110 ILCS 520/15
This Section applies only to those students who first enroll after the 2003-2004 academic year. For 4 continuous academic years following initial enrollment (or for undergraduate programs that require more than 4 years to complete, for the normal time to complete the program, as determined by the University), the tuition charged an undergraduate student who is an Illinois resident shall not exceed the amount that the student was charged at the time he or she first enrolled in the University. However, if the student changes majors during this time period, the tuition charged the student shall equal the amount the student would have been charged had he or she been admitted to the changed major when he or she first enrolled. An undergraduate student who is an Illinois resident and who has for 4 continuous academic years been charged no more than the tuition amount that he or she was charged at the time he or she first enrolled in the University shall be charged tuition not to exceed the amount the University charged students who first enrolled in the University for the academic year following the academic year the student first enrolled in the University for a maximum of 2 additional continuous academic years.
110 ILCS 520/15