South Dakota Medicare Supplement Plans: Open Enrollment, Under 65

A South Dakota Medicare Supplement insurer can't turn you down or charge more for your health if you apply before or during the six months that start when you're 65 and in Part B.1 South Dakota's rules for Medicare Supplement plans also give people who have Medicare because of a disability, at any age, a six-month open enrollment into any policy after they enroll in Medicare Part B, something federal law generally doesn't require.1

In This Guide

• Can you buy Medigap under 65 in South Dakota?
• Can you apply early for South Dakota Medigap open enrollment?
• How does prior coverage shorten a South Dakota pre-existing condition wait?
• When does South Dakota Medigap guaranteed issue apply after a coverage loss?
• Which Medicare Supplement plans can you buy in South Dakota?
• Should you pick Medigap or Medicare Advantage?
• What protections come with a South Dakota Medicare Supplement plan after you buy?
• How do the South Dakota Medigap windows compare?
• Where can South Dakotans get Medigap help?
• Frequently Asked Questions
• Learn More

Can you buy Medigap under 65 in South Dakota?

Yes: South Dakota's rule ARSD 20:06:13:84 (Administrative Rules of South Dakota) entitles a person under 65 who has Medicare because of a disability to open enrollment into any Medigap policy if they apply within six months of enrolling in Part B, but only if they became eligible for Medicare on or after July 1, 1999. South Dakota's Medigap open-enrollment rule, ARSD 20:06:13:84, covers any individual, regardless of age, who becomes eligible for Medicare by reason of age or disability, as long as they apply for the Medigap policy within six months of enrolling in Part B.1

The South Dakota Division of Insurance puts it this way on its Medicare Supplement Policies page: for people under 65 who qualify for Medicare by reason of disability, "there is also a six month open enrollment period beginning on the date of enrollment in Part B Medicare."1

How the South Dakota age-75 rate ceiling works

ARSD 20:06:13:84 lets a Medigap carrier rate people who qualify for Medicare by disability as a separate class, but only if two conditions hold:1

• the disability-class rate is actuarially justified; and
• the disability-class rate does not exceed the rate the carrier charges an individual who qualifies for Medicare by age and is 75 years old.

Brevy's guide to how Medigap premiums are priced explains the rating methods carriers use.

Why the South Dakota under-65 right stands out

The Centers for Medicare & Medicaid Services (CMS) guide Choosing a Medigap Policy states that federal law generally doesn't require insurance companies to sell Medigap policies to people under 65. The same CMS guide lists South Dakota among the states that, at the time of printing, require insurance companies to offer at least one kind of Medigap policy to people with Medicare under 65.1

Turning 65 opens a second window. CMS states that a person who already has Medicare Part B will still get a Medigap Open Enrollment Period on turning 65, so a South Dakotan who bought a disability-rated policy at 58 gets the age-65 open enrollment protections of South Dakota Codified Laws (SDCL) 58-17A-17 again at 65.1

Can you apply early for South Dakota Medigap open enrollment?

Yes. South Dakota's Medigap open enrollment statute, SDCL 58-17A-17, protects an application submitted before the six-month window opens as well as during it. Under SDCL 58-17A-17, no issuer may deny, condition, or price a Medicare supplement policy sold in South Dakota based on an applicant's health status, claims experience, receipt of health care, or medical condition if the application is submitted "prior to or during" the six-month period beginning with the first day of the month in which the person is 65 or older and enrolled in Part B.1

Two more parts of SDCL 58-17A-17 matter to a buyer:1

• Every policy, not just one: each Medicare supplement policy an issuer currently offers must be made available to every applicant who qualifies under the South Dakota statute, without regard to age.
• The clock follows Part B: a South Dakotan who turns 65 but delays Part B has an open enrollment window that starts only in the first month they are both 65 or older and enrolled in Part B.

The South Dakota Division of Insurance summarizes the rule on the same Medicare Supplement Policies page: during the six-month open enrollment period after reaching 65, Medicare supplement insurance "can be obtained regardless of your health condition."1

The same six-month floor exists nationwide. Section 1882 of the Social Security Act bars health-based denial or pricing for anyone whose Medigap application is submitted before or during the six months beginning with the first month they are 65 or older and enrolled in Part B.2 Medicare's March 2026 guide Choosing a Medigap Policy calls the Medigap Open Enrollment Period "a one-time enrollment period; it doesn't repeat every year."1 Brevy's guide to the Medigap open enrollment period covers the federal window in more depth.

How does prior coverage shorten a South Dakota pre-existing condition wait?

Prior creditable coverage shortens or removes the wait, but a South Dakota Medigap policy can have one. SDCL 58-17A-17 still lets a South Dakota Medigap policy exclude benefits during its first six months for a pre-existing condition that was treated or diagnosed during the six months before the policy took effect.1

Under the South Dakota administrative rule ARSD 20:06:13:83, an open enrollment applicant's prior creditable coverage works like this:1

• Six months or more of continuous creditable coverage: the South Dakota Medigap issuer may not exclude benefits for a pre-existing condition.
• Less than six months: the South Dakota Medigap issuer must shorten any pre-existing condition exclusion by the total of the applicant's creditable coverage.

Medicare's Choosing a Medigap Policy guide adds the federal gap test: other health coverage counts toward creditable coverage only if the break in coverage was no more than 63 days.1 A South Dakotan moving from employer coverage to Medigap should ask the insurer in writing how it counted the months before signing. Brevy's guide to Medigap and pre-existing conditions explains the waiting period nationally.

When does South Dakota Medigap guaranteed issue apply after a coverage loss?

South Dakota's guaranteed issue rules are in ARSD chapter 20:06:13. For an eligible person, ARSD 20:06:13:79 says a Medigap insurer may not deny or condition a Medigap policy described in ARSD 20:06:13:81 that it offers to new enrollees, may not price it based on health status, claims experience, receipt of health care, or medical condition, and may not impose a pre-existing condition exclusion.1

The South Dakota guaranteed issue right covers only certain Medigap policies, not every plan letter, so check Brevy's national guide to Medigap guaranteed issue rights and ask the insurer which policies your situation opens.

Situations the South Dakota rule includes

Under ARSD 20:06:13:80, the people eligible for South Dakota guaranteed issue include those in these situations:1

• Employer coverage ends: you are covered by an employee welfare benefit plan or an employer-based health plan, and that coverage terminates.
• A Medicare Advantage or PACE plan ends or leaves: the Medicare Advantage plan's certification is terminated, the plan stops serving your area, you are no longer eligible because you moved or your circumstances changed, or the organization substantially violated its contract or materially misrepresented the plan in marketing. A person 65 or older enrolled with a Program of All-Inclusive Care for the Elderly (PACE) provider is covered under the same terms.
• Your Medigap insurer fails or misleads you: your Medigap coverage ends because of the insurer's insolvency or bankruptcy or another involuntary termination, or the insurer substantially violated the policy or materially misrepresented it in marketing.
• A first-time switch ends within 12 months: you dropped a Medigap policy to enroll for the first time in a Medicare Advantage plan, a Medicare cost plan, a similar demonstration, a PACE provider, or a Medicare SELECT policy, then ended that enrollment within the first 12 months.
• A plan chosen at 65 ends within 12 months: on first becoming eligible for Part A at 65, you enrolled in a Medicare Advantage plan or with a PACE provider and left no later than 12 months after the enrollment took effect.

ARSD 20:06:13:80 also requires the applicant to submit evidence of the date of termination, disenrollment, or Part D enrollment with the Medigap application.1 Under ARSD 20:06:13:82, the organization, insurer, or plan administrator whose termination ends your coverage must send a notice of your guaranteed issue rights along with the notice of termination.1

How long South Dakota's guaranteed issue windows last

ARSD 20:06:13:80.01 sets the South Dakota guaranteed issue period for each case:1

• Employer plan ends: the window closes 63 days after the later of the termination notice (or, with no notice, a claim denial caused by the termination) or the date the coverage ends.
• Involuntary loss of a Medicare Advantage, cost plan, trial, or first-at-65 plan: the window opens on the date you receive the termination notice and closes 63 days after the coverage ends.
• Voluntary disenrollment in the listed situations: the window opens 60 days before the disenrollment takes effect and closes 63 days after that date.

The 60-day early start lets a South Dakotan who is leaving a plan voluntarily apply for Medigap before the old coverage ends. Missing a window matters, because outside open enrollment an insurance company is allowed to deny a Medigap policy to someone who doesn't meet its medical underwriting requirements.2

Which Medicare Supplement plans can you buy in South Dakota?

Medigap plans are standardized by letter. Medicare's 2026 Choosing a Medigap Policy guide charts the Medigap plans as A, B, C, D, F, G, K, L, M and N, and states that every insurance company selling Medigap must offer at least Plan A.1

Medigap Plans C and F are closed to people new to Medicare. CMS states that Medigap plans sold to people new to Medicare on or after January 1, 2020 can't cover the Part B deductible, so people new to Medicare since that date have the right to buy Plans D and G instead. A person counts as new to Medicare for this rule if they turned 65 on or after January 1, 2020 and got Medicare Part A on or after January 1, 2020.1

The South Dakota Division of Insurance describes Medicare Select as "a managed care version of Medicare supplement insurance" that requires the use of network hospitals and restricts payment to non-network hospitals except in an emergency.1 The Division's Medicare Supplement Policies page also links to its list of Medicare Supplement Companies.1

Brevy's guides to how the lettered Medigap plans work and to Medigap Plan G vs. Plan N compare the letters benefit by benefit.

Should you pick Medigap or Medicare Advantage?

The two don't combine. The CMS booklet Understanding Medicare Advantage Plans says you can't use Medigap to pay Medicare Advantage Plan copayments, coinsurance, deductibles, or premiums.3 The same CMS booklet says it's illegal for anyone to sell you a Medigap policy while you're in a Medicare Advantage Plan unless you're switching back to Original Medicare, and tells readers to report such a sales attempt to the State Insurance Department.3 Brevy's guide to illegal Medigap sales walks through that federal rule.

Leaving Medigap for Medicare Advantage can be hard to reverse. CMS states that in most cases, if you drop a Medigap policy to join a Medicare Advantage Plan, you may not be able to get the same policy back.3

The federal "trial right" softens that risk. CMS states that a person who joins a Medicare Advantage Plan for the first time and isn't happy with it can buy a Medigap policy on returning to Original Medicare within 12 months of joining.3 South Dakota's version of the trial right appears in the guaranteed issue situations above. Brevy's comparison of Original Medicare and Medicare Advantage sets the two side by side.

What protections come with a South Dakota Medicare Supplement plan after you buy?

South Dakota's rules protect a Medigap policyholder in two ways:1

• Renewal: under ARSD 20:06:13:19, a South Dakota Medigap insurer may not reserve the right not to renew a policy, and may not cancel or refuse to renew a guaranteed renewable policy solely because your health has deteriorated.
• Right of return: under ARSD 20:06:13:31.03, a South Dakota Medigap policy must tell you that you can return it within 30 days after delivery and have the premium refunded if you're not satisfied for any reason.

Medicare's Choosing a Medigap Policy guide adds that any new Medigap policy issued since 1992 is guaranteed renewable even if you have health problems.1

Switching carries its own rules. Medicare.gov states that in most cases you won't be able to switch Medigap policies outside your six-month Medigap Open Enrollment Period unless you have a guaranteed issue right, and that switching outside it may mean paying more and answering medical questions.4 Under Section 1882(s)(2)(C) of the Social Security Act, a Medigap policy that replaces one in effect for six months or longer may not impose a new pre-existing condition or waiting period for similar benefits.4

How do the South Dakota Medigap windows compare?

Sources for the table: SDCL 58-17A-17, ARSD 20:06:13:79 through 20:06:13:84, and Medicare's Choosing a Medigap Policy guide.1

Where can South Dakotans get Medigap help?

The South Dakota Division of Insurance, part of the Department of Labor & Regulation, publishes the state's Medigap guidance on its Medicare Supplement Policies page. The South Dakota Division of Insurance can be reached at 605.773.3563 (TTY via 711), by email at sdinsurance@state.sd.us, or at 124 South Euclid Avenue, 2nd Floor, Pierre, SD 57501.1

South Dakota's State Health Insurance Assistance Program (SHIP) is Senior Health Information and Insurance Education (SHIINE). The CMS contacts directory lists SHIINE as the SHIP covering South Dakota and describes its service as personalized health insurance counseling.5 Medicare's Choosing a Medigap Policy guide says to visit shiphelp.org to get the number for your local SHIP.1

For questions about Original Medicare itself, 1-800-MEDICARE (1-800-633-4227) is the official Medicare line run by CMS, and TTY users call 1-877-486-2048.6 Brevy's South Dakota Medicare hub covers the state's other Medicare options, and Brevy's guide to South Dakota Medicare Savings Programs covers help with Medicare costs.

Learn More

Find personalized help timing a South Dakota Medigap application inside your open enrollment or guaranteed issue window at brevy.com.

The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.