How to Send Stock to a 3PL: ASNs, Carton Labels and Pallet Requirements for Every Inbound Delivery

To send stock to a 3PL, load your product data first, create an advance shipping notice (ASN) before the goods leave, label every carton with your company name, ASN reference, SKU and quantity, build pallets to the warehouse's rules and book a delivery slot. Then agree how you will be told the stock is sellable.

The first delivery to a new fulfilment partner tests both of you. Stock that arrives without notice, with unclear labels or on badly built pallets is slow to receive, expensive to sort and late to become available to sell. Many brands blame the warehouse when the cause is preparation upstream at the supplier.

Inbound is predictable, though. A short set of rules applied to every delivery removes most delays. This guide explains what an ASN should contain, how to label cartons and pallets, how different delivery types are handled and what to ask a prospective 3PL, including how its warehouse system and client portal handle pre-advice.

What Is an Advance Shipping Notice (ASN)?

An advance shipping notice, or ASN, is a message that tells the warehouse what stock is coming, in what quantities and when, before it arrives. Many UK warehouses call it a pre-advice.

The warehouse uses it to plan labour and dock space and, when the goods arrive, to compare what it counts with what you said was coming. Formats vary: some 3PLs use a portal form, others a spreadsheet upload or a system integration. The principle is the same everywhere, so ask for the exact process and template before your first delivery.

What Should an ASN Include?

A complete ASN allows the warehouse to receive your stock efficiently without needing to stop and request additional information. Missing or incomplete details are among the most common reasons deliveries experience delays at the receiving dock.

The ASN or purchase order reference connects the physical delivery to the corresponding record in the warehouse management system, ensuring the shipment can be identified and processed correctly. Including the supplier's details and expected delivery date allows the warehouse to plan labour requirements and allocate sufficient dock space ahead of arrival.

The delivery type and quantity, whether individual parcels, pallets or a full container, determine how the shipment needs to be booked, handled and unloaded. Providing carrier tracking numbers also allows the warehouse to match incoming deliveries to their expected records without additional manual checks.

Accurate SKU, barcode and quantity information for each product line is essential for verifying the stock received against the expected shipment. Where applicable, batch numbers and expiry dates should also be included so the warehouse can record this information during goods-in processing, supporting product traceability and effective stock rotation.

Finally, supporting documentation, such as packing lists and commercial invoices, helps warehouse teams investigate and resolve discrepancies quickly if the physical delivery does not match the ASN.

The ASN should be created before stock leaves your supplier, rather than when it arrives at the warehouse. If shipment quantities or other details change before delivery, the ASN should be updated to ensure the warehouse has accurate information when the stock arrives.

How Should Cartons Be Labelled?

Every carton should show your company name, the ASN reference, the SKU and the quantity inside, on a label that is readable and scannable from the outside. Cartons without this information have to be opened and identified by hand, which slows receiving and is often charged.

Keep one SKU per carton where you can. Mixed cartons are possible in most systems, but they need a clear contents label and take longer to count. Make sure the quantity on the label matches the paperwork, and send your labelling rules to the supplier or contract packer who applies the labels, because that is where most errors start.

Pallet Requirements and SSCC Labels

Pallets should be stable, wrapped, within the warehouse's height and weight limits and labelled on at least two sides. Ask your 3PL for its maximum height and weight, the pallet types it accepts and how it wants pallets wrapped.

If you supply retailers, your pallets may already carry GS1 logistics labels. GS1 UK explains that these labels carry a Serial Shipping Container Code (SSCC), an 18-digit number held in a GS1-128 barcode that identifies one pallet, with each pallet needing its own serial number. When the SSCC is also included in the ASN, a warehouse that supports it can receive a whole pallet or carton with one scan. Ask whether your 3PL can use SSCCs, because the work your supplier already does for retail compliance can speed up receiving too.

How Different Delivery Types Are Handled

The way stock arrives decides how it is booked and unloaded. Parcel deliveries of a few cartons rarely need a booking. Palletised freight usually needs a booked delivery slot, and freight that arrives unannounced may be turned away or held until a dock is free.

Containers from overseas suppliers arrive either palletised or floor-loaded with loose cartons. Floor-loaded containers take longer to unload and sort, so tell the warehouse which you are sending and agree the unloading charge in advance. For any delivery type, book early during peak months, when dock slots fill quickly.

Get Product Data Right Before the Stock Arrives

Stock cannot be put away or picked until each product exists in the warehouse system. Provide a unique SKU, a barcode that scans, dimensions, weight and any handling notes, such as fragile, batch controlled or date coded.

Mistakes at this stage become mistakes in every later order. If your products carry batch numbers or expiry dates, agree how they will be captured at goods in. If you are unsure whether your barcodes will work, check before the stock ships, not at the dock. Our guide to the fulfilment infrastructure a DTC brand needs in month one covers product data set-up.

Plan the Timing

Tell the warehouse when stock is due, not only when it arrives. If a launch or campaign depends on stock, allow time for goods in, checks, putaway and system updates.

Agree how quickly received stock becomes available to sell and how you will be told it has been booked in. Do not assume that a Monday delivery means orders can ship on Monday.

What Happens When a Delivery Does Not Match?

Counts will sometimes differ from the ASN, so agree upfront how short, over and unannounced deliveries are recorded and reported. A good process photographs discrepancies, records them against the ASN and tells you the same day.

Ask what happens to stock that arrives with no matching ASN, how long it is held and whether storage or handling charges apply. Damaged stock follows its own process; our guide to goods-in inspection when stock arrives damaged covers quarantine and supplier claims. Your finance team will want a clear record of every adjustment.

Questions to Ask a 3PL About Inbound

The answers show whether a warehouse can receive your stock quickly and accurately:

• Can we have your written inbound guide, including ASN template, carton labels and pallet rules?
• How do we submit an ASN: portal, file upload or integration?
• How are deliveries booked, and how much notice do you need?
• Can you receive using SSCC labels?
• How quickly is stock received and available to sell, and how are we told?
• What happens when a delivery does not match its ASN, or arrives without one?
• How are batch and expiry data captured?
• How is receiving charged, and what extra charges apply to non-compliant deliveries?
• Who looks after us during the first few deliveries?

Where Fulfil with Synergy Fits

Fulfil with Synergy, the Northampton-based third-party logistics provider, runs stock transfer and putaway through RedPrairie Dispatcher, which gives real-time visibility to unit, SKU, batch and location level and a full stock movement audit trail that is time-stamped and user-tagged. Its client portal lets brands create SKUs and manage pre-advice directly, so product data and ASNs are in place before stock arrives.

Systems connect through API, flat-file SFTP or SOAP web services, with technical documentation and hands-on support from in-house specialists, from onboarding engineers to WMS super users. Onboarding includes order flow testing, inventory sync checks and error handling before you go live. Our guide to what a fulfilment onboarding timeline looks like week by week shows where inbound sits in the plan, and the article on matching your tech stack to a provider's integration options explains the choices.

Every brand has dedicated account management, and Fulfil with Synergy has a dedicated onboarding manager, so the first deliveries are planned with people who are learning your products. When stock arrives from a supplier without the right labels, barcoding and re-labelling are handled in-house through value-added services. Fulfil with Synergy operates seven days a week from purpose-built facilities in Northampton with over 280 fulfilment specialists, supporting multi-channel and retail fulfilment. Ask the team for its inbound requirements before your first delivery, since specific rules depend on your products and volumes.

An Inbound Checklist

Run through these steps for every delivery:

1. Send product data and confirm it is loaded.
2. Create the ASN before the stock leaves the supplier.
3. Check carton labels against the ASN.
4. Build and label pallets to the warehouse's rules, with SSCCs if you use them.
5. Book the delivery slot.
6. Tell the warehouse when you need the stock to be sellable.
7. Review the first delivery together and fix what went wrong before the next.

FAQ

What is an ASN?

An advance shipping notice, or ASN, tells the warehouse what stock is coming, in what quantities and when, before it arrives. UK warehouses often call it a pre-advice. It lets the warehouse plan labour and dock space and compare what it counts with what was expected. A complete ASN includes a reference, supplier, expected date, delivery type, tracking numbers, SKUs, barcodes, quantities and any batch or expiry data. Create it before the goods leave your supplier and update it if quantities change.

What should be on a carton label?

Each carton should show your company name, the ASN reference, the SKU and the quantity inside, on a label that can be read and scanned from the outside. Some warehouses also ask for carton numbers, such as 3 of 12. Keep one SKU per carton where possible, because mixed cartons take longer to count and need a clear contents label. Send the warehouse's labelling rules to whoever packs the cartons, usually your supplier, so the labels are right before the stock ships rather than fixed at the dock.

What is an SSCC label and do I need one?

An SSCC label is a GS1 logistics label carrying an 18-digit Serial Shipping Container Code in a GS1-128 barcode, which identifies a single pallet or carton. Many retailers require them. You do not usually need one to send stock to a 3PL, but if your supplier already applies SSCCs for retail customers, a warehouse that supports them can receive a pallet with one scan when the SSCC is included in the ASN. GS1 UK members can create logistics labels using GS1's own tools.

Do I need to book a delivery slot?

Usually yes for palletised freight and containers. Most warehouses run a booking system so they have the right people and dock space ready, and freight that arrives without a booking may be turned away, rescheduled or held until a dock is free. Parcel deliveries of a few cartons rarely need a slot. Ask your 3PL how much notice it needs, how bookings are made and what happens if the haulier arrives late, and book early in peak months, when slots fill quickly.

How long before stock is available to sell?

It depends on the warehouse, the delivery type and how well it was prepared. A correctly labelled delivery with a complete ASN moves through goods in much faster than one that needs identifying by hand. Ask for a clear target for receipt to sellable, and agree how you will be told stock has been booked in. Allow extra time for floor-loaded containers, batch-controlled stock and peak periods, and do not plan a launch on the assumption that stock delivered in the morning will ship that afternoon.

If you are planning your first delivery to a new warehouse, talk to Fulfil with Synergy about inbound requirements and onboarding.

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