Any shipment of goods or documents outside the EU is subject to declaration in accordance with the applicable customs regulations. This means that a commercial invoice or a pro forma invoice must accompany the shipment.
Regardless of whether it is a commercial invoice or pro forma invoice - the document names the shipper and consignee of the goods and contains a complete description of all the contents as well as information on their value. The signatory is the shipper and in addition to the original, 3 copies must accompany the parcel.
You can use this online form to create your commercial invoice or proforma invoice and print it on your company's letterhead.