According to the definition of the International Monetary Fund (IMF), a country's currency is classified as convertible if it is freely convertible under the current account. Because the freely convertible clauses are concentrated in Article 8 of the IMF Agreement, countries with freely convertible currencies are also called "Article 8 countries".

Specifically, the requirement of convertibility is contained in Article 8, paragraphs 2, 3 and 4, of the IMF Agreement, which reads as follows:

(1) Avoid restrictions on recurring payments or transfers. Without the consent of the International Monetary Fund, member countries may not impose exchange restrictions on international current payments and funds. (2) Discriminatory monetary measures or multiple exchange rate measures shall not be implemented. (3) payment of domestic currency held by foreign countries. Any member country has the obligation to buy back the balance of its own currency held by other member countries, as long as the exchange country can prove that this balance was obtained by the recent current exchange, or that this exchange was carried out to meet the needs of current exchange.