Independent, source-linked pension research
Rules reviewed August 2026
Illinois teacher retirement system
Tier 1 and Tier 2 eligibility, the 2.2 formula, refunds, survivor benefits and post-retirement employment.
Complete topic cluster
01Membership tier
Illinois TRS Tier 1 vs Tier 2: the 2011 cutoff, retirement ages (55/60 vs 62/67), the 2.2% formula, the pensionable salary cap, and the COLA/AAI difference.
02Benefit formula
The Illinois TRS 2.2 formula is 2.2% x years of service x final average salary, capped at 75%. A worked example, the FAS rules, and the pre-1998 upgrade.
03Leaving employment
Understand the contributions returned, benefits forfeited and comparison vested members should make before applying.
04After retirement
Illinois TRS post-retirement work limits: 120 paid days or 600 paid hours a year, the affected-annuitant rule, and what suspends the pension.
05Disability
How Illinois TRS nonoccupational disability, occupational disability, and disability retirement annuity rules differ, with eligibility and payment checkpoints.
06Survivor benefits
How Illinois TRS beneficiary refunds and survivor benefits work, including dependent status, monthly eligibility, claim timing, and tier checks.
07Divorce
How an Illinois TRS QILDRO divides pension or refund payments, when a Calculation Order is needed, and which forms apply to the SSP.
08Retiree health
How the Illinois THIS Fund relates to TRIP retiree health coverage, who can enroll, and which Medicare, residence, and timing details matter.
09Service credit
How Illinois TRS converts unused uncompensated sick leave into service credit, the 340-day maximum and what employers must report at retirement.
010Service credit
How Illinois TRS calculates the Tier 1 2.2 upgrade for pre-July 1998 service, what the graduated formula does, and how later service can reduce cost.
011Benefit formula
How the Illinois TRS actuarial money-purchase benefit works for older Tier 1 members, who remains eligible, and how it compares with the formula annuity.
012Membership tier
How the Illinois TRS Tier 2 pensionable salary cap works in 2026–27, how it affects final average salary, and what to verify before retirement.
013COLA
Compare Illinois TRS Tier 1 and Tier 2 automatic annual increases, including start dates, compounding, CPI limits and the Tier 1 AAI option.
014Employer rules
How the current Illinois TRS 6% end-of-career salary increase rule can create employer pension costs and why it is not a teacher pay cap.
015Reciprocity
How Illinois TRS reciprocity can combine public-system service for eligibility, use final average salary, handle refunds and produce separate pension checks.
016Buyout
How the Illinois TRS Accelerated Pension Benefit buyout works for eligible inactive Tier 1 and Tier 2 members, including the 2028 extension.
017Supplemental savings
How the Illinois TRS SSP 457(b) supplements the pension, who can participate, how 3% automatic enrollment works and what to review before saving.
018Membership tier
What Illinois TRS Tier 2 means if you started teaching on or after January 1, 2011: the age-67 retirement rule, the eight-year salary average, the capped pensionable salary, and the slower COLA.
019Benefit formula
Which parts of a teacher's pay are "creditable earnings" for Illinois TRS, what is excluded, and how the 6% end-of-career raise rule can leave your district with a bill when you retire.
020Benefit structure
What the Illinois TRS Supplemental Savings Plan is, how the automatic 3% enrollment works for newer teachers, the 2026 contribution limits, and how it fits alongside a Tier 1 or Tier 2 pension.
021Tiers
Tier assignment in Illinois TRS is set by law, based on your first contribution date — not a choice you or your employer can elect. Here's exactly what determines your tier, and what Tier 2 members can and can't do about it.
022Social Security
TRS-covered teaching in Illinois doesn't pay into Social Security, which historically triggered the WEP and GPO offsets. The Social Security Fairness Act repealed both. Here's what that means if you also worked Social Security-covered jobs.
023System basics
A big-picture entry point to Illinois TRS before you dive into tier comparisons or benefit formulas — who's covered, how it's funded, and the single most important date that determines your tier.
024Vesting
Tier 1 and Tier 2 members vest at different points in Illinois TRS. Here's the exact service requirement for each tier, and what a refund actually pays out if you leave before you get there.
025COLA
Illinois TRS Tier 1 generally receives a compounded 3% annual increase starting after age 61; Tier 2 receives up to 3% (half CPI when lower), without compounding, starting after age 67.
026Taxes
TRS benefits are fully taxable federally but completely exempt from Illinois state income tax — here's how that split actually works on your 1099-R and how to set your federal withholding.
027Eligibility
The exact age-and-service combinations TRS uses to decide whether you get a full annuity or a reduced one — Tier 1 and Tier 2 use completely different tables.
028Eligibility
The eligibility table tells you whether you can retire early. This walks through what the 6%-per-year reduction actually does to a real dollar figure, and for how long.
029Service credit
Out-of-state teaching, military service, private school time, even unpaid leaves — TRS lets you purchase several kinds of non-TRS service as creditable service. Here's what qualifies, the caps, and the cost formula.