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HomeMedicare SupplementMontanaMedigap in Montana for 2027: 23 Insurers and the Plans They Sell

Medicare Supplement

Medigap in Montana for 2027: 23 Insurers and the Plans They Sell

BILLINGS, Mont. — As Montanans weigh their Medicare choices for the coming year, Medicare Supplement coverage — commonly called Medigap — remains one of the central pieces of the puzzle. A search on Medicare.gov's Medigap policy finder for ZIP code 59101 returns 23 insurers selling standardized plans in the state, with plan letters ranging from A through N.

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Key takeaways

  • Medicare.gov's Medigap policy search for ZIP 59101 lists 23 insurers in Montana, offering some combination of Plans A, B, C, D, F, F-HD, G, G-HD, K, L, and N.
  • The strongest window to buy Medigap without medical underwriting is the six-month Medigap Open Enrollment Period that begins when you are 65 or older and enrolled in Part B.
  • 12 Medicare Advantage plans offered in Montana in 2026 will not be offered anywhere in the state in 2027, and members of a non-returning plan get a federal guaranteed-issue right to buy certain Medigap plans.
  • Medigap does not include prescription drug coverage, so a stand-alone Part D plan is chosen separately during Annual Enrollment, October 15 – December 7, 2026, for coverage effective January 1, 2027.
Happy senior couple at home — illustrating this Medicare guideMedicare SupplementMontana
Photo: Polifoto Image by Polifoto on Pixabay
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By MyMedicarePlans Editorial Desk · Medicare Education✓ Verified Team
Published ·9 min read·✓ Reviewed
Key facts: Medicare in Montana
FactFigureSource
Part B standard monthly premium (2026)$202.90Medicare.gov
Part D out-of-pocket cap (2026)$2,100CMS
Part D out-of-pocket cap (2027)$2,400CMS
Annual Enrollment Period (for 2027 coverage)October 15 – December 7, 2026Medicare.gov

Area counts are for the county as a whole and are not a recommendation of any plan. Program figures are set nationally.

What is Medigap and how is it different from Medicare Advantage in Montana?

Medigap is private insurance that works alongside Original Medicare (Part A and Part B) to help pay some of the out-of-pocket costs Medicare leaves behind, such as coinsurance. It is not Medicare Advantage. Medicare Advantage (Part C) replaces how you get your Part A and Part B benefits by routing them through a private plan, often with its own network and its own rules. With Medigap, you keep Original Medicare and add a supplement; with Medicare Advantage, you get your Medicare through the plan itself. You cannot have both at the same time.

Medigap plans are standardized by federal letter, which means Plan G from one company covers the same federally defined items as Plan G from another company. What differs between companies is price, service, and underwriting practices — details to confirm directly with each insurer or on Medicare.gov.

Which insurers sell Medigap in Montana, and which plan letters do they offer?

Medicare.gov's Medigap policy search for ZIP code 59101 lists 23 insurers. What any one person is offered can vary by ZIP code and by age, sex, and tobacco use.

The insurers and the plan letters shown for each are:

Across the state's listings, the plan letters sold by at least one listed insurer are A, B, C, D, F, F-HD, G, G-HD, K, L, and N. Plans C and F are closed to people who became newly eligible for Medicare on or after January 1, 2020.

What is the six-month Medigap Open Enrollment Period in Montana and why does it matter?

The Medigap Open Enrollment Period is a one-time, six-month window that begins the month you are both 65 or older and enrolled in Medicare Part B. During that window, an insurer in Montana must sell you any Medigap policy it offers, cannot charge you more because of your health history, and cannot make you wait for coverage of pre-existing conditions beyond the limits federal rules allow.

Outside that window, insurers in most situations may use medical underwriting — meaning they can decline you or charge more based on health — unless a separate guaranteed-issue right applies. That is why the six-month window matters: it is the broadest, cleanest shot most people get at any Medigap plan on the shelf.

What happens if my Medicare Advantage plan is leaving Montana for 2027?

According to the CMS Landscape files, 12 Medicare Advantage plans offered in Montana in 2026 will not be offered anywhere in the state in 2027. If you are enrolled in one of those non-returning plans, federal rules give you a guaranteed-issue right to buy certain Medigap plans, which means an insurer must sell you one of the specified policies without medical underwriting during a limited window.

Guaranteed-issue rights also apply in several other situations, such as losing certain kinds of coverage through no fault of your own. The specific plans available and timing rules are described on Medicare.gov.

Does Medigap cover prescriptions in Montana, or do I need a separate Part D plan?

Medigap sold today does not include prescription drug coverage, so a stand-alone Medicare Part D plan is chosen separately. For 2027, the Part D out-of-pocket cap is $2,400 (up from $2,100 in 2026), the maximum allowable Part D deductible is $700, and the national base beneficiary premium used in the late-enrollment penalty calculation is $41.33. Actual plan premiums are set plan by plan.

You can add or change a Part D plan during Annual Enrollment, October 15 – December 7, 2026, for coverage that begins January 1, 2027.

How should Montanans compare Medigap policies?

Because the benefits inside each federally standardized letter are the same from one insurer to the next, comparison usually comes down to price, how a company raises prices over time, customer service, and underwriting rules outside the open enrollment window. Confirm the current list of insurers and plan letters for your own ZIP code on Medicare.gov's Medigap policy search, and request specifics in writing from any insurer you are seriously considering.

Where can Montanans get free help with Medicare questions?

Medicare.gov has free comparison tools for Medigap, Part D, and Medicare Advantage, and 1-800-MEDICARE (TTY 1-877-486-2048) is staffed 24 hours a day, seven days a week. The Social Security Administration announced a 3.6 percent cost-of-living adjustment on October 14, 2026 for benefits payable beginning January 2027, which may affect household budgeting as you compare plan costs.

By the numbers

Medicare Part B premium, 2006–2026

The standard monthly Part B premium has climbed from $88.50 in 2006 to $202.90 in 2026. Hover any point for that year’s premium.

$0$50$100$150$200200820122016202020242026

Source: CMS. Standard premium shown; in some hold-harmless years many existing enrollees paid less. Confirm at Medicare.gov.

Key dates

Medicare enrollment periods at a glance

  • Around your 65thInitial Enrollment PeriodA 7-month window around the month you turn 65 — your first chance to sign up.
  • October 15 – December 7Annual Enrollment Period (Open Enrollment)Anyone with Medicare can join, switch, or drop a Medicare Advantage or Part D plan.
  • January 1 – March 31Medicare Advantage Open EnrollmentIf you're already in a Medicare Advantage plan, you can make one change.
  • January 1 – March 31General Enrollment PeriodFor people who missed their first chance to sign up for Part B.
  • VariesSpecial Enrollment PeriodTriggered by life events like moving or losing other coverage.

Dates are set by Medicare and apply nationwide. Confirm your personal windows at Medicare.gov or 1-800-MEDICARE.

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The parts of Medicare

Part A covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health care. Most people pay no premium for Part A.

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When can you enroll? An interactive year

JFMAMJJASOND
October 15 – December 7 — anyone with Medicare can join, switch, or drop a Medicare Advantage or Part D plan. Changes take effect January 1.

Enrollment windows are federal and the same nationwide. Confirm your personal dates at Medicare.gov or 1-800-MEDICARE.

Good to know

Frequently asked questions

How many Medigap insurers are listed for Montana for 2027?
Medicare.gov's Medigap policy search for ZIP code 59101 lists 23 insurers. Offerings can vary by ZIP code and by age, sex, and tobacco use, so check your own ZIP on Medicare.gov.
Can I be turned down for a Medigap policy in Montana?
Inside your six-month Medigap Open Enrollment Period, which starts when you are 65 or older and enrolled in Part B, insurers in Montana must sell you any policy they offer without using your health history against you. Outside that window, medical underwriting may apply unless a guaranteed-issue right fits your situation, including when a Medicare Advantage plan is not returning.
Does a Medigap plan include my prescription drugs?
No. Medigap sold today does not include prescription drug coverage. You would enroll in a stand-alone Medicare Part D plan separately, with Annual Enrollment running October 15 – December 7, 2026, for coverage effective January 1, 2027.
What if my Medicare Advantage plan is not offered in Montana in 2027?
CMS Landscape files show 12 Medicare Advantage plans offered in Montana in 2026 will not be offered anywhere in the state in 2027. If you are in one of those plans, federal rules give you a guaranteed-issue right to buy certain Medigap plans; the specifics are at Medicare.gov or by calling 1-800-MEDICARE.
Sources & further reading
  • CMS — Medicare Supplement Insurance (Medigap) rules (medicare.gov)
  • CMS — Medicare enrollment periods (medicare.gov)

For personalized answers, contact Medicare.gov or 1-800-MEDICARE.

Sources and methodology

Figures cited in this article

  • Medicare.gov Medigap policy search (ZIP 59101): the list of 23 insurers and the plan letters each sells in Montana.
  • CMS Landscape Source File: the count of 12 Medicare Advantage plans offered in Montana in 2026 and not offered anywhere in the state in 2027.
  • CMS — Medicare Supplement Insurance (Medigap) rules (medicare.gov): the six-month Medigap Open Enrollment Period, guaranteed-issue rights, and the closure of Plans C and F to those newly eligible on or after January 1, 2020.
  • CMS — Medicare enrollment periods (medicare.gov): the 2027 Annual Enrollment dates and January 1, 2027 effective date.
  • CMS — Part D program parameters for 2027: the $2,400 out-of-pocket cap, $700 maximum deductible, and $41.33 base beneficiary premium.
  • Social Security Administration: the 3.6 percent cost-of-living adjustment announced October 14, 2026 for January 2027 benefits.

How we put this together: area counts come from the CMS files listed above for the county that contains this city, program figures come from CMS, Medicare.gov and the Social Security Administration, and no plan is ranked or recommended.

By The Medicare Desk · Published . For personalized answers, contact Medicare.gov or 1-800-MEDICARE.

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This page was last updated: October 2026.

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