A certificate of origin is an official document certifying the country where goods were produced, manufactured or substantially transformed. Two fundamental types exist: 1) Non-preferential certificate of origin — certifies 'made in' without granting tariff benefits. Issued by the Chamber of Commerce of the exporting country. Required when the destination country needs it for statistical, trade control or commercial policy reasons (antidumping, quotas, embargoes); 2) Preferential certificate of origin (EUR.1, EUR-MED, Form A, invoice declaration) — enables reduced or zero duties under a free trade agreement, requiring proof that goods meet the agreement's origin rules (sufficient processing, tariff heading change, minimum value added). When needed: the importer or destination country requires it for customs clearance; the letter of credit (L/C) lists it as mandatory; preferential duties are sought; antidumping measures or origin-based restrictions exist. In Switzerland, the cantonal Chamber of Commerce issues non-preferential certificates. For preferential origin, BAZG issues EUR.1 and authorises exporters for invoice declarations.