We recommend that merchandise invoices include the following:
Weight, item description, number of pieces, origin-destination, value, terms of the client-vendor service contract, certificate of origin, and additional paperwork with any permits and/or authorizations required to move the goods or merchandise (Normas Oficiales Mexicanas, SAGARPA, SEMARNAT, etc.)
Article 36 of the Mexican Customs Law (Ley Aduanera) will define what is required by the Mexican government to import merchandise. The requirements for exporting are defined by the laws of the country of destination.