Commercial invoice for customs: what it must contain and how it differs from a proforma

MONDAY, 2 NOVEMBER 2026

The items that cannot be missing, how the invoice price becomes the customs value, the exchange rate set on the penultimate Wednesday of the month, when a proforma is used and a worked example with duty and VAT.

A commercial invoice for customs is the document in which the foreign supplier requests payment for the goods and, at the same time, the document customs starts from to calculate import duty and VAT. If it is incomplete or does not match the other documents, clearance stops.

In trade with China and Asia the English name, commercial invoice, is almost always used, even in Italy. This guide explains what it must contain, how its price becomes the customs value, which exchange rate applies when it is in dollars, how it differs from a proforma invoice and which mistakes are worth catching before the goods leave.

Commercial invoice: what it is and what it is for

The seller issues it when the goods are ready to ship and sends it to the buyer with the other documents: the packing list, which describes the packages, and the international transport document, such as the bill of lading. For an importer it does three jobs. It proves the agreed price and terms of sale. It is the reference for paying the supplier, even when payment goes through a bank. And it is the basis of the customs declaration.

In the import declaration the invoice is not just attached as a copy: it is referenced with a document code. In the Italian Customs Agency's code table the commercial invoice is code N380, the proforma invoice code N325, while code N935 identifies the invoice on the basis of which the customs value of the goods is declared. That is the document the officer compares with the declared value.

What a commercial invoice must contain

For goods imported into the European Union there is no single format required by law: every supplier uses its own. The information the customs broker needs is always the same, though, and it is worth requesting it in writing in the purchase order:

• References: invoice number and date, and the number of the order or contract it relates to.
• Parties: full name and address of seller and buyer, with the importer's EORI number.
• Goods: precise description of each item, commodity code, quantity, unit of measure and country of origin.
• Values: unit price, line total, discounts, grand total and currency.
• Terms: Incoterm with the place of delivery, payment terms, number of packages and net and gross weights.

The Incoterm deserves particular attention. FOB Shanghai and CIF Genoa do not only say who pays for transport: they change which costs are already included in the invoice price and which must be added to reach the customs value. Without the Incoterm the duty calculation cannot be closed.

Commercial invoice for customs: the customs value

The Union Customs Code, Regulation (EU) No 952/2013, sets the transaction value as the main method: the price actually paid or payable for the goods when sold for export to the Union. The invoice price is therefore the starting point, not always the end point.

Article 71 of the Code lists the elements to be added when they are not already included in the price. They include the cost of transport and insurance of the imported goods and the loading and handling charges associated with that transport, up to the place where the goods are brought into the customs territory of the Union. An FOB invoice therefore requires adding ocean freight and insurance to the European port; a CIF invoice already contains them. The duty calculation itself has its own rules, which we do not repeat here: what matters is that the invoice carries every element needed to do it.

Invoice in dollars: which exchange rate applies

Most Chinese invoices are in US dollars, sometimes in yuan. The customs value, however, must be expressed in euros, and the rate is neither the one on the payment date nor the one the bank applies. Article 146 of Implementing Regulation (EU) 2015/2447 states that, for euro countries, the rate published by the European Central Bank on the penultimate Wednesday of each month is used, and that this rate applies for the whole following month, from its first day.

For importers this has a practical consequence: for a declaration lodged in December the rate is already known at the end of November, and the duty in euros can be estimated precisely before the ship arrives. The difference between the customs rate and the rate actually paid to the supplier remains an accounting matter, not a customs one.

Commercial invoice or proforma: the difference

The proforma invoice has two different uses, and that is where the confusion comes from. In the first it is a formal quotation: the supplier sends it before the order or before the deposit, with prices and terms, and the buyer uses it to approve the expense or arrange a payment. It is not a final request for payment and does not replace the commercial invoice that comes with the goods.

In the second use it accompanies goods that are not paid for: free samples, warranty replacements, promotional material, returns. In this case the proforma is the document on which the goods are declared to customs, but the value cannot be zero. Carriers and operating guides agree: state the real value or the production cost of the sample, with wording such as «No charge. Value for customs purposes only». A sample declared at zero value is the quickest way to attract an inspection.

Origin on the invoice

The country of origin written on the invoice is not a detail. For many Chinese products it decides whether an anti-dumping duty applies and at what rate, and it matters for labelling rules. For goods covered by a trade agreement, on the other hand, the invoice can itself become the proof of preferential origin.

One example is the agreement between the European Union and Vietnam. For consignments whose originating products do not exceed EUR 6,000, any Vietnamese exporter can write an origin declaration on a commercial document, such as the invoice, signed by the exporter. Above EUR 6,000, an EUR.1 certificate is required for import into the Union. Anyone buying in Vietnam to pay the reduced duty should therefore request the invoice declaration for small lots and the certificate for larger ones, and check the wording before shipment.

Practical example with figures

An example with hypothetical figures, to see how the invoice becomes a tax base. A company imports 2,000 desk lamps from China at 12 dollars each, FOB Shanghai: the commercial invoice shows 24,000 dollars. Ocean freight to Genoa costs 2,100 dollars and insurance 60 dollars. The customs value is therefore 24,000 + 2,100 + 60 = 26,160 dollars.

If the customs rate for the month were 1.16 dollars per euro, the customs value would be EUR 22,551.72. With a hypothetical 4% duty, the duty payable would be EUR 902.07. Italian import VAT at 22% is calculated on the customs value plus duty, that is on EUR 23,453.79, and amounts to EUR 5,159.83, plus the ancillary costs to the destination in Italy that enter the VAT base. Had the invoice not shown the Incoterm, the broker would not have known whether to add the 2,160 dollars of freight and insurance: a mistake that would have reduced the customs value by more than 8%, with the difference to be paid if checked.

Common mistakes in the commercial invoice

The mistakes that stop or slow down clearance are almost always the same:

• Generic descriptions such as «parts» or «accessories», which make it impossible to classify the goods.
• Quantities or package counts that differ from the packing list and the bill of lading.
• A missing Incoterm, or one different from the contract, which makes the customs value uncertain.
• A value lower than the price actually paid, often proposed by the supplier to reduce duty.

The last point deserves a clear sentence: an undervalued invoice does not protect the importer. The transaction value is the price paid or payable, and the transfers to the supplier document it. In a post-clearance audit, the gap between invoice and payments becomes additional duty and VAT to settle, with penalties.

How long to keep the invoice

The invoice is not filed away after release. Article 51 of the Union Customs Code requires the importer to keep the documents and information of the declaration for at least three years, in a form accessible to the customs authorities; national law may set longer periods. This is the period in which customs can return to a declaration already closed, and the commercial invoice is the first document it asks for.

With La Merce the commercial invoice is checked before the goods leave China: description, commodity code, Incoterm and value are compared with the order and the packing list, so the document that reaches customs is one on which duty and VAT can be calculated without corrections.

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