Medicare Supplement

Does Your St. Louis Medigap Letter Really Matter?

If you live in St. Louis and you are shopping for a Medicare Supplement policy — often called Medigap — the first thing to understand is that the coverage is federally standardized. That means a Plan G sold by one insurer in Missouri covers the same medical benefits as a Plan G sold by any other insurer here. The letter tells you what is covered. The company name on the front of the policy does not change the benefits inside.

The letters do the heavy lifting

That is the piece most St. Louis shoppers say clicks last, so we are putting it first.

Which letters you can buy in Missouri today

Missouri follows the federal standardized set. People newly eligible for Medicare today can choose from Plans A, B, D, G, high-deductible G, K, L, M, and N. Plans C and F remain available only to people who were eligible for Medicare before January 1, 2020, because both plans cover the Part B deductible and federal law closed that door for newer enrollees.

Three states — Massachusetts, Minnesota and Wisconsin — standardize their Medigap plans differently. Missouri is not one of them, so the federal letters apply in St. Louis.

How Medigap fits with Original Medicare and Part D

A Medigap policy is a supplement, not a replacement. You keep Original Medicare (Part A hospital and Part B medical) as your primary coverage, and the Medigap policy pays some of the out-of-pocket costs Original Medicare leaves behind — things like coinsurance and, depending on the letter, the Part A deductible.

Medigap does not cover prescription drugs. If you want drug coverage, you generally add a stand-alone Part D plan. A few 2026 Part D facts worth keeping in mind:

• The Part D out-of-pocket cap is $2,100 for 2026.
• The Part D maximum deductible is $615.
• The old coverage gap ("donut hole") is gone as of 2025 — Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread drug costs across the calendar year in monthly installments.

One more note: Medigap and Medicare Advantage do not mix. If you enroll in a Medicare Advantage plan, you cannot also use a Medigap policy.

The Missouri rules that shape your choice

Two rules matter most when you are timing a Medigap purchase.

Your Medigap Open Enrollment Period. This is a one-time, six-month window that starts the month you are 65 or older AND enrolled in Part B. During this window, insurers in Missouri must sell you any Medigap plan they offer, at their published rate, without asking health questions. Outside this window, in most cases, insurers can use medical underwriting and can decline you or charge more based on health.

Guaranteed-issue rights. Federal law gives you the right to buy certain Medigap plans without underwriting in specific situations — for example, if your Medicare Advantage plan leaves your area, or if you move out of a plan's service area. Missouri may recognize additional rights beyond federal law; for the current list, check with the Missouri Department of Commerce and Insurance or CLAIM.

If you are thinking about switching Medigap policies later, ask the new insurer what underwriting will apply before you drop your current plan.

What actually differs between insurers

Since the benefits inside each letter are set by law, insurers compete on three things:

• Price. Two companies can charge very different premiums for the exact same Plan G. Rates also change over time.
• How rates are calculated. Missouri insurers may use community-rated, issue-age-rated, or attained-age-rated pricing. That affects how your premium changes as you get older.
• Household discounts, customer service, and extras. Some carriers offer small discounts (for example, for spouses in the same household) or add-ons like fitness benefits.

We cannot quote premiums here, and we do not rank carriers. What we can tell you is that comparing the same letter across multiple insurers is the apples-to-apples way to shop.

The Missouri carrier list

The table below lists every insurer selling Medigap in Missouri and the letters each one offers. AARP – UnitedHealthcare Insurance Company, Aetna Health and Life Insurance Company, AFLAC, Bankers Life, Blue Cross and Blue Shield of Kansas City, HealthSpring National Health Insurance Company, Humana, Insurance Company of North America, LifeShield National Insurance Company, Lumos Insurance, Medico Life and Health Insurance Company, Mutual of Omaha, Old Surety Life Insurance Company, Physicians Life Insurance Company, State Farm Mutual Automobile Insurance Company, United American Insurance Company, USAA Life Insurance Company, and Wisconsin Physicians Service Insurance Corporation all file Medigap policies in the state.

Not every carrier sells every letter. If you have a specific letter in mind — say Plan G or Plan N — narrow the table to the companies that offer it, then compare.