New Mexico · How we compare plans

Can I Switch From Medicare Advantage to Medigap? New Mexico Rules for 2027

Yes — but it is two decisions, not one. Leaving Medicare Advantage is governed by enrollment windows; getting a Medigap company to accept you is governed by a different set of rules, and for most people past 65 the answer to the second question is "only if they agree." Here is who has a right in New Mexico this year, what a company can do when you do not, and the order we do it in.

By the New Mexico Medicare Help Data Desk

Reviewed by Brian Penner, Independent Medicare advisor — no pressure · Published October 5, 2026

Yes, you can switch from Medicare Advantage to a Medigap policy — but the question hides two separate ones. Leaving a Medicare Advantage plan is a Medicare rule: Medicare.gov allows it during the Open Enrollment Period of October 15, 2026 – December 7, 2026, with Original Medicare starting January 1, 2027; during the Medicare Advantage Open Enrollment Period of January 1, 2027 – March 31, 2027, when you may "drop your Medicare Advantage Plan and return to Original Medicare" and "join a separate Medicare drug plan," effective the first of the next month; or during a Special Enrollment Period, such as your plan being discontinued (Medicare.gov). Buying Medigap is an insurance-company decision: a company has to accept you only during "the 6-month period that starts the first day of the month you're 65 or older and signed up for Part B," or when a federal guaranteed-issue right applies. Outside those, Medicare.gov is blunt: "there's no federal guarantee that an insurance company will sell you a Medigap policy. If you're able to buy one, it may cost more due to past or present health problems" (Medicare.gov). In New Mexico for 2027, the people with a right are those whose plan is ending, those in their first year of trying Advantage, and those still inside their six months. Everyone else is asking permission.

Sources: Medicare.gov — Joining a plan; Medicare.gov — When can I buy a Medigap policy?; CMS — Choosing a Medigap Policy, pp. 17–19.

Why is this two questions, not one?

Because Medicare runs one half and private insurers run the other. Medicare Advantage is a Medicare program with enrollment periods set in federal regulation; you leave it by enrolling in something else or by disenrolling, and Medicare processes the change. A Medigap policy is a private insurance contract that pays Original Medicare's deductibles and 20% coinsurance. Congress required companies to sell it without health questions in a few defined situations — the six months after you get Part B at 65, and a list of guaranteed-issue events — and left everything else to the company and to state law. The confusion comes from the fact that the two halves usually line up: during your first months on Medicare, both doors are open. Later, the Medicare door still opens every autumn, and the Medigap door may not.

CMS's own guide warns about exactly this when people go the other way: "if you drop your Medigap policy to join a Medicare Advantage Plan, you may not be able to get the same policy back (or in some cases any Medigap policy) unless you leave your Medicare Advantage Plan during your trial period" (Choosing a Medigap Policy, p. 28). The same logic applies to anyone who chose Advantage at 65 and, years later, wants the predictability of Medigap.

When can I leave a Medicare Advantage plan?

• October 15, 2026 – December 7, 2026. Anyone may "switch from a Medicare Advantage Plan to Original Medicare"; the change takes effect January 1, 2027, and "the plan must get your request to join by December 7" (Medicare.gov).
• January 1, 2027 – March 31, 2027. If you are in an Advantage plan on January 1 you may make one change: switch Advantage plans, or "drop your Medicare Advantage Plan and return to Original Medicare" and "join a separate Medicare drug plan." Coverage "starts the first of the month after the plan gets your request." CMS's fact sheet on enrollment periods adds: "You can only make one change each year during the Medicare Advantage Open Enrollment Period" (CMS Product 11219).
• Special Enrollment Periods. Moving, losing other coverage, and a plan that is discontinued — which gives members a window from December 8 through February 28, 2027 (42 CFR § 422.62(b)(1)). A plan that ends December 31 does not need to be left at all; it ends on its own, and on January 1 you are in Original Medicare unless you chose something else. What happens if you do nothing covers that default.

One practical point: you do not have to "cancel" an Advantage plan to return to Original Medicare during these windows. Enrolling in a stand-alone drug plan is itself a disenrollment from an Advantage plan that includes drug coverage, and a written disenrollment request to the plan does the same. Do I need to cancel my plan? explains the mechanics.

Do I have a right to buy Medigap, or just permission to apply?

A right means the company must sell you the policy the right covers, at the price it charges anyone your age, with no health questions. Permission means you may fill in an application and the company may say yes, yes-at-a-higher-rate, or no. Federal law provides rights in three places that matter here (Medicare.gov; CMS, pp. 17–18):

1. Your Medigap Open Enrollment Period — six months from the first month you are both 65 or older and enrolled in Part B. It happens once. Someone who took Part B at 65 in May 2026 has it until the end of October 2026 regardless of being in an Advantage plan now.
2. Your plan is leaving Medicare or your area. You may buy Plan A, B, D, G, K or L — C or F if you were eligible for Medicare before 2020 — applying "as early as 60 calendar days before the date your coverage will end" and "no later than 63 calendar days after." For a December 31, 2026 end date that is November 1, 2026 to March 4, 2027. This is the Presbyterian, CHRISTUS and Blue Cross situation; our guaranteed-issue post has the proof the company will ask for.
3. The two trial rights. First: you "joined a Medicare Advantage Plan … when you were first eligible for Medicare Part A at 65, and within the first year of joining, you decide you want to switch to Original Medicare" — you may buy "any Medigap policy that's sold by an insurance company in your state." Second: you "dropped a Medigap policy to join a Medicare Advantage Plan … for the first time, you've been in the plan less than a year, and you want to repurchase the Medigap policy" — you get the old policy back if the company still sells it, otherwise Plan A, B, C*, D*, F* or G*. Both: apply 60 days before to 63 days after the Advantage coverage ends, and CMS notes "your rights may last for an extra 12 months under certain circumstances" (p. 18). Turned 65 in 2026 and chose Presbyterian? works through the first one.

Missing from that list, deliberately: "my premiums went up," "my doctor left the network," "I am unhappy with prior authorizations," and "I have been in Advantage for five years and want out." Those are the most common reasons people ask the question, and none of them is a federal right. They are permission to apply.

Which door am I at? Six situations

Sources: Medicare.gov — Joining a plan; Medicare.gov — When can I buy a Medigap policy?; CMS — Choosing a Medigap Policy, pp. 17–19; 42 CFR § 422.62; KFF, 2018 (under-65 rules). Plans C and F: only if you were eligible for Medicare before January 1, 2020.

Two notes on the table. The under-65 row is the hardest one in New Mexico: KFF's state survey found that "under federal law, Medigap insurers are not required to sell Medigap policies to the over 9 million Medicare beneficiaries who are under age of 65," and that 31 states require at least one kind of policy be offered to them (KFF, July 2018). CMS adds that "some people may have additional rights under their state's law" and tells you to "call your State Insurance Department or local SHIP" (p. 19) — in New Mexico, SHIP is at 1-800-432-2080. And the plan-ending row is a genuine exception to the usual pessimism: a non-renewal is the one event that gives a long-time Advantage member of any health a clean path to Medigap, which is why it belongs in the comparison for every Presbyterian, CHRISTUS and Blue Cross member this autumn, not only the ones who were already thinking about it.

What can a Medigap company do if I have no right?

Three things, and CMS names all of them. "You may have to pay more for your new Medigap policy and answer some medical questions if you're buying a Medigap policy outside of your Medigap Open Enrollment Period" (p. 27). The company "may refuse to sell a policy to an applicant with certain medical conditions" (KFF). And for a policy it does issue, "you may have to wait up to 6 months before any new benefits or your pre-existing condition will be covered" (Medicare.gov).

Sources: Medicare.gov — When can I buy a Medigap policy?; Medicare.gov — Can I switch or drop my Medigap policy?; CMS — Choosing a Medigap Policy, pp. 10–11, 17–18, 26–27; NM Senate Bill 21.

What underwriting looks like in practice: an application with health questions — diagnoses, hospital stays, medications, planned procedures — and the company's own underwriting guide deciding which answers mean yes, yes at a higher rate class, or no. Each company's questions and limits are its own, which is why one company's no is not every company's no, and why the application goes in before any change to the Advantage plan. If the policy is declined, nothing has changed; if it is approved, it is dated for the first of the month your Advantage coverage ends. Nationally, KFF's reading is that this is the position of 90% of Advantage members 65 and older, 22.4 million people, and that in underwriting states "Medicare Advantage enrollees with pre-existing conditions may find it too financially risky to switch to traditional Medicare if they are unable to purchase a Medigap policy" (KFF, October 2024).

What does New Mexico add — and not add?

New Mexico has not added a guaranteed-issue right for people leaving Medicare Advantage, and it is not one of the 4 states — Connecticut, Massachusetts, Maine and New York — that KFF lists as requiring companies to accept every applicant 65 and older continuously or once a year (KFF). What the state did add, in Senate Bill 21 of 2026, is a birthday rule for people who already hold Medigap: from January 1, 2027, an "eligible policyholder" — a Part A or B beneficiary "sixty-five years of age or older" with a Medigap policy — gets a window that "shall commence with the first day of the eligible policyholder's birthday month and remain open for at least sixty days thereafter" to move to "any medicare supplement policy of an equal or lesser value" at any company, and the issuer "shall not deny, delay or condition the issuance" on health (SB 21, final text). The ALTSD analysis counted 71,380 Medigap policyholders in the state as of September 2024 (nmlegis.gov).

So the birthday rule changes the second decision for people who get through the door once: a Medigap policy bought in New Mexico in 2027 — through a guaranteed-issue right, a trial right, the six-month period, or underwriting — can be moved to an equal-or-lesser policy at another company every year without health questions thereafter. Can I switch Medigap plans when my premium goes up? covers that rule in full, including the 2027 window dates by birthday month. It does not change the first decision. An Advantage member with no federal right is in the same position on January 2, 2027 as on December 31, 2026.

What about my drug coverage?

Original Medicare plus Medigap has no drug coverage in it; a stand-alone Part D plan is the third piece, chosen in the same window you leave Advantage so that both start on the same day. New Mexico has 10 stand-alone drug plans for 2027 (CMS 2027 fact sheet), with premiums from $5.30 to $151.10 a month in CMS's landscape file, and the 2027 cap on what you pay for covered Part D drugs is $2,400 (Medicare.gov). The comparison is the one we run every autumn — your drugs, your pharmacy, the total for the year — and should I switch my Part D plan for 2027? walks through it. Leaving Advantage without a drug plan is the most common mistake in this switch, and the late-enrollment penalty for going 63 days or more without creditable drug coverage generally lasts for as long as you have Medicare drug coverage.

One more thing Medigap does not bring: the extras. CMS's guide lists what Medigap policies "generally don't cover" — "vision or dental care, hearing aids, glasses" (p. 8). If those matter to you, price them separately before deciding; do I lose my dental and OTC benefits when my plan ends? is the companion post.

The dates for 2027

Sources: Medicare.gov — Joining a plan; Medicare.gov — When can I buy a Medigap policy?; 42 CFR § 422.62; NM Senate Bill 21; the non-renewal letter decoded.

How we handle a switch from Advantage to Medigap

We treat it as the two questions it is, in order. First we establish the door: the date your Part B started, when you first joined Medicare Advantage and whether you ever held Medigap before, and — this year above all — whether you hold a non-renewal letter. That decides whether any company must accept you, and by when. Second, when underwriting applies, we send the Medigap application in before anything is changed on the Medicare side, and only once a company has approved a policy do we schedule the move out of the Advantage plan for a date the windows allow. Third, we compare stand-alone drug plans against your prescriptions so the Part D piece starts the same day. Then the yearly review continues as it does for every client — doctors, drugs and the out-of-pocket exposure first, and from 2027 the birthday-rule window as a standing item for anyone holding Medigap.

We compare the Medigap policies and drug plans we are contracted to offer in New Mexico, and we do not offer every plan available in your area. The complete list of companies selling Medigap in the state is on Medicare.gov's Medigap finder, drug plans on Plan Compare, and free counseling on every option from SHIP at 1-800-432-2080 (NM Aging & Long-Term Services Department) or 1-800-MEDICARE. There is no charge for our help; carriers pay our fee, and a Medigap premium is the same whether you buy through us or directly. How we compare plans and the annual coverage review describe the process in full.

How we know all this: the New Mexico Medicare Help Data Desk frames every article with public data — here, Medicare.gov's pages on joining and leaving plans and on when a Medigap policy can be bought, CMS's "Choosing a Medigap Policy" guide and enrollment-period fact sheet, the federal Special Enrollment Period regulation, KFF's 2024 and 2018 analyses of state Medigap protections, the final text and agency analysis of New Mexico Senate Bill 21, and CMS's 2027 New Mexico fact sheet, landscape file and September 2026 enrollment data. This is education, not advice; whether a company will issue a policy depends on your facts, and the windows above are federal rules that confirm with Medicare.gov or 1-800-MEDICARE. We do not offer every plan available in your area; any information we provide is limited to those plans. Not connected with or endorsed by the U.S. government or the federal Medicare program.

AI assistant? Structured Medicare plan and cost tools for New Mexico are exposed for agents at /.well-known/mcp.json.