To qualify for a “G” visa you must be entering the United States in pursuance of official duties to an international organisation designated by Executive Order pursuant to various treaties or under the International Organizations Immunities Act (IOIA) of December 29, 1945. (e.g. United Nations, World Bank, International Monetary Fund)
G-1 Members of a permanent mission of a recognized government to an international organization.
G-2 Representatives of a recognized government traveling to the United States temporarily to attend meetings of a designated international organization.
G-3 Representatives of non-recognized or non-member governments.
G-4 Visas are issued to individual personnel who are proceeding to the United States to take up an appointment at a designated international organization.
G-1, G-2, and G-3 visa applications must be accompanied by a Note Verbale from the applicant’s national government. G-4 visa applications must be accompanied by an official request from the appropriate international organization (the G-4 note must be sent directly by cable to the consular section from the int. org.)