IELTS: Minimum required overall band score of 6.0. TOEFL: 71 on an Internet-based test, 527 on a paper-based test. The ACT or SAT is required for international freshmen applicants from U.S. high schools. High School Diploma: You must have graduated by the time you start at NIU in order to be admitted. Grades: You must have passing grades equivalent to a U.S. C plus average on all transcripts and/or exam scores.