Medicare Supplement

In North Charleston, why a Medigap bill can climb while the benefits stay put

NORTH CHARLESTON, S.C. — If you own a Medicare Supplement policy — or you're shopping for one during this fall's enrollment season — here is a quirk worth understanding before the next renewal notice arrives: the benefits on a lettered Medigap plan are standardized and cannot change, but the premium you pay for those benefits can.

That is because insurers use one of three pricing methods to set what a Medigap policy costs, and each method behaves differently as you age and as medical costs shift. Which methods are offered depends on the insurer and the state, according to the Centers for Medicare & Medicaid Services.

What "standardized benefits" actually means

Medigap policies sold today come in lettered plans — A, B, D, G, K, L, M and N, plus high-deductible versions of G and F where available. Federal rules require that a Plan G from one insurer cover the same gaps in Original Medicare as a Plan G from another. Two people in Charleston County holding the same lettered plan get the same coverage rules, even if their monthly bills are not the same.

So when a premium goes up, it is not because benefits were quietly trimmed. It is because of how the insurer prices the policy — and the broader pressures of health care costs.

The three pricing methods, in plain language

Community-rated (also called no-age-rated). Everyone who buys the same policy from the same insurer pays the same base premium, regardless of age. A 66-year-old and a 78-year-old signing up today would start at the same rate. The premium can still change over time, but not because you personally got older.

Issue-age-rated (also called entry-age-rated). Your premium is based on the age you were when you bought the policy. Buy at 65 and your base rate is tied to that starting age; it will not go up simply because you turn 70 or 80. It can, however, still rise for other reasons.

Attained-age-rated. Your premium is based on your current age and typically increases as you get older — sometimes every year, sometimes at set age bands. These policies often start lower at 65 and climb from there.

Which of these methods a particular insurer uses — and which are permitted or common in a given state — varies. If you live in North Charleston, ask the insurer or agent directly which method applies to the policy you are considering.

Why the bill can still rise, even with locked-in benefits

No matter which pricing method an insurer uses, two forces sit outside the method itself:

• Inflation. Medical care, prescription drugs and hospital services generally cost more each year, and premiums often reflect that.
• Claims experience. Insurers look at how much the group of people holding a particular plan is actually using care. If claims across that pool rise, premiums can be adjusted for everyone in it.

With attained-age policies, add a third factor: your own age. That is the piece a shopper can miss when comparing a low starting premium against a slightly higher one from an issue-age or community-rated policy.

What to check before you sign — or renew

North Charleston is in Charleston County, and Medigap availability is regulated at the state level in South Carolina. Before choosing a policy, the CMS Medigap consumer guidance suggests asking:

• Which pricing method does this policy use?
• How often has the insurer raised premiums on this plan in recent years?
• Am I in my Medigap Open Enrollment Period (the six months starting when you're 65 and enrolled in Part B), when insurers generally cannot use medical underwriting to deny or price up a policy?

Outside that open enrollment window, your ability to switch Medigap plans without health questions is limited in most states.

How this fits with the rest of your Medicare

Medigap is separate from Medicare Advantage and from Part D drug coverage. A few 2026 program-level facts worth keeping in mind while you review your setup:

• Part D's annual out-of-pocket cap is $2,100 in 2026.
• The Part D maximum deductible is $615.
• The old coverage gap ("donut hole") was eliminated in 2025; Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread drug costs across the year in monthly payments.
• IRMAA income-based surcharges start above $109,000 for a single filer in 2026.
• The Annual Enrollment Period runs Oct. 15 through Dec. 7. Medicare Advantage Open Enrollment runs Jan. 1 through March 31.