How we estimate TRS Illinois pensions

We built these pages from TRS Illinois's own member guides and slides. We could not download the Illinois Pension Code itself, so no rule has been checked against the law yet.

What we use: We follow the September 2026 member guides. The guides say the law wins if they ever disagree.

The Tier 1 guide says the early cut is half a percent per month. TRS Illinois's slides say age is counted to three decimal places. Both give the same cut at whole months; they can differ by a few hundredths of a percent in between.

What we use: We count whole months plus the fraction of the current month, then take 6% per year.

If you never paid the 2.2 upgrade, your years before July 1998 use a lower, stepped rate. The guide doesn't say whether those older years fill the first steps of the schedule.

What we use: We treat your pre-July 1998 years as your first years (1.67% for years 1-10, and so on), and later years at 2.2%.

Tier 2 members with under 5 years can get a one-time payment at 65, and members with 10 years get a pension. The guide doesn't say what 5 to 9 years gets.

What we use: We show 'not eligible' for 5 to 9 years in Tier 2 and point you to TRS Illinois.

Tier 2 pay is capped, and the cap rises each year with inflation. We only have the FY27 cap ($129,192.26), not the earlier years' caps.

What we use: We apply the FY27 cap to every year. That can overstate a high earner's average a little.

Only the Tier 1 guide says 74.6% rounds up to 75%. But TRS Illinois's Tier 2 slides say 34 years = 75%, which only works with the same round-up.

What we use: We round 74.6% or more up to 75% in both tiers.

If a Tier 1 member takes the AAI buyout, the 1.5% raises start 'at a later date'. The guide doesn't say when.

What we use: We don't guess the date, so we don't project AAI-buyout raises. Ask TRS Illinois for the start date.

The guide doesn't say how the AAI buyout payment is worked out.

What we use: We don't estimate the payment. TRS Illinois sends an estimate when you ask at retirement.

The APB buyout is 60% of the present value of your pension, but TRS Illinois doesn't publish the interest and life-expectancy figures it uses.

What we use: We don't estimate a dollar amount. TRS Illinois mails eligible members an offer.

A reversionary annuity lowers your check to pay a survivor, but the guides don't say by how much.

What we use: We show the standard annuity only. Ask TRS Illinois for a reversionary estimate.

The Tier 2 guide says member raises use the CPI 'as of the preceding September', but survivor raises use the 'preceding calendar year'.

What we use: We let you enter an inflation figure and apply the half-of-CPI, 3%-cap rule to it.

The guide says your contributions earn 6% interest a year, but a refund is paid 'without interest'.

What we use: We show the refund as the guide states it: 7% or 8% of your earnings, no interest.

Tier 1's first raise covers all the years since you retired (years x 3%). The guide doesn't say how part-years are counted.

What we use: We count complete months, so 18 months is 1.5 years, a 4.5% first raise.

Two TRS Illinois documents show different Medicare (TRAIL) premiums: $7.72 on the FY27 slides and $8.11 from Jan. 1, 2027.

What we use: We show each with its date.