2.2 upgrade
A payment that lets Tier 1 service before July 1, 1998 earn the 2.2% formula instead of the lower sliding scale.
These are the words you'll meet on your TRS Illinois Benefits Report and on these pages. To put them to work, try the TRS Illinois calculator, or start with Tier 1 or Tier 2 and the pension formula.
AAI
Annual increase in annuity, the yearly raise on your pension.
Annuitant
A member receiving a TRS Illinois retirement annuity. You become one when you receive your first payment.
APB
The Accelerated Pension Benefit, a one-time payment to inactive members in place of any pension.
Early Retirement Option (ERO)
A former program that let some Tier 1 members retire before 60 without the full cut. It expired July 1, 2016.
Final average salary (FAS)
The salary average the pension is based on (4 years for Tier 1, 8 for Tier 2).
Reciprocal service
Credit in another Illinois public system (IMRF, SURS, SERS, CTPF and others) that can count toward TRS Illinois eligibility. You need at least one year in each system.
Reversionary annuity
A smaller pension for you so a dependent beneficiary gets a monthly payment after you die.
Salary cap
The yearly limit on Tier 2 salary that counts toward the pension; for FY27 it is $129,192.26.
Service credit
One year for each school year with 170 paid days; fewer days earn a fraction (days / 170).
Standard annuity
The largest monthly pension, paid for your lifetime.
THIS Fund
The Teachers' Health Insurance Security Fund, which pays for TRIP. Active members pay 0.90% of pay into it.
Tier 1 / Tier 2
The two benefit levels. Tier 1 is for members who first contributed before Jan. 1, 2011 (or had reciprocal service before then); Tier 2 for everyone who started on or after that date.
TRIP / TRAIL
TRIP is the retiree health program; TRAIL is its Medicare Advantage plan for members with Medicare A and B.
Vested
Having enough service to qualify for a pension later, 5 years in Tier 1 and 10 in Tier 2.
No terms match. Try a shorter word.
Plain English, not the official wordingThese definitions put the TRS Illinois member guides into everyday words. They aren't TRS Illinois's official definitions, and they aren't legal or financial advice. TRS Illinois decides your benefit.
Source: TRS Tier 1 and Tier 2 Member Guides, September 2026, Tier 1 Guide pp. 1, 2, 8, 18, 19, 20, 21, 24; Tier 2 meeting slides 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 58, 60, 66; Tier 2 Guide pp. 1, 18, 19; TRIP Summary FY27 p. 2; TRS Illinois web page. Last reviewed .