It differs according to students' nationalities and other information. D-4 visas can be extended at the immigration office with the certificate of enrollment you can issue at the office of CKLC. It can be extended until the date that you have registered for our center. C-3 visa extension varies according to nationalities, so students must contact the immigration office for accurate information. Documents you need are admission letter, certificate of enrollment, certificate of bank balance, reference letter, and reciept of payment.