Ill. Admin. Code tit. 23 § 1.460
Each local board of education with a high school shall adopt a policy which defines the board's position with reference to the awarding of high school credit on the basis of local examinations to pupils who have achieved the necessary proficiencies through independent study, either with or without private tutoring, or for work taken in or from another institution. Plans for earning credit outside of regular classes should be approved in advance by the local high school principal according to established policy. The pupil's permanent record should show how the credit was earned. The examination papers upon which such credit is validated should be kept in the school file for three years as evidence for recognition and accreditation agencies.
Ill. Admin. Code tit. 23, § 1.460