Your tier sets your retirement ages, your salary average and your yearly increase. The calculator picks your tier from your first paid day.
Tier 1 vs Tier 2, side by side
| Tier 1 | Tier 2 | |
|---|---|---|
| WhoTier 1 Guide p. 1, Foreword | First paid to TRS Illinois before Jan. 1, 2011 (or had reciprocal service before then) | First paid on or after Jan. 1, 2011, with no earlier reciprocal service |
| Vested afterTRS Illinois Tier 2 slides, slide 60, Benefit Comparison (Minimum Vesting Period: 10 years) | 5 years | 10 years |
| Full (unreduced) pensionTier 1 Guide p. 17, Ch. 9 Retirement Benefits (age and service table); Tier 2 Guide p. 18, Eligibility; Reduced retirement annuity | 62 with 5 yrs · 60 with 10 yrs · 55 with 35 yrs | 67 with 10 yrs |
| Earliest, reducedTier 1 Guide p. 18, Reduced retirement annuity; Tier 2 Guide p. 18, Reduced retirement annuity | 55 with 20 yrs, cut 6% a year under 60 | 62 with 10 yrs, cut 6% a year under 67 |
| FormulaTier 2 Guide p. 18, Capping average salary (2.2% x FAS x years); TRS Illinois Tier 2 slides, slide 14, Formula Factor | 2.2% × years × salary average | 2.2% × years × salary average |
| Salary averageTier 1 Guide p. 17, Average salary; Tier 2 Guide p. 18, Average salary | Best 4 years in a row of the last 10 | Best 8 years in a row of the last 10 |
| Pay capTier 2 Guide p. 18, Capping average salary; TRS Illinois Tier 2 slides, slides 15 and 60 | None from TRS Illinois | $129,192.26 in FY27, rises with inflation |
| Most you can getTier 1 Guide p. 17-18, Annuity calculation; Maximum retirement benefit; Tier 2 Guide p. 18, Maximum retirement benefit | 75% of your average | 75% of your average |
| Yearly increaseTier 1 Guide p. 23, Annual increases in annuity; Tier 2 Guide p. 22, Annual increases in annuity | 3%, compounded, from the Jan. 1 after age 61 (and 1 year retired) | Lesser of 3% or half of inflation, not compounded, from age 67 |
What the difference is worth
Take the TRS Illinois example member: 30 years of service and an $85,000 salary average. Both tiers use the same 2.2% formula, so the full pension is the same: $56,100 a year ($4,675 a month). TRS Illinois Tier 2 slides, slide 17
| Retire at | Tier 1 | Tier 2 |
|---|---|---|
| 60 | $4,675/mo, full pension | Not eligible yet (earliest is 62) |
| 62 | $4,675/mo, full pension | $3,272/mo, cut 30% for life |
| 67 | $4,675/mo, full pension | $4,675/mo, full pension |
The Tier 2 rows are TRS Illinois's own examples TRS Illinois Tier 2 slides, slide 17; TRS Illinois Tier 2 slides, slide 18. The Tier 1 rows are our illustration from the Tier 1 rules. They leave out yearly increases, which also differ by tier. See Yearly increases.
What the guides say
- If you first contributed to TRS Illinois before Jan. 1, 2011, you are in Tier 1. If your first contribution was on or after that date, you are in Tier 2.Tier 1 Guide p. 1, Foreword; Tier 2 Guide p. 1, Foreword
- Your first contribution is your first day of paid service in a TRS-covered position.Tier 1 Guide p. 1, Foreword
- If you started with TRS Illinois in 2011 or later but already had service in a reciprocal Illinois pension system (such as SURS, IMRF, SERS or CTPF) before Jan. 1, 2011, you are Tier 1.Tier 1 Guide p. 1, Foreword; Tier 2 Guide p. 1, Foreword
- The big Tier 2 differences: full retirement at 67 instead of 60, 10 years to vest instead of 5, an 8-year salary average instead of 4, a cap on pensionable salary, and smaller, non-compounded yearly increases.TRS Illinois Tier 2 slides, slide 60, Benefit Comparison
- Both tiers pay 9% of gross earnings to TRS Illinois: 7.5% for the pension, 0.5% for annual increases and 1% for survivor benefits.Tier 1 Guide p. 7; Tier 2 Guide p. 8, Member contributions
Questions
What decides my tier?
The date you first contributed to TRS Illinois, which is your first day of paid service in a TRS Illinois-covered job. Before Jan. 1, 2011 is Tier 1. On or after is Tier 2.
I started in 2012 but worked for IMRF before 2011. Which tier am I?
Tier 1. Service in a reciprocal Illinois system before Jan. 1, 2011 keeps you in Tier 1 even if your TRS Illinois service started later.
Can I switch tiers?
The member guides don't describe any way to switch. Your tier follows your first contribution date.
Source: TRS Tier 1 and Tier 2 Member Guides, September 2026, Tier 1 Guide pp. 1, 7; Tier 2 Guide pp. 1, 8; Tier 2 meeting slides 5, 17, 18, 60. Last reviewed .