The Illinois General Assembly created the Teachers’ Retirement System of the State of Illinois (TRS or the System) in 1939 for the purpose of providing retirement annuities, and disability and survivor benefits for educators employed in public schools outside the city of Chicago.

The System's enabling legislation is in the Illinois Pension Code at 40 ILCS 5/16-101[3] TRS members fall into the following categories: active, inactive, annuitant, and beneficiary.

Persons employed in certain state agencies and statewide or national organizations related to education are also active TRS members.

Inactive members are no longer contributing to the System but have service credit that will entitle them to draw a benefit or refund when statutory eligibility requirements are met.

Changes from the “Tier I” pension law include raising the minimum eligibility to draw a retirement benefit to age 67 with 10 years of service, initiating a cap on the salaries used to calculate retirement benefits, and limiting cost-of-living annuity adjustments to the lesser of 3 percent or half of the annual increase in the Consumer Price Index, not compounded.