What is Medicare Supplement
Medicare Supplement Insurance — also known as Medigap — is private insurance that helps pay the “gaps” in Original Medicare (Parts A and B).
It is designed to cover out-of-pocket costs such as deductibles, copayments, and coinsurance that Medicare doesn’t pay.
Medigap policies are standardized and regulated by the Centers for Medicare & Medicaid Services (CMS) and are offered by private insurance companies.
Each Medigap plan is identified by a letter (A, B, C, D, F, G, K, L, M, N) and offers a different level of coverage, but the benefits for each lettered plan are identical across all insurers.
Table of Contents:
Medicare Supplement Coverage
Medigap Covered Services
Medigap Non-Covered Services
Medigap policies do not cover everything. They generally do not include:
Medicare Supplement Eligibility
You are eligible to buy a Medigap policy if:
You must continue paying your Part B premium in addition to your Medigap premium.
Medicare Supplement (Medigap) plans are standardized policies labeled A–N that help pay Original Medicare’s gaps (deductibles, coinsurance). For the same lettered plan, benefits are identical across insurers; what varies are premium, underwriting, rating method, and discounts—not provider networks (you can see any doctor who accepts Medicare). Medigap does not include Part D drug coverage. Due to MACRA, Plans C and F (including High-Deductible F) aren’t available to people newly eligible for Medicare on/after 1/1/2020; Plan G/HD-G are the closest alternatives. Policies are guaranteed renewable as long as premiums are paid.
2025 Deductibles and Maximum-Out-Of-Pocket (MOOP):
Medicare Part A Deductible = $1,620
Medicare Part B Deductible = $257
High-Deductible Plan F Deductible Amount = $2,870
High-Deductible Plan G Deductible Amount = $2,870
Plan K Maximum-Out-Of-Pocket = $7,220
Plan L Maximum-Out-Of-Pocket = $3,610
What is Medicare Access and CHIP Reauthorization Act (MACRA)
It’s a federal law passed by Congress that prohibited Medigap plans from covering the Part B deductible for people newly eligible for Medicare on or after January 1, 2020, leading to the phaseout of Plans C, F, and High-Deductible F for those new beneficiaries.
If you were newly eligible on/after 1/1/2020, you can’t buy C/F/HD-F. Most people choose Plan G (or High-Deductible G) as the closest alternative—same benefits as F except it does not pay the Part B deductible.
Monthly Premium
Premiums vary by plan letter, age, location, and company.
Average monthly premiums (Michigan 2025):
Insurance companies use three different rating methods:
Rating Type | How It Works |
Community-rated | Same premium for everyone, regardless of age. |
Issue-age-rated | Based on your age when you first buy the policy; doesn’t increase due to age. |
Attained-age-rated | Starts low but increases as you getolder. (Most common) |
Monthly Premium Determination Factors
Here are the main factors that drive a Medicare Supplement (Medigap) monthly premium:
Medicare Supplement Plan Cost-Sharing
While Medigap premiums are higher than Part C plans, they offer predictable costs and nationwide flexibility.
Example (2025):
If you have Plan G:
No network restrictions — you can see any doctor or hospital that accepts Medicare.
To enroll in a Medicare Supplement (Medigap) plan, you must have Medicare Parts A and B and live in the plan’s service area. The best time to enroll is during your 6-month Medigap Open Enrollment Period, which starts when you’re 65 or older and enrolled in Part B. During this time, you have guaranteed acceptance—no health questions or denials. After this window, you can still apply, but insurers may use medical underwriting and charge more or deny coverage. Some people qualify for Guaranteed Issue rights if they lose coverage or leave a Medicare Advantage plan. Plans and costs vary by state, and under MACRA, Plans C and F are unavailable to those newly eligible for Medicare after January 1, 2020.
Enrollment Period | When You Can Enroll | Underwriting Rules |
Medigap Open Enrollment Period | 6-month window starting the month you are 65+ and enrolled in Part B | Guaranteed Issue: No health questions or denials |
Special Guaranteed Issue Rights | Within 63 days of losing certain coverage (e.g., MA plan trial right, employer coverage ends) | Guaranteed Issue applies |
Outside Open Enrollment | Any time of year | Medical underwriting may apply |
Medigap Open Enrollment Period
Special Guaranteed Issue Rights
Outside Open Enrollment
Medicare Supplement (Medigap) underwriting is the health-screening process most insurers use when you apply outside your one-time Open Enrollment Period (the first 6 months you’re 65+ and enrolled in Part B) or outside a Guaranteed-Issue (GI) situation. During underwriting, a carrier can review your medical history, recent conditions and treatments, medications, height/weight, tobacco use, and sometimes doctor or hospital records. Based on that review, the company may approve you, charge a higher premium, add a waiting period for pre-existing conditions (up to 6 months if you lacked recent creditable coverage), or decline the application. In GI situations—like losing qualifying employer coverage or using the “trial right” after trying an MA plan—carriers must accept you with no health questions. Some states add extra protections (e.g., birthday or anniversary rules for switching). Because rules vary by state and carrier, it’s smart to review timing and eligibility before applying.
Underwriting Area | Typical Rule | Common Look-Back | Notes |
Eligibility window | If not in Medigap Open Enrollment or no GI right → medical underwriting required | — | OEP/GI generally bypass underwriting. |
Phone interview | Short health interview often required | Current | Confirms application answers. |
Rx history check | Carriers review prescription fill history | 12–24 months | Confirms conditions/ stability. |
MIB/records | May check MIB and request medical records | 12–24 months | Not all carriers use MIB. |
Height/Weight (BMI) | Must fall within carrier build chart | Current | Outside range → decline or rating. |
Tobacco use | Smoker rates higher | 12 months | Some carriers require smoke-free period for best rate. |
Recent hospitalization/ surgery | Recent inpatient stay/major surgery may decline/postpone | 3–12 months | Elective or pending surgery often postpones. |
Pending tests/referrals | Undiagnosed symptoms or pending work-ups → postpone | Until resolved | Must have diagnosis/treatment plan. |
Oxygen use | Current oxygen use usually decline | Current | Includes nocturnal O2 for COPD in many guides. |
Mobility/ADLs | Wheelchair, ADL assistance, home health, or nursing facility → often decline | Current | Level of assistance matters. |
Cancer (active/recent) | Active treatment or recent diagnosis often decline | 2–5 years | In remission beyond window may be OK. |
Cardiac events | Recent MI, stent/bypass, heart failure exacerbation → decline/postpone | 6–24 moths | Stable CAD with meds may pass. |
CHF (heart failure) | Symptomatic or recent hospitalization → usually decline | 2 years | Controlled, no recent events may pass with some carriers. |
Stroke/TIA | Recent stroke/TIA → decline/postpone | 2 years | Older events with full recovery may pass. |
Diabetes | Insulin + complications (neuropathy, retinopathy) → decline with many carriers | 2 years | Oral meds and A1c control may pass. |
CKD/ESRD | Dialysis/ESRD → usually decline | Current | Earlier CKD stages vary by carrier. |
Dementia/Alzheimer’s | Usually decline | Current | Cognitive screens may be used. |
Substance abuse | Active alcohol/drug abuse → decline | 2 years (sustained recovery) | Documentation of recovery may help. |
Mental health | Severe, unstable, or recent psych hospitalization → decline/postpone | 1–2 years | Stable, well-managed often OK. |
Sleep apnea | Untreated, severe → postpone/decline | Current | Treated with CPAP and compliant often OK. |
Auto-declines (varies) | Organ transplant, metastatic cancer, ALS, schizophrenia (varies) → often decline | — | Carrier-specific. |
State exceptions | Some states have birthday/anniversary rules or continuous access | — | Eases switching without underwriting. |
Rate classes/discounts | Household/EFT discounts; tobacco surcharge; gender in some states | Current | Community/issue/attained-age rating affects price. |
Important: Rules differ by carrier and state (and by plan letter). Guaranteed Issue or Open Enrollment generally overrides underwriting. If you tell me your state, age, tobacco status, and key conditions, I can summarize likely carriers that are more lenient and where you may qualify.
Medicare Supplement Trial-Right
Frequently Asked Questions (FAQs)
Yes if you have certain disabilities, End-Stage Renal Disease (ESRD), or ALS (special rules apply).
Yes, generally after the first units each calendar year (who pays first can depend on whether the provider gets free blood).