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Montana TRS · Methods and sources

How we estimate Montana TRS pensions

Every number on the Montana pages comes from Montana Teachers' Retirement System (Montana TRS) fact sheets and web pages, its July 1, 2025 actuarial valuation and annual report, or Montana Code Annotated Title 19, Chapter 20. Here's what the calculator does, and what it leaves out.

This page explains the Montana TRS calculator. The rules it uses are in plain English on the formula, tiers and early retirement pages.

No member handbook Check with Montana TRS

Montana TRS's current site publishes no member handbook; the rules come from fact sheets, web pages, the valuation and statute.

Statute, fact sheets and web pages

What would settle it: A current Montana TRS Active Member Handbook, if one exists (ask Montana TRS).

So these pages cite Montana TRS fact sheets and web pages, its July 1, 2025 actuarial valuation, and the statute, MCA Title 19, Chapter 20. Where a fact sheet and the statute differ, we follow the statute: the fact sheets say Montana TRS law supersedes them.

  1. 1

    Find your tier

    Tier One if you became a member before July 1, 2013 and never withdrew; otherwise Tier Two. A Tier One member who withdrew and came back is Tier Two.

    MCA 19-20-101(33)-(34), 19-20-603(3)(d), (4); Montana TRS web page: Understand Your Benefits (Tier 1 and Tier 2 Membership); Withdrawing TRS Membership fact sheet (Apr. 10, 2026), p. 1
  2. 2

    Count your service

    The years you enter, plus one year for each year from today to your retirement date (none if you've stopped working). Benefits start on the first of a month.

    MCA 19-20-703(2), (5); Terminating Employment and Retiring fact sheet (July 1, 2023), pp. 1-2; Montana TRS web page: Benefit Payments
  3. 3

    Check eligibility

    Tier One: 60 with 5 years, or any age with 25 years; early from 50. Tier Two: 60 with 5, or 55 with 30; 1.85% at 60 with 30; early from 55. Age is whole years on the retirement date.

    MCA 19-20-101(33), 19-20-801(1), 19-20-802(1)(a), 19-20-804(1), 19-20-805(1)(a); Montana TRS web page: Understand Your Benefits (Tier 1 Service Retirement; Standard Benefit Calculation Formula); Actuarial Valuation (July 1, 2025), pp. 47-48, Appendix B; MCA 19-20-101(34), 19-20-801(2)-(3), 19-20-802(1)(b), 19-20-804, 19-20-805(1)(b); Montana TRS web page: Understand Your Benefits (Tier 2 Service Retirement; Tier 2 Professional Option); Actuarial Valuation (July 1, 2025), pp. 47-48, Appendix B; Montana TRS FY2025 ACFR, p. 19 (Summary of Benefits)
  4. 4

    Apply the formula

    Years × your AFC × 1/60, or × 1.85% for the Tier Two professional option, ÷ 12. We use the AFC you enter, plus any termination pay under the option you pick.

    MCA 19-20-804; 19-20-703(1); Montana TRS web page: Understand Your Benefits (Standard Benefit Calculation Formula; Tier 2 Professional Option); MCA 19-20-716; 19-20-101(32); Termination Pay fact sheet (Mar. 26, 2026), pp. 1-3
  5. 5

    Early retirement

    We compute how many years the reduction covers: the shorter of the years to 60 and the years to 25 (Tier One) or 30 (Tier Two) years of service. We show the amount before the reduction, because Montana TRS publishes no factors. We never guess a percent.

    MCA 19-20-802(3); Actuarial Valuation (July 1, 2025), p. 48, Appendix B (Early Retirement Benefits); Montana TRS FY2025 ACFR, p. 79, Exhibit 6
  6. 6

    Show the options

    The Normal Form in dollars. Options A, B, C and the 10- and 20-year period certain only in words, because Montana TRS publishes no factors.

    MCA 19-20-702; Montana TRS web pages: Retirement Prep, Benefit Payments

What the calculator doesn't cover

How we check the math

The calculator runs on a small engine that reads every rule from one data file, with a source for each. Montana TRS publishes no worked benefit examples, so automated tests check the rules themselves (tier dates, ages, the reduction period, the 110% cap, termination pay, the break and the earnings limit) and every example Montana TRS does print. The tests run every time the site is built.

How we check the math (Montana TRS)
Montana TRS exampleMontana TRS showsOur engine
Extra duty: daily rate on a $38,000 baseCalculating and Reporting Extra Duty Service Credit fact sheet (May 15, 2025), pp. 2-3$203.21$203.21Match
Extra duty: days for each stipendCalculating and Reporting Extra Duty Service Credit fact sheet (May 15, 2025), pp. 2-329.53 and 23.6229.53 and 23.62Match
Extra duty: hours for each stipendCalculating and Reporting Extra Duty Service Credit fact sheet (May 15, 2025), pp. 2-3206.71 and 165.34206.71 and 165.34Match
Break in service: last day June 12, 2024, start September 1, 2024Terminating Employment and Retiring fact sheet (July 1, 2023), p. 3too soontoo soonMatch
Required beginning date: born February 1, 1949, stopped 2023Required Minimum Distributions (Oct. 11, 2024), p. 1, Example 1 fact sheetApril 1, 2024April 1, 2024Match
Required beginning date: born February 1, 1951, stopped 2026Required Minimum Distributions (Oct. 11, 2024), p. 1, Example 2 fact sheetApril 1, 2027April 1, 2027Match

Our own examples

These are our engine's results on Montana TRS's rules, not Montana TRS figures.

Things to check with Montana TRS

The sources don't settle these points. Each is labeled "Check with Montana TRS" where it shows up on the site.

Check with Montana TRS

Early-retirement reduction factors. MCA 19-20-802(3) requires actuarially equivalent factors from the latest valuation; no source publishes them. The valuation describes only the reduction period (lesser of years to 60 or years to 25/30 of service).

Unreduced amount shown, reduction period computed, reduced amount left blank

What would settle it: Montana TRS's current factor table or an Estimate of Benefits for an early retiree.

Check with Montana TRS

Payment-option factors. Options A, B, C and the period-certain options are actuarial equivalents of the Normal Form (MCA 19-20-702); no factors are published.

Only the Normal Form has a dollar amount

What would settle it: A Montana TRS Estimate of Benefits showing all six allowances, or a factor table.

Check with Montana TRS

Meaning of 'creditable service in 25 [30] or more years'. The statute and web page can be read as counting fiscal years with any credited service (part-time included), rather than 25 (30) full years of service.

Optional input yearsWithService (fiscal years with any credited service); defaults to serviceYears

What would settle it: Montana TRS's written interpretation of MCA 19-20-801(1)(b) and (2)(b), or an ARM 2.44 rule.

Check with Montana TRS

How age is counted. No source says whether eligibility age is attained on the birthday or the first of the next month; benefits start the first of a month (MCA 19-20-703).

Completed years of age on the retirement date

What would settle it: A Montana TRS estimate for a member born mid-month, or a written rule.

Check with Montana TRS

Mechanics of the 110% cap. MCA 19-20-805(5) caps each AFC year at 110% of the 'next prior year of service reported' and adds the excess like termination pay Option 2; the sources don't say whether the base is the reported or the capped prior year, or show an example.

Base = reported prior-year earnings; excess / total service added to AFC

What would settle it: Montana TRS's 'Ready, Set, Retire!' illustration of the 110% cap, or an EOB showing excess earnings.

Check with Montana TRS

IRC § 401(a)(17) dollar limit. MCA 19-20-715 applies the IRS limit to members who joined on or after July 1, 1996 but no source prints the dollar amount.

No cap applied; a note is shown

What would settle it: The current IRS limit as Montana TRS applies it.

Check with Montana TRS

Break in service after June 30, 2029. The temporary 120-day rule terminates June 30, 2029; the version effective July 1, 2029 says 150 days for terminations on or after Jan. 1, 2014, without saying how it treats people who terminated while the 120-day rule was in force.

120 days for terminations Jan. 1, 2024 - June 30, 2029; 150 days otherwise

What would settle it: Montana TRS guidance, or 2027/2029 legislation extending the rule.

Check with Montana TRS

Earnings limit after June 30, 2027. The 49% limit sunsets June 30, 2027 and the statute then reverts to one-third, unless the 2027 Legislature acts (2023 Legislative Summary p. 1 expects a review in the 2027 session).

49% for fiscal years through June 30, 2027; one-third afterwards

What would settle it: 2027 legislation or a Montana TRS notice.

Check with Montana TRS

Median AFC for the earnings limit. The fact sheet says the median AFC is posted on the Montana TRS website; we didn't find it on the pages saved.

Caller supplies it; otherwise the member's own AFC is used

What would settle it: The current median AFC figure from Montana TRS.

Check with Montana TRS

Options D and E. Mentioned on web pages and the FLO fact sheet but not in MCA 19-20-702.

Six allowances from the statute

What would settle it: Montana TRS confirming whether D and E are legacy options for older retirees.

Check with Montana TRS

Social Security coverage. Sources say most members get Social Security and FICA is withheld from termination pay, but none states the coverage arrangement directly.

Quote the sources; 'Check with Montana TRS'

What would settle it: Montana's Section 218 agreement summary or a Montana TRS statement.

Check with Montana TRS

Montana 65+ subtraction after 2024. The DOR page gives $5,500 ($11,000 joint) for tax year 2024 and says it is inflation-adjusted from 2025, without the new amount.

$5,500 / $11,000 labelled tax year 2024

What would settle it: Montana DOR Form 2 instructions for 2025 or 2026.

Administrative rules (ARM Title 2, Chapter 44) Check with Montana TRS

Board rules on creditable service, GABA and reemployment were not fetched (rules.mt.gov is a JavaScript app).

Statute and fact sheets only

What would settle it: ARM 2.44 text from rules.mt.gov.

Where sources disagreed

Sources

We cite the page printed on each fact sheet and report, and the section number in the Montana Code Annotated. Last reviewed Nov. 12, 2026.

Found a mistake?Email [email protected] with the page, what you entered, and what Montana TRS told you. We fix confirmed errors and note the change.
The official numbersOnly Montana TRS can tell you your actual benefit. Ask Montana TRS for an Estimate of Benefits: 406-444-3134, toll-free 866-600-4045.

Source: Montana TRS: Understand Your Benefits (web page) and fact sheets, Fetched Nov. 12, 2026; fact sheets revised 2019-2026, fact sheets: Calculating and Reporting Extra Duty Service Credit pp. 2-3; Required Minimum Distributions (Oct. 11, 2024), p. 1, Example 1; Required Minimum Distributions (Oct. 11, 2024), p. 1, Example 2; Terminating Employment and Retiring pp. 1-2, 3; Termination Pay pp. 1-3; Withdrawing TRS Membership p. 1. Also: Montana TRS web pages: Benefit Payments, Retirement Prep; Actuarial Valuation (July 1, 2025); FY2025 Annual Comprehensive Financial Report; MCA §§ 19-20-101, 19-20-603, 19-20-702, 19-20-703, 19-20-716, 19-20-801, 19-20-802, 19-20-804, 19-20-805. Last reviewed .