent with the commercial invoice. Customs at destination cross-checks these documents — inconsistencies trigger queries.
Packing List
The number of packages, marks and numbers, gross weight, and CBM in the SLI must match the packing list exactly. The three documents (SLI, commercial invoice, packing list) form a triangle — all must agree.
Certificate of Origin
If you instruct the forwarder to obtain a certificate of origin (CoO), the goods description and shipper details on the CoO are derived from the SLI. Required for preferential tariff claims at destination.
FAQ