Medigap in Montana (2027): How Medicare Supplement Plans Work

A Medigap policy fills the deductibles and coinsurance Original Medicare leaves behind — and because the plans are standardized by law, the letter matters more than the company. This guide explains how they work, and what each covers, for people in Montana, in plain terms for 2027.

One fact shapes every Medicare decision in Montana: your county, not your state, sets your options. Neighboring counties can look surprisingly different, which is exactly why the guides here are local.

About 30% across Montana have chosen Medicare Advantage over Original Medicare, though that share swings a lot depending on where you live.

Ahead: the companies active statewide, how Original Medicare, Advantage, Medigap and Part D fit together, the shared 2027 costs, enrollment windows, free unbiased help, and a guide for every Montana city.

Where Medigap fits in your Medicare

Original Medicare (Part A and Part B) pays most of your covered costs — but not all. You're left with deductibles, coinsurance, and copays, and there's no annual out-of-pocket maximum in Original Medicare on its own. That open-ended exposure is the gap Medigap policies are designed to help close.

Medigap policies are sold by private insurers but standardized by the federal government and labeled with letters (such as Plan G or Plan N). Because they're standardized, a given lettered plan covers the same things no matter who sells it — what differs is price and service. Medigap pairs with Original Medicare, not Medicare Advantage, and doesn't include drugs, so people on this path usually add a stand-alone Part D plan.

This guide explains how the standardized plans and your enrollment rights work in Montana. We explain the framework — we don't rank plans or quote specific premiums.

What Medicare costs in 2027

It helps to separate the costs everyone shares from the costs that vary by plan. The program-level numbers here are set nationally — the same whether you're in a big city or a rural county.

Part B premium. Most people pay the standard Part B premium of $202.90 a month in 2026 (2026 amount; 2027 figure will be posted when CMS releases it). Part A is premium-free for most people who worked and paid Medicare taxes long enough.

Part D drug costs. In 2027, a Part D plan's yearly deductible can be no more than $700, and a $2,400 cap limits what you pay out of pocket for covered prescriptions across the year — a real change for anyone with high drug costs.

Higher earners pay more for Parts B and D through an income-related adjustment called IRMAA, which for 2026 starts above $109,000 in annual income for an individual and is based on your 2024 tax return. Most people fall below that line and pay the standard amounts. The 2027 brackets will be posted when CMS releases them.

Plan-specific costs. What an individual plan charges — its premium, deductible, copays, and what it covers — varies by plan and changes yearly. We don't publish those figures or rank plans; Medicare's Plan Finder shows the current details for your situation, and a licensed agent can walk you through them.

When you can enroll or make changes

Medicare's enrollment windows are federal — the same nationwide — so the timing below applies wherever you live.

Your first window (IEP). When you're new to Medicare, your Initial Enrollment Period is the 7-month window around your 65th birthday month. Signing up on time helps you avoid late penalties that can follow you for years.

Annual Enrollment Period (AEP). Each fall, from October 15 – December 7, anyone with Medicare can join, switch, or drop a Medicare Advantage or Part D plan. Changes take effect January 1.

Medicare Advantage Open Enrollment. From January 1 – March 31, if you're already in an Advantage plan you get one chance to switch plans or return to Original Medicare.

Special Enrollment Periods can also open after certain life events, like moving or losing other coverage. The interactive calendar further down lays the year out visually.

Getting unbiased help in Montana

You never have to make these decisions alone, and you don't have to pay for good help. A few free, trustworthy starting points:

Medicare.gov and 1-800-MEDICARE (TTY 1-877-486-2048) are the official sources for plan details and the Plan Finder. Licensed agents can also compare options with you and handle enrollment.

And to be clear about who we are: MyMedicarePlans.org is a privately owned, independent educational resource. We are not Medicare, not a government agency, and not affiliated with one. We publish plain-language information to help you get oriented — then point you to the official sources and licensed professionals for decisions about specific plans.

Montana cities

Pick your city for the county-level picture, the companies active in your area, and local guides: