Shipper's Letter of Instructions (SLI): Definition, Template, Field Guide
The Shipper's Letter of Instructions authorises a freight forwarder to file export declarations on your behalf. Includes required fields, common errors, and free template.
Try the calculator
Run a real calculation for this lane in under a minute. Free, no card.
Open calculatorShipper's Letter of Instructions (SLI)
A Shipper's Letter of Instructions, usually abbreviated SLI, is a signed authorisation from the exporter of record to a freight forwarder. It gives the forwarder the legal right to prepare and file export documents (most importantly the Electronic Export Information in AES) on the exporter's behalf, and it locks in the shipment-specific facts the forwarder will use: routing, Incoterms, HTS or Schedule B classification, and licence citations.
What the SLI does in practice
Three functions in one document:
- Authorisation. Without an SLI (or a broader Power of Attorney), a US freight forwarder cannot lawfully file EEI through the Automated Export System under 15 CFR 30.3.
- Shipment record. The SLI captures every declaration-critical fact in one place so the AES filing and the commercial invoice do not diverge.
- Compliance evidence. BIS and Census audits rely on the SLI to prove the exporter had a chain-of-custody for the classification decision.
Required and recommended fields
Fields the SLI must carry for a US export:
- USPPI name, address, EIN or tax ID
- Ultimate consignee name, address, country
- Forwarder name, filer ID
- Mode of transport and carrier SCAC
- Port of export and country of ultimate destination
- Schedule B or HTS-10 code per commodity line
- Value and unit of quantity
- Incoterms 2020 term and named place
- ECCN or EAR99, licence type (NLR, Licence Exception TSU, or licence number)
- Routed transaction flag (US or foreign PPI-controlled)
- Signature and date
Optional but recommended: hazmat flag, IATA UN number, temperature range, insurance basis (CIF vs. FOB math), notify-party details for the destination broker.
Common SLI errors that trigger a hold
The four most-cited by Census AESDirect fatal-error logs:
- Schedule B does not match the HTS in the commercial invoice. Census cross-checks against USITC and rejects mismatches at the 6-digit level.
- Ultimate consignee is a freight forwarder, not the actual buyer. This is a "known" pattern for diversion risk and prompts a manual review.
- ECCN missing when the HTS chapter maps to a controlled category (Chapters 84/85/90 electronics, 87 vehicles, 88 aircraft). AES will not accept "EAR99" for these without an internal classification memo.
- Value declared FOB when the Incoterm is CIF. The value on the AES filing is FAS (free alongside ship) plus inland freight to port; add-ons above that must be documented, not assumed.
Related: DDP, Incoterms, and landed cost
The Incoterm named in the SLI drives who is the importer of record on the buyer side, which in turn drives the landed cost calculation. Use the LandedFees calculator to model DDP vs. FOB vs. CIF outcomes before you finalise the SLI Incoterm field.
Primary sources
- 15 CFR Part 30, Foreign Trade Regulations, Subpart A: ecfr.gov
- Census AESDirect user guide (2024 revision): census.gov
- 2013 SLI template reissue announcement, US Census Foreign Trade Division
Frequently asked questions
Is a Shipper's Letter of Instructions legally required?
The SLI itself is not a US statutory form, but a written authorisation is required whenever a US Principal Party in Interest (USPPI) asks a freight forwarder to file the Electronic Export Information (EEI) through AES. Without a signed SLI or Power of Attorney the forwarder cannot legally act as the filer on your behalf under 15 CFR Part 30.3.
What is the difference between an SLI and a Power of Attorney?
A Power of Attorney is a broad legal delegation, often multi-year, that lets a forwarder or broker sign customs documents in your name. An SLI is shipment-specific: it names the freight, the routing, and the classification for one export and typically expires when that shipment clears.
Who needs to sign the SLI?
The USPPI (or an officer legally authorised to act for the USPPI). A shipping coordinator's signature is fine if the company has delegated export-compliance authority to that person in writing.
What fields must appear on the SLI?
USPPI name and EIN, ultimate consignee, forwarder details, mode of transport, Schedule B or HTS code, ECCN or EAR99, license or licence-exception citation, Incoterms, value, and a routing instruction. The 2013 US Census reissue is the field template most forwarders still use.
Does the SLI have to travel with the cargo?
No. It is a filer-authorisation document between shipper and forwarder. Physical shipping paperwork travels with the freight, but the SLI stays with the forwarder's compliance file. Retention: 5 years from date of export per 15 CFR 30.10.
Ready to calculate?
Get a real number for your shipment in under a minute.
Free, no card, full breakdown of duty, VAT, freight, and fees.
Related guides
Process and How-To
TEU (Twenty-Foot Equivalent Unit): Meaning, Math, Container Fits
A TEU is the standard container unit: one 20-ft ISO box equals 1 TEU, a 40-ft equals 2 TEU. Includes vessel capacity math and payload examples.
Process and How-To
DDP (Delivered Duty Paid): Meaning, Risk Transfer, and When to Use It
DDP is the Incoterm where the seller pays freight, insurance, import duty, and taxes and delivers cleared goods to the buyer's door. Includes DDP vs DAP comparison and landed cost math.
Process and How-To
USMCA Certificate of Origin Template: 9 Required Data Elements
USMCA does not require a specific form for the certification of origin. It requires 9 specific data elements per Article 5.2. Here is the field list, the per-element format, and a downloadable template that satisfies CBP, CBSA, and SAT requirements.
Process and How-To
Type 86 Entry in 2026: Requirements After the De Minimis Reset
Type 86 is the streamlined low-value entry process in ACE. After the May 2025 Section 321 China suspension and 2026 framework changes, here is what Type 86 currently allows, the value threshold, the filer rules, and the duty math.