One-line definition: A packing slip lists what is in the parcel for the recipient; a shipping label tells the carrier where to deliver it; an invoice is the financial record of the transaction between buyer and seller.
What they mean
All three documents are generated as part of the same order fulfillment process, and all three relate to the same shipment — but they serve completely different purposes and go to different audiences.
Packing slip A packing slip is a document placed inside the parcel. It lists the items included in the shipment — product names, SKUs, quantities — and typically includes the order number, the customer's delivery address, and sometimes a returns instruction. Its audience is the customer. It helps the recipient verify that everything they ordered is in the box, and gives them the information they need if they want to make a return. It does not show prices.
Shipping label A shipping label is applied to the outside of the parcel. It tells the carrier everything they need to deliver the parcel — the recipient's name and delivery address, the sender's return address, the carrier's routing barcodes, the tracking number, and service level information. Its audience is the carrier and the carrier's sorting systems. The barcodes on a shipping label are what allow automated sorting hubs to route the parcel through the network to its destination without human intervention.
Invoice An invoice is the financial document for the transaction — it records what was purchased, at what price, and the total amount owed or paid. For B2C e-commerce, an invoice is typically sent digitally to the customer after purchase. For B2B transactions, the invoice is the formal payment request. For international shipments, the commercial invoice is a customs document — required by customs authorities to assess duties and taxes on goods crossing a border. Its audience is the customer (for payment and tax records) and customs authorities (for international shipments).
Why it matters for e-commerce merchants
Confusing these three documents — or omitting one when it is required — creates specific, predictable problems.
A missing packing slip means the customer cannot easily verify their order is complete, cannot identify which order a return relates to, and has a less professional unboxing experience. For merchants who care about brand presentation, the packing slip is a touchpoint — an opportunity to include a thank-you note, a discount code for a repeat purchase, or clear returns instructions.
A missing or incorrect shipping label means the parcel cannot be delivered. It is the single document the carrier depends on entirely. A label with a wrong postcode, a smudged barcode, or the wrong service code will misroute, be delayed, or be returned.
A missing commercial invoice on an international shipment means the parcel will be held at customs until documentation is provided — or returned to the sender. For B2B customers, a missing VAT invoice causes administrative problems with their accounting. For international shipments, the commercial invoice is not optional.
The key differences at a glance
| Packing slip | Shipping label | Invoice | |
|---|---|---|---|
| Goes | Inside the parcel | On the outside of the parcel | Sent digitally / inside parcel / customs pouch |
| Audience | Customer | Carrier and sorting systems | Customer, customs authorities |
| Contains prices | No | No | Yes |
| Required for | Good customer experience | Every shipment | B2B, VAT records, international customs |
| Generated by | Merchant / fulfillment system | Carrier (via merchant booking) | Merchant / accounting system |
The commercial invoice — the international variant
For domestic shipments, the invoice is primarily a financial document. For international shipments crossing a customs border — any shipment from an EU country to the UK, Norway, or the USA, for example — the commercial invoice becomes a customs document as well as a financial one.
A commercial invoice for an international shipment must include:
- Seller and buyer name and address
- Invoice date and order reference number
- Description of each item (specific, not vague)
- HS tariff code for each item
- Country of origin for each item
- Quantity and unit price for each item
- Total goods value and currency
- Shipping cost (some customs authorities include this in the dutiable value)
- Signature or declaration of accuracy
This is more detailed than a standard domestic invoice and is what customs authorities use to calculate import duties and VAT. An incomplete or inaccurate commercial invoice is the most common cause of customs delays on international shipments — more than missing CN22/CN23 forms, which are often generated automatically, and more than incorrect addressing.
Pro forma invoice — a related document
A pro forma invoice is a preliminary version of a commercial invoice, sent before goods are shipped — typically to obtain payment, a letter of credit, or import permits. It looks like a commercial invoice but is labelled "pro forma" to indicate it is not a final billing document.
Pro forma invoices are most relevant for B2B international trade where buyers need documentation before authorizing payment or import clearance. For standard B2C e-commerce, pro forma invoices are rarely required — the standard order confirmation serves the same pre-shipment documentation function.
Common misconceptions and mistakes
"The packing slip and invoice are the same document." They are not. A packing slip does not show prices — it is a contents list for the customer. An invoice shows prices — it is a financial record. Combining the two into a single document (a "packing slip / invoice") is common in B2B e-commerce but for B2C, many merchants prefer to keep them separate to avoid showing pricing details to household members who might open the parcel unexpectedly, or to guests receiving a gift.
"I don't need an invoice for international B2C shipments." You do — but the document required is a commercial invoice, not a consumer-facing sales receipt. These overlap in content but the commercial invoice for customs has specific required fields (HS codes, country of origin, declared value) that a standard Shopify order receipt does not necessarily include. Packrooster generates commercial invoices automatically for international shipments with the correct fields populated from the order data.
"The shipping label is just a sticker — the carrier figures out the rest." The shipping label is the only information the carrier has. The routing barcodes on the label are what automated sorting systems use to direct the parcel through the network. A label with a corrupted barcode, wrong service code, or incorrect postalcode will not reach the right destination regardless of what the carrier knows about the sender's intentions.
"I only need one document per shipment." You typically need all three. The packing slip goes inside, the shipping label goes outside, and the commercial invoice either travels with the parcel (in a clear document pouch for international shipments) or is transmitted electronically. Each serves a different function and the absence of any one of them creates a specific problem at a specific point in the shipment's journey.
How this connects to your Shopify store
Packrooster generates shipping labels for every carrier connected to your Shopify store — pulling the delivery address, service selection, and parcel details from the Shopify order to produce the correct carrier-formatted label automatically.
For international shipments, Packrooster generates the commercial invoice as part of the label creation process — populated with the product descriptions, declared values, HS codes, and country of origin data from your Shopify products and order. Where carriers support electronic customs submission (paperless trade), Packrooster transmits the commercial invoice data electronically so you do not need to print and physically attach it to every international parcel.
Packing slips are generated by Shopify natively as part of the order management workflow, and can be customized with your branding, returns instructions, and any inserts you want to include. For merchants using Packrooster's scan and ship workflow, the packing slip barcode is what the operative scans to pull up the order and trigger label generation — making the packing slip both a customer-facing document and an operational tool in the same fulfillment cycle.
For merchants who want more control over the design and content of their packing slips — custom layouts, branded inserts, picking list format — Approosters' companion app Printrooster handles packing slip and order document printing with extensive customization options.
Learn more about Packrooster →
Frequently asked questions
Do I always need to include a packing slip in the parcel? There is no legal requirement to include a packing slip for domestic B2C shipments in most markets. However, it is strongly recommended — it gives the customer a clear reference for their order, simplifies returns, and is a brand touchpoint. For B2B shipments and for markets where VAT invoices are legally required to be provided to the buyer (including most EU B2B transactions), a document showing the transaction details is required.
What is the difference between a commercial invoice and a customs invoice? They are the same thing. "Customs invoice" is an informal term for the commercial invoice submitted to customs authorities for an international shipment. The document itself is a standard commercial invoice — the same one you would issue to a B2B customer — with the addition of the HS codes, country of origin, and other fields required for customs assessment.
Can I use one document that serves as both packing slip and commercial invoice? Yes — a combined packing slip and commercial invoice is a common format for international B2C shipments, particularly for lower-volume merchants. It lists the order contents with descriptions, quantities, and values, satisfying both the customer's need for a contents list and the customs authority's need for a declared value and goods description. The trade-off is that prices are visible to anyone opening the parcel — which may not be desirable for gift shipments. Many merchants offer a gift option that suppresses the price information from the packing slip for personal shipments.
How long should I retain commercial invoices for customs purposes? Most EU customs authorities require commercial invoice records to be retained for at least five years. UK customs requires a minimum of four years. For VAT purposes, records generally need to be kept for at least six years in the UK and five to ten years across EU member states depending on the country. Packrooster retains digital records of customs documentation generated through its system, supplementing your own record-keeping.
What happens if my commercial invoice and CN23 show different values? Discrepancies between the declared value on the commercial invoice and the CN23 are a flag for customs authorities. Both documents should show the same value for the goods — the actual transaction price. If they differ, customs may hold the shipment and request clarification. Packrooster generates both the commercial invoice and the CN23 from the same Shopify order data, which ensures consistency between the two documents by default.
