Illinois Statutes Chapter 35. Revenue § 735/3-4.5. Collection penalty

(a) If any liability (including any liability for penalties or interest imposed under this Act) owed by a taxpayer with respect to any return due on or after July 1, 2003, is not paid in full prior to the date specified in subsection (b) of this Section, a collection penalty shall be imposed on the taxpayer. The penalty shall be deemed assessed as of the date specified in subsection (b) of this Section and shall be considered additional State tax of the taxpayer imposed under the law under which the tax being collected was imposed.

(b) The penalty under subsection (a) of this Section shall be imposed if full payment is not received prior to the 31st day after a notice and demand, a notice of additional tax due or a request for payment of a final liability is issued by the Department.

(c) The penalty imposed under this Section shall be: