Medigap: Background and Statistics
May 12, 2023
Medicare is a federal program that pays for covered health care services of qualified
beneficiaries, which include most individuals aged 65 and older and certain younger
Michele L. Malloy
individuals with permanent disabilities. Original Medicare (Parts A and B) provides
Research Librarian
broad protection against the costs of many covered services; however, beneficiaries can

still face significant out-of-pocket spending. Many Medicare beneficiaries therefore
have some form of additional coverage (private or public) to pay for some or all of their

out-of-pocket costs.
Medigap (or “Medicare Supplement Insurance”) is private insurance that is designed to cover cost-sharing gaps
under original Medicare, such as deductibles, coinsurance, and copayments. Medigap is not equivalent to
Medicare and is distinct from Medicare Part B (“Supplementary Medical Insurance”), Medicare Part C
(“Medicare Advantage”), and Part D (which covers outpatient prescription drug benefits).
Medigap enrollment is voluntary. To be eligible to purchase a Medigap plan, Medicare beneficiaries must be
enrolled in both Part A and Part B, and not enrolled in a Medicare Advantage plan. As of 2021, 14.6 million
Medicare beneficiaries were enrolled in Medigap plans. Medigap is financed through premiums paid by
beneficiaries who enroll in Medigap. Medigap plans are regulated by states, and Congress has enacted legislation
to standardize Medigap plans and mandate consumer protections.

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Medigap: Background and Statistics

Introduction and Background
This report provides brief descriptions of Medicare and Medigap, including the different types of
Medigap plans on the market, which are identified by letter and financing. The report describes
sources of Medigap data and their limitations, and it concludes with tables providing enrollment
trends and demographics.
Medicare
Medicare is a federal program that pays for covered health care services of qualified
beneficiaries, which include most individuals aged 65 and older and certain younger individuals
with permanent disabilities.
Medicare consists of four parts:1
• Part A (Hospital Insurance) covers inpatient hospital services, skilled nursing
care, some home health care, and hospice care.
• Part B (Supplementary Medical Insurance) covers physician and non-physician
practitioner services, outpatient services, some home health care, durable medical
equipment, clinical laboratory and other diagnostic tests, preventive services,
certain prescription drugs and biologics, and other medical services.
• Part C (Medicare Advantage, or MA) is a managed care plan option offered by
private insurers that covers all Part A and Part B services, except for hospice
care.2
• Part D is a voluntary option offered through private insurers that covers
outpatient prescription drug benefits.
Part A and Part B together comprise original Medicare, which pays providers of covered benefits
on a fee-for-service basis.3 In contrast, the private insurers that offer MA and Part D plans are
paid under a capitation model.4
Medigap
Medigap (or “Medicare Supplement Insurance”) is private insurance designed to provide
secondary coverage to original Medicare (Parts A and B). Medigap is not equivalent to Medicare
and is distinct from Part B (“Supplementary Medical Insurance”), Part C (“Medicare
Advantage”), and Part D (which covers outpatient prescription drug benefits).

1 For more information on Medicare, see CRS Report R40425, Medicare Primer.
2 Medicare Advantage (MA) enrollees may choose hospice care, but, in general, that care is then paid for by Medicare
Part A.
3 Fee for service is a payment model in which health care providers and facilities are paid a separate amount for each
service or item furnished. In general, under original Medicare, the government pays for covered items and services
using different prospective payment systems or fee schedules that pay per unit, where a unit may be, for example, a
spell of illness, an inpatient diagnosis, or a piece of equipment for home use.
4 Whereas MA plans are paid under capitation, health care providers and facilities in MA plan networks are paid based
on the conditions of their contracts with the MA plans. Under a capitation system, health plans receive a set amount of
money for each enrollee, for a designated period of time, regardless of the level of service usage by the enrollee. Under
those contracts, provider and facility payments may be structured as fee for service or capitation (or partial capitation),
and portions of the payments may be conditional on meeting quality or performance benchmarks. For more information
on capitation, see https://innovation.cms.gov/key-concept/capitation-and-pre-payment.
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Although original Medicare provides broad protection against the costs of many covered services,
beneficiaries can still face significant out-of-pocket spending. Many Medicare beneficiaries
therefore have some form of additional coverage (private or public) to pay for some or all of their
out-of-pocket costs.
Medigap is one type of private supplemental insurance and is designed to cover cost-sharing gaps
under original Medicare, such as deductibles, coinsurance, and copayments.5 Other sources of
coverage that Medicare beneficiaries may have include retiree coverage through a former
employer, group health care coverage through a current employer, and/or coverage through other
governmental sources, such as Medicaid, the Department of Veterans Affairs (VA), or the
TRICARE health care program for military personnel and veterans.
Eligibility and Enrollment
Medigap enrollment is voluntary. To be eligible to purchase a Medigap plan, a Medicare
beneficiary must be
• enrolled in both Part A and Part B, and
• not enrolled in an MA plan.
Applicable statutory and regulatory requirements and consumer protections are outlined below.
As of 2021, 14.6 million Medicare beneficiaries were enrolled in Medigap plans, as shown in
Table 3. Medigap enrollment is tracked primarily through the National Association of Insurance
Commissioners (NAIC),6 an association of the insurance commissioners, though there are other
sources. Selected statistics are presented in the “Data and Sources” section of this report.
Financing
Medigap is financed through premiums paid by Medicare beneficiaries who choose to enroll in
Medigap. Retirees may have premiums paid on their behalf by their former employers. There are
no federal contributions toward Medigap premiums.
Statutes and Regulations
Medigap plans are regulated by states, which may use NAIC-developed model legislation.7 As
part of the Medicare Catastrophic Coverage Act of 1988 (MCCA; P.L. 100-360),8 Congress
required that state Medigap plans meet or exceed NAIC guidelines. States may either adopt the
NAIC model and any subsequent revisions or enact regulations that are more stringent than those
in the NAIC model. If the requirement is not met, then federal model standards are imposed on
the state.

5 See “What’s Medicare Supplement Insurance (Medigap)?” at https://www.medicare.gov/supplements-other-
insurance/whats-medicare-supplement-insurance-medigap.
6 The National Association of Insurance Commissioners (NAIC) is an association of the insurance commissioners of
the states and territories. NAIC “is the U.S. standard-setting and regulatory support organization created and governed
by the chief insurance regulators from the 50 states, the District of Columbia and five U.S. territories,” at
https://content.naic.org/sites/default/files/about-faq.pdf.
7 National Association of Insurance Commissioners (NAIC), “Model Regulation to Implement the NAIC Medicare
Supplement Insurance Minimum Standards Model Act,” 2022, at https://content.naic.org/sites/default/files/model-law-
651.pdf.
8 Parts of this law were repealed under P.L. 101-234, but the Medigap provisions were not repealed.
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Medigap: Background and Statistics

Congress has also enacted legislation to standardize Medigap offerings and mandate consumer
protections, including
• The Omnibus Budget Reconciliation Act of 1990 (OBRA-90; P.L. 101-508), which
replaced previous voluntary guidelines with federal standards, including standardized
plans, guaranteed plan renewal, and medical loss ratio standards.
• The Medicare Prescription Drug Improvement and Modernization Act of 2003
(MMA; P.L. 108-173), which established the Medicare Prescription Drug (Part
D) benefit and barred Medigap plans from offering drug coverage to new
beneficiaries. Provisions of the MMA also ordered the Department of Health and
Human Services (HHS) to request that NAIC develop additional standardized
Medigap plans.
• The Medicare Improvement for Patients and Providers Act of 2008 (MIPPA; P.L. 110-
275), which required participating insurers to offer certain standardized plans.
In addition to the standardization of plans, legislation, including the laws highlighted above, has
afforded consumer protections to Medigap insurance plan purchasers who are at least aged 65.
These protections include
Guaranteed Issue Protections.9 During the initial six-month open enrollment period for
new beneficiaries,10 insurers cannot refuse to sell an individual any Medigap policy that
the insurer offers. Plans cannot exclude coverage for pre-existing health conditions, and
insurers cannot charge more based on an individual’s health history. Medicare
beneficiaries also have some guaranteed issue protections after their initial open
enrollment period, including
• the ability to buy a different plan following changes in residence or
employment, in which they are forced to change plans,
• “trial rights” to switch from Medicare Advantage to Original Medicare and
obtain a Medigap policy within the initial year of enrollment, and
• “no fault rights” that allow a beneficiary guaranteed issue if an insurer no
longer offers an enrollee’s plan or has misled an individual.
Some states have additional open enrollment rights according to state law.
Guaranteed Renewal.11 The insurer cannot cancel a Medigap plan as long as the
beneficiary remains enrolled and pays the premium.
There is no federal requirement that insurers sell Medigap plans to disabled individuals under the
age of 65. Some states require that Medigap plans be available to some or all disabled Medicare
beneficiaries. In other states, insurers may choose to sell Medigap plans to younger disabled
beneficiaries even though there is no requirement that they do so.

9 Centers for Medicare & Medicaid Services (CMS) and NAIC, “Choosing a Medigap Policy: A Guide to Health
Insurance for People with Medicare, 2023,” p.21, at https://www.medicare.gov/publications/02110-medigap-guide-
health-insurance.pdf.
10 The Medigap open enrollment period is “a one‑time‑only, 6‑month period when federal law allows you to buy any
Medigap policy you want that’s sold in your state. It starts in the first month that you’re covered under Medicare Part
B, and you’re 65 or older. During this period, you can’t be denied a Medigap policy or charged more due to past or
present health problems.” CMS and NAIC, “Choosing a Medigap Policy: A Guide to Health Insurance for People with
Medicare, 2023,” p.50, at https://www.medicare.gov/publications/02110-medigap-guide-health-insurance.pdf.
11 CMS and NAIC, “Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare, 2023,” p.36,
at https://www.medicare.gov/publications/02110-medigap-guide-health-insurance.pdf.
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In most cases, Medigap enrollees do not have a federal right to change Medigap policies beyond
the open enrollment period unless they are eligible under the guaranteed issue rights outlined
above.
Medigap plan insurers must meet certain federal requirements.
Required plans. If an insurer offers any Medigap plans, it must offer the basic plan (Plan
A; see Table 1). If an insurer offers any other plans, it must at least offer Plan C or Plan F
to individuals who are not new to Medicare on or after January 1, 202012, and either Plan
D or Plan G to individuals who are new to Medicare.13
Premiums. The three rating options or methods by which an insurer can set premiums for
health insurance policies within Medigap are (1) the community rating option (all
individuals in a plan pay the same premium and it does not increase with a beneficiary’s
age), (2) the issue-age rating option (the premium is based on a beneficiary’s age when
the policy was first purchased), or (3) the attained-age rating option (the premium is
based on a beneficiary’s current age).14
Medical Loss Ratios (MLRs).15 MLRs measure the share of enrollee premiums that
health insurers spend on medical claims as opposed to other non-claims expenses, such as
administrative fees or profits earned, over a set time period (e.g., a calendar year or plan
year). These measures are intended to ensure that health plans meet a minimum benefit
standard. Medigap plans must return to the policyholders, in the form of aggregate
benefits, at least 75% of the aggregate amount of premiums in the case of group policies
and at least 65% of the aggregate amount of premiums in the case of individual policies.16
Federal statutes and regulations governing Medigap are
• 42 U.S.C. §1395ss: Certification of Medicare supplemental health insurance
policies17 and
• 42 C.F.R. Part 403 Subpart B - Medicare Supplemental Policies.18

12 P.L. 114-10 Medicare Access and CHIP Reauthorization Act of 2015 (MACRA) prohibits the sale of Medigap plans
with first-dollar coverage to an individual who is a “newly eligible Medicare beneficiary.” Plans C and F included first-
dollar coverage and can no longer be sold to people new to Medicare on or after January 1, 2020. However, if
beneficiaries were eligible for Medicare before January 1, 2020 but haven’t yet enrolled, they may be able to buy Plan
C or F. See 82 FR 41684, https://www.federalregister.gov/documents/2017/09/01/2017-18605/medicare-program-
recognition-of-revised-naic-model-standards-for-regulation-of-medicare-supplemental.
13 CMS and NAIC, “Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare, 2023,” p.10,
at https://www.medicare.gov/publications/02110-medigap-guide-health-insurance.pdf.
14 CMS and NAIC, “Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare, 2023,” p.17,
at https://www.medicare.gov/publications/02110-medigap-guide-health-insurance.pdf.
15 Medigap Medical Loss Ratio (MLR) requirements predate those established within the Patient Protection and
Affordable Care Act (ACA; P.L. 111-148, as amended), and the ACA MLRs are higher than Medigap MLRs. See CRS
Report R42735, Medical Loss Ratio Requirements Under the Patient Protection and Affordable Care Act (ACA): Issues
for Congress.
16 Federal Medigap regulations are at 42 C.F.R. §403.200, https://www.ecfr.gov/current/title-42/chapter-IV/subchapter-
A/part-403/subpart-B. Under §403.232, to be certified by CMS, a Medigap policy must meet NAIC model standards,
loss ratio standards, and any state requirements applicable to a policy. See NAIC, “Model Regulation to Implement the
NAIC Medicare Supplement Insurance Minimum Standards Model Act”, 2022, at https://content.naic.org/sites/default/
files/model-law-651.pdf.
17 42 U.S.C. §1395ss, at https://uscode.house.gov/view.xhtml?hl=false&edition=prelim&req=granuleid%3AUSC-
prelim-title42-section1395ss&f.
18 42 C.F.R. Part 403, Subpart B, at https://www.ecfr.gov/current/title-42/chapter-IV/subchapter-A/part-403/subpart-B.
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Plan Types and Benefits
Federal statutes and regulations require Medigap plan standardization. Each plan is identified by
letter and associated with a specific benefit package. For example, all Plan A policies, regardless
of insurer, have the same common benefit package.19 Insurers may offer any of the standardized
plans in Table 1, but insurers are not allowed to sell certain plans to newly eligible Medicare
beneficiaries.20 Medigap plans range from covering all allowable Medicare copayments,
coinsurance, and deductibles to more limited options.
Medigap policies are sold in both the individual and the group health insurance markets. Whether
purchased in the individual or the group market, each Medigap policy covers one individual.
Standardized Medigap policies are guaranteed renewable by enrollees so long as the plan remains
for sale in the geographic market.
Federal Medigap plan standards do not apply to insurers in Massachusetts, Minnesota, and
Wisconsin. These states had their own standardized Medigap plans prior to the enactment of the
federal standardization requirements, so they were exempted from federal standardization. Their
state standardized plans are called waivered state plans.
• Massachusetts’s Medigap state plans fall into three categories: “Core,”
“Supplement 1,” and “Supplement 2.”21 The Massachusetts Division of Insurance
licenses insurers, reviews plans, and provides annual guides to available plans
and carriers,22 and the laws of the Commonwealth of Massachusetts address
state-level requirements for these plans.23
• In Minnesota, state versions of some of the federal standardized plans are
available, as well as the state “Basic Plan” and “Extended Basic Plan.”24 In
addition to the federal standards, these plans cover state-mandated benefits such
as diabetic equipment and supplies, routine cancer screening, reconstructive
surgery, and immunizations. The Minnesota Department of Commerce reviews
and approves Medigap plans sold in Minnesota.25

19 The term plan refers to all the Medigap insurance contracts with a common benefit package (e.g., Plan A), and the
term policy refers to an insurance contract sold by an insurer to a beneficiary (e.g., United Healthcare’s Plan A).
20 Medicare.gov, “How to Compare Medigap Policies,” at https://www.medicare.gov/supplements-other-insurance/
how-to-compare-medigap-policies. As of January 1, 2020, Medigap plans sold to individuals newly enrolled in
Medicare are not allowed to provide coverage of the Part B deductible. Plans C and F included first-dollar coverage and
can no longer be sold to people new to Medicare on or after January 1, 2020. However, if beneficiaries were eligible for
Medicare before January 1, 2020 but haven’t yet enrolled, they may be able to buy Plan C or F. See 82 FR 41684,
https://www.federalregister.gov/documents/2017/09/01/2017-18605/medicare-program-recognition-of-revised-naic-
model-standards-for-regulation-of-medicare-supplemental. New enrollees may purchase Plans D and G that are similar
to Plans C and F, except for coverage of the Part B deductible. In general, insurance companies that sell Medigap
policies are not required to offer every Medigap plan, must offer Medigap Plan A if they offer any Medigap policy, and
must offer Plan C or Plan F if they offer any plan (or D or G if offered to those newly eligible as of 2020).
21 Medicare.gov, “Medigap in Massachusetts,” at https://www.medicare.gov/supplements-other-insurance/how-to-
compare-medigap-policies/medigap-in-massachusetts.
22 Commonwealth of Massachusetts Division of Insurance, “Medicare and Medigap Coverage,” at
https://www.mass.gov/info-details/health-care-coverage-information#medicare-and-medigap-coverage-.
23 Commonwealth of Massachusetts General Laws Part I Title XXII Chapter 176K: Medicare Supplement Insurance
Plans, at https://malegislature.gov/Laws/GeneralLaws/PartI/TitleXXII/Chapter176K.
24 Medicare.gov, “Medigap in Minnesota,” at https://www.medicare.gov/supplements-other-insurance/how-to-
compare-medigap-policies/medigap-in-minnesota.
25 Minnesota Department of Commerce, “Medicare,” at https://mn.gov/commerce/insurance/health/basics/medicare/.
See the “Supplement Policies” section.
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• Wisconsin’s Medigap state plans are either the “Basic Plan” or plans known as
“50% and 25% Cost-sharing Plans,” which are similar to federally standardized
Plans K and L. A high-deductible plan is also available.26 In addition to the
federal standards, these plans cover state-mandated benefits such as skilled
nursing facilities care and home health care. The Wisconsin Office of the
Commissioner of Insurance approves policies and provides lists of insurers.27
Table 1 lists Medigap standardized benefit plans by identifying letter and the covered benefits of
each plan.
Table 1. Medicare Supplement Insurance (Medigap) Standardized Plans, 2023
(benefit coverage by plan letter)

Plana
Benefits
A
B
Cb
D
Fbc
Gd
K
L
M
N
Part A
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Coinsurance
and Hospital
Costse
Part B
Yes
Yes
Yes
Yes
Yes
Yes
50%
75%
Yes
Yesf
Coinsurance
or
Copayment
Blood (first 3
Yes
Yes
Yes
Yes
Yes
Yes
50%
75%
Yes
Yes
pints)
Part A
Yes
Yes
Yes
Yes
Yes
Yes
50%
75%
Yes
Yes
Hospice Care
Coinsurance
or
Copayment
Skil ed
No
No
Yes
Yes
Yes
Yes
50%
75%
Yes
Yes
Nursing
Facility Care
Coinsurance
Part A
No
Yes
Yes
Yes
Yes
Yes
50%
75%
50%
Yes
Deductible
Part B
No
No
Yes
No
Yes
No
No
No
No
No
Deductible
Part B Excess No
No
No
No
Yes
Yes
No
No
No
No
Charges
Foreign
No
No
80%
80%
80%
80%
No
No
80%
80%
Travel
Emergency
(up to plan
limits)

26 Medicare.gov, “Medigap in Wisconsin,” at https://www.medicare.gov/supplements-other-insurance/how-to-
compare-medigap-policies/medigap-in-wisconsin.
27 Wisconsin Office of the Commissioner of Insurance, “Medicare Supplement Insurance Policies List 2023,” at
https://oci.wi.gov/Documents/Consumers/PI-010.pdf.
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Plana
Benefits
A
B
Cb
D
Fbc
Gd
K
L
M
N
Out-of-
N/A
N/A
N/A
N/A
N/A
N/A
$6,940 $3,470 N/A
N/A
pocket limitg
in
in
2023
2023
Source: Based on the “Compare Medigap Plans” table (CMS, https://www.medicare.gov/supplements-other-
insurance/how-to-compare-medigap-policies); Chart 3.3 Covered benefits and enrol ment in standardized
Medigap Plans, 2020 (MedPAC, https://www.medpac.gov/wp-content/uploads/2022/07/
July2022_MedPAC_DataBook_SEC_v2.pdf#page=38) and Appendix A of The State of Medicare Supplement
Coverage (AHIP, https://ahiporg-production.s3.amazonaws.com/documents/202301-AHIP_MedicareSuppCvg-
v03.pdf#page=17).
Notes: This table reflects the benefit design for Medicare Supplement plans under P.L. 114-10.
a. Discontinued plans (E, H, I, and J) are not included in this table. These plans are no longer sold to new
enrol ees, but if an insurer stil offers a discontinued plan, enrol ees can renew the policy.
b. Beginning in 2020, new policies for Plans C or F (or F with a high deductible) are not allowed to be sold.
However, beneficiaries who purchased Plans C or F before 2020 are to be able to continue to purchase
those plans in subsequent plan coverage years.
c. Plan F also offers a high-deductible plan in some states. If the enrol ee chooses this option, the enrol ee
must pay Medicare-covered costs up to the deductible amount of $2,700 in 2023 before the Medicare
Supplement plan pays anything.
d. Plan G offers a high-deductible plan in some states for those enrol ees newly eligible after January 1, 2020.
e. Provides coverage for hospital costs up to an additional 365 days after Medicare benefits are used up.
f.
Plan N pays 100% of the Part B coinsurance, except for a copayment of up to $20 for some office visits and
up to a $50 copayment for emergency room visits that do not result in an inpatient admission.
g. For Plans K and L, after an enrol ee has met the out-of-pocket yearly limit and the yearly Part B deductible,
the Medicare Supplement plan pays 100% of covered services for the rest of the year.
Data and Sources
Medigap enrollment is tracked by multiple agencies or institutions. Available information
regarding Medigap enrollment trends is accessible through the sources outlined below.
Centers for Medicare & Medicaid Services
The Centers for Medicare & Medicaid Services (CMS) is the operating division within HHS that
administers the Medicare program. CMS does not directly track Medigap enrollment because
these plans are private options and not a part of the federal Medicare program. The Medicare
Current Beneficiary Survey (MCBS),28 a representative survey conducted by CMS, contains some
questions regarding supplemental coverage, including Medigap. However, these data (from the
Community Survey component of the MCBS) do not include information on beneficiaries
residing in institutional settings, such as long-term-care nursing homes. MCBS does not gather
information on specific types of Medigap plans.

28 See “Medicare Current Beneficiary Survey (MCBS)” at https://www.cms.gov/research-statistics-data-and-systems/
research/mcbs.
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National Association of Insurance Commissioners and America’s
Health Insurance Plans
NAIC, an association of the insurance commissioners of the states and territories, collects
financial and enrollment infornamation from insurance companies based on state requirements.
NAIC does not directly make this information publicly available. AHIP29, a trade group for health
insurers, uses NAIC data to publish an annual report outlining Medigap enrollment trends at the
national and state levels.30 California’s data are not fully represented by NAIC, but AHIP gathers
this information through the California Department of Managed Health Care (DMHC)31 and
combines NAIC and DMHC data to determine the national Medigap enrollment. Additionally,
AHIP uses MCBS data to provide demographic information about Medigap enrollees.
Medicare Payment Advisory Commission
The Medicare Payment Advisory Commission (MedPAC) is a nonpartisan independent legislative
branch agency that provides the U.S. Congress with analysis and policy advice on the Medicare
program. MedPAC’s annual Data Book includes basic Medigap enrollment and benefits
information within its “supplemental coverage” section,32 based on MCBS and NAIC data.
MedPAC reports overall enrollment in Medicare supplemental coverage products based on
MCBS data, which exclude those in long-term care institutions.
MedPAC has also issued reports that discuss or analyze Medigap and other supplemental health
coverage.33
Enrollment and Trends
CRS provides selected enrollment data based primarily on the data sources outlined above. More
information on state-level enrollments and beneficiary demographics are available in the AHIP
and MedPAC sources. The data presented below align with the most recent years available from
each source.
Statistics come from different sources, and not all Medicare beneficiaries are eligible to enroll in
Medigap. Some sources provide the share of Medigap enrollees as a percentage of “Original
Medicare” (Parts A and/or B) enrollment. However, this does not take into account those in
original Medicare who may not be eligible to enroll in Medigap due to their
• eligibility status (disabled beneficiaries under age 65 do not have a federally
guaranteed right to enroll);
• Part B enrollment status (not all Original Medicare enrollees have Part B); or

29 Formerly known as America’s Health Insurance Plans.
30 America’s Health Insurance Plans (AHIP), “The State of Medicare Supplement Coverage: Trends in Enrollment and
Demographics,” February 2023, at https://www.ahip.org/resources/the-state-of-medicare-supplement-coverage-2.
31 California Department of Managed Health Care, “Financial Summary Data” at https://www.dmhc.ca.gov/
DataResearch/FinancialSummaryData.aspx.
32 For Medigap information, see MedPAC July 2022 Data Book, pp. 25-27, at https://www.medpac.gov/wp-content/
uploads/2022/07/July2022_MedPAC_DataBook_SEC_v2.pdf#page=26.
33 Such as “Exploring the Effects of Secondary Coverage on Medicare Spending for the Elderly,” Direct Research LLC
for MedPAC, 2014, at https://www.medpac.gov/wp-content/uploads/import_data/scrape_files/docs/default-source/
contractor-reports/august2014_secondaryinsurance_contractor.pdf.
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• decision not to enroll during open enrollment (there is no federal guaranteed-
issue right after open enrollment).
Because the Medicare and Medigap enrollment data are compiled from different sources, these
numbers are not directly comparable. As explained above, not every Medicare beneficiary is
eligible to enroll in Medigap.
Medicare Enrollment
Table 2 provides total Medicare enrollment during 2017-2021, with breakdowns by eligibility
status (aged/disabled), and coverage type (Original Medicare or Medicare Advantage).
Table 2. Medicare Enrollment by Coverage Type and Eligibility (Aged/Disabled),
2017-2021
Medicare Enrollment
2017
2018
2019
2020
2021
Total Beneficiaries
58,457,244
59,989,883
61,514,510
62,840,267
63,892,626
Eligibility Status
Aged Beneficiaries
49,678,033
51,303,898
52,991,455
54,531,919
55,851,321
Disabled Beneficiaries
8,779,211
8,685,985
8,523,055
8,308,348
8,041,304
Coverage Type
Original Medicare
38,667,830
38,665,082
38,577,012
37,776,345
36,356,380
Beneficiariesa
Medicare Advantage and
19,789,414
21,324,800
22,937,498
25,063,922
27,536,246
Other Beneficiariesb
Source: Medicare Monthly Enrol ment Dataset, CMS, https://data.cms.gov/summary-statistics-on-beneficiary-
enrol ment/medicare-and-medicaid-reports/medicare-monthly-enrol ment.
Notes: Data extracted by CRS for yearly totals 2017-2021.
a. “Original Medicare” refers to fee-for-service Parts A and/or B. Only individuals enrol ed in Original
Medicare can purchase Medigap plans.
b. From the dataset definitions: “Count of all Medicare Advantage and Other Health Plan beneficiaries.”
Medigap Enrollment
Table 3 provides total national Medigap enrollment, while Table 4 highlights enrollment by plan
type, but does not include California enrollees. For demographic information on Medigap
enrollees, including age, income, eligibility status, and health status, see Table 5.
Table 3. National Medicare Supplement Insurance (Medigap) Enrollment, 2017-2021
Medigap Enrollment
2017
2018
2019
2020
2021
Reported to NAIC
13,059,201
13,546,429
14,013,086
13,900,107
14,077,889
Reported to California
435,259
444,391
469,792
495,681
514,179
DMHC
Total
13,494,460
13,990,820
14,482,878
14,395,788 14,592,068
Source: The State of Medicare Supplement Coverage: Trends in Enrol ment and Demographics, AHIP, 2023
https://www.ahip.org/documents/202301-AHIP_MedicareSuppCvg-v03.pdf#page=3.
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Note: AHIP Center for Policy and Research analyzed NAIC Medicare Supplement Insurance Experience Exhibits
and the California DMHC Enrol ment Summary Reports to produce these enrol ment statistics.
Medigap Enrollment by Plan Type
As described in the “Plan Types and Benefits” section, Medigap plans must conform to uniform
benefit packages, known as standardized plans. However, waivered states (Massachusetts,
Minnesota, and Wisconsin) offer their own standardized plans, which are exempt from the federal
standardization requirements. Waivered state plans vary; states may offer one or multiple
waivered plans, and there may be state versions of the federally standardized plans, with
additional state-required benefits required. Some pre-standardized plans are still held by
beneficiaries who originally enrolled before the standardization requirements took effect.
Table 4 lists Medigap enrollment by plan type, including waivered state plans and pre-
standardized plans. California enrollees are not included in Table 4 due to differences in reporting
requirements and available data. State-level data (except for California) are available through the
AHIP report.
Table 4. Medicare Supplement Insurance Enrollment by Plan Type, 2018-2021
(California enrollees not included)
Plan Type
2018
2019
2020
2021
A
120,514
107,919
99,809
92,828
B
227,256
206,587
182,388
181,741
C
700,552
624,321
542,229
478,702
D
146,347
123,117
125,899
151,327
E
58,229
51,203
45,485
38,371
F
7,043,167
6,804,076
6,238,576
5,749,712
G
2,305,925
3,067,424
3,727,474
4,513,504
H
33,299
31,014
27,259
21,891
I
72,217
74,338
56,501
46,350
J
407,964
371,432
332,461
300,074
K
82,202
80,527
76,331
69,866
L
47,858
42,546
38,949
33,648
M
4,403
4,151
3,782
4,546
N
1,342,350
1,359,949
1,362,694
1,384,304
Waivered State Plans
714,930
857,757
849,518
840,834
Pre-Standardized Plans
239,216
206,725
190,752
170,191
Total
13,546,429
14,013,086
13,900,107
14,077,889
Source: The State of Medicare Supplement Coverage: Trends in Enrol ment and Demographics, AHIP, 2023
https://www.ahip.org/documents/202301-AHIP_MedicareSuppCvg-v03.pdf#page=9.
Notes: AHIP Center for Policy and Research analyzed NAIC Medicare Supplement Insurance Experience
Exhibits. AHIP states, “The enrol ment data for this Figure do not include Medicare Supplement enrol ment
numbers reported by insurance providers in 2018- 2021 to the California DMHC. The data for standardized
policies include Medicare SELECT plans and those issued in 3 states (MA, MN, and WI) that received waivers
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from the standardized product provisions of OBRA 1990.” Total Medigap enrol ment, including for California, is
included in Table 3.
Demographics of Medigap Enrollees
Data on certain demographic characteristics of Medigap enrollees are available only through the
MCBS, with the most recent data available from 2019. Both the MedPAC Data Book and the
AHIP report provide demographic analyses. Table 5 replicates MedPAC’s analysis of MCBS data
on sources of supplemental coverage among noninstitutionalized Medicare beneficiaries. See the
AHIP report for additional breakdowns.
Table 5. Sources of Supplemental Coverage Among Noninstitutionalized Medicare
Beneficiaries, by Beneficiary Characteristics, 2019
Employer-
Medicare
Other
Beneficiaries
Sponsored
Medigap
Managed
Public
Medicare

(Thousands)
Insurance
Insurance Medicaid
Care
Sector
Only
All
Beneficiaries
50,097
18%
22%
9%
41%
0%
10%
Age
<65
6,799
9
3
34
38
0
16
65–69
11,082
16
26
5
41
0
12
70–74
12,493
19
26
5
41
0
9
75–79
9,004
20
24
4
43
0
8
80–84
5,515
22
23
5
43
0
7
85+
5,203
21
25
5
40
0
8
Income-to-Poverty Ratio
≤1.00
7,751
3
6
38
44
0
9
1.00 to 1.20
3,156
3
9
23
52
0
13
1.20 to 1.35
1,973
6
17
12
43
1
21
1.35 to 2.00
8,095
11
21
5
48
1
14
>2.00
29,121
26
28
0
37
0
8
Eligibility Status
Aged
43,076
19
25
5
41
0
9
Disabled
6,712
9
3
33
39
0
16
ESRD
309
20
19
23
29
1
8
Residence
Urban
40,469
17
21
8
44
0
9
Rural
9,628
18
27
12
28
0
14
Sex
Male
22,465
18
21
8
40
0
12
Female
27,632
17
23
9
42
0
9
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Medigap: Background and Statistics

Employer-
Medicare
Other
Beneficiaries
Sponsored
Medigap
Managed
Public
Medicare

(Thousands)
Insurance
Insurance Medicaid
Care
Sector
Only
Health Status
Excellent/
23,630
20
27
4
40
0
9
Very Good
Good/Fair
23,415
16
19
12
42
0
11
Poor
2,846
12
12
24
39
0
13
Source: MedPAC Databook 2022 Chart 3-2, based on MedPAC analysis of MCBS Survey File 2019,
https://www.medpac.gov/wp-content/uploads/2022/07/July2022_MedPAC_DataBook_SEC_v2.pdf#page=37.
Notes: MedPAC notes, “We assigned beneficiaries to the supplemental coverage category in which they spent
the most time in 2019. They could have had coverage in other categories during 2019. ‘Medicare managed care’
includes Medicare Advantage, cost, and health care prepayment plans. ‘Other public sector’ includes federal and
state programs not included in other categories. ‘Urban’ indicates beneficiaries living in metropolitan statistical
areas (MSAs) as indicated by core-based statistical areas. ‘Rural’ indicates beneficiaries living outside MSAs, which
includes both micropolitan statistical areas and rural areas as indicated by core-based statistical areas. Analysis
excludes beneficiaries living in institutions such as nursing homes. Analysis also excludes beneficiaries who were
not in both Part A and Part B throughout their Medicare enrol ment in 2019 or who had Medicare as a
secondary payer. The number of beneficiaries differs among boldface categories because we excluded
beneficiaries with missing values. Numbers in some rows do not sum to 100 percent because of rounding. The
Medicare Current Beneficiary Survey is col ected from a sample of Medicare beneficiaries; year-to-year variation
in some reported data is expected.”

Author Information

Michele L. Malloy

Research Librarian

Acknowledgments
Bernadette Fernandez co-authored a previous version of this product.
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Medigap: Background and Statistics

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