UNMCII1 CII CrossIndustryInvoice 1.0 The cross industry invoice is an electronic document exchanged between trading partners with a prime function as a request for payment. It is an important accounting document and has potential legal implications for sender and receiver. It is also used in the European Union as the key document for VAT declaration and reclamation, for statistics declaration in respect of intra community trade, and to support export and import declaration in respect of trade with countries outside the European community.