80 Ill. Adm. Code 1540.190
Lump Sum Salary Payments
Section 1540
Section 1540.190 Lump Sum
Salary Payments
a) Employee retirement contributions are not to be assessed
against certain lump sum salary payments as provided in the Act.
b) Compensation received for unused compensatory time shall be
applied to the pay period in which it was earned, rather than when it was
received.
c) Compensation received for back wages shall be applied to the
pay period in which it was earned, rather than when it was received.