Ill. Admin. Code tit. 86, § 423.165
a) When the amount due is under $300, the following are guilty of a Class 4 felony:
A) fails to file a return;
b) When the amount due is $300 or more, the following are guilty of a Class 3 felony:
f) Any person who fails to keep books and records or fails to produce books and records for inspection, as required by Section 423.145, is liable to pay to the Department, for deposit in the Tax Compliance and Administration Fund, a penalty of:
h) A person commits the offense of tax evasion under the Law when he or she knowingly attempts in any manner to evade or defeat the Tax imposed on him or her or on any other person, or the payment of that Tax, and he or she commits an affirmative act in furtherance of the evasion.
1) As used in this Section, "affirmative act in furtherance of the evasion" means an act designed in whole or in part to:
2) Two or more acts of tax evasion may be charged as a single count in any indictment, information, or complaint and the amount of Tax deficiency may be aggregated for purposes of determining the amount of Tax that is attempted to be, or is, evaded and the period between the first and last acts may be alleged as the date of the offense.