IL HB4321

Amends Section 15-186.1 of the Illinois Pension Code to clarify procedures for handling benefit calculation mistakes and overpayments by pension systems.

Requires pension systems to recalculate and correct benefits set at incorrect amounts as soon as practicable after discovery, with lump sum payments plus interest for underpayments.

Establishes a 3-year protection period: if a benefit was overpaid due to system error and the error went undiscovered for 3 years or longer and was not caused by incorrect or omitted information from the member, the recipient is not required to repay the excess amounts.

Authorizes pension systems to recover all other overpayments regardless of discovery date, including those occurring before the act's effective date, plus interest, either directly or by deducting from remaining benefits.

Takes effect upon becoming law.