In accordance with Article 2 of the Immigration Act, the functions and powers are based on the border control subject to the former Immigration Bureau and businesses related to immigration from the Council of the Overseas Chinese Affairs and the Department of Population under the Ministry of the Interior. The NIA also encompasses partial duties of the Foreign Affairs Division of the National Police Agency, the Foreign Affairs and Mainland Affairs Sections of the Police Bureaus nationwide, the Document Examination Brigades of the Aviation and Harbor Police Offices, and Special Police First, Fourth, and Fifth Headquarters.