Medicare Supplement
Thinking of Switching Medigap? Read This First
Oklahoma City — If you have a Medicare Supplement (Medigap) policy and you've been thinking about switching to a different one, the rules about when you can switch — and whether an insurer can charge you more or turn you down — can be confusing. The short version: you have a strong federal right to buy Medigap when you first sign up, but after that, your ability to change plans depends on a mix of federal protections, state laws and, in many cases, the insurance company's willingness to accept you.
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Click to call 855-729-3240Key takeaways
- Outside of your one-time Medigap Open Enrollment Period, insurers in most states can use medical underwriting when you apply to switch policies.
- Federal "guaranteed-issue" rights let you buy certain Medigap plans without underwriting in specific situations, such as losing other coverage through no fault of your own.
- Some states add extra protections — like a birthday rule, an anniversary rule, or year-round open enrollment — but Oklahoma residents should confirm current state rules with the Oklahoma SHIP (called SHIP OK) or the Oklahoma Insurance Department.
- Before you drop or switch a Medigap policy, call your SHIP or 1-800-MEDICARE to make sure you'll be accepted into the new plan.
Here's what Oklahoma City readers should know before making a move.
Your one-time Medigap Open Enrollment Period is the strongest window
Under federal rules, your Medigap Open Enrollment Period is a six-month window that starts the month you're 65 or older and enrolled in Part B. During this window, any Medigap insurer that sells policies in your area must sell you one at the best available rate, no matter your health history.
That is the only time federal law gives you an unconditional right to buy any Medigap policy sold in your state. Once it closes, the rules change.
After that window, medical underwriting is usually on the table
Once your Medigap Open Enrollment Period ends, insurers in most states — including Oklahoma — can generally ask health questions when you apply to switch to a new Medigap policy. Based on your answers, they may:
- Approve you at standard rates,
- Charge you a higher premium, or
- Turn down your application altogether.
This is called medical underwriting. It's the main reason a lot of people stay in a Medigap policy they've outgrown: they're afraid they won't qualify for a new one. The healthier you are when you apply, the better your chances — but there are no guarantees outside of the special situations below.
Federal guaranteed-issue rights: your safety net in certain situations
Federal law spells out several "guaranteed-issue" situations where insurers must sell you certain Medigap policies without underwriting, usually within 63 days of a qualifying event. Common examples include:
- Your Medicare Advantage plan leaves Medicare or stops serving your area.
- You move out of your plan's service area.
- Your employer or union coverage that paid after Medicare is ending.
- Your Medigap insurance company goes bankrupt or you lose the coverage through no fault of your own.
- You joined a Medicare Advantage plan when you first became eligible for Medicare and want to switch back to Original Medicare within your first year (the "trial right").
The specific Medigap plans available under a guaranteed-issue right can be limited, so it's worth reading medicare.gov's Medigap guide carefully, or calling 1-800-MEDICARE, before you make a change.
State add-ons: birthday rules, anniversary rules and continuous open enrollment
On top of federal law, some states have added their own protections. Depending on the state, these can include:
- A birthday rule, letting you switch to an equal or lesser Medigap plan around your birthday each year without underwriting.
- An anniversary rule, tied to the date you first bought your current policy.
- Continuous or year-round open enrollment, where insurers can't use health underwriting at all.
These rules vary widely and change over time. Oklahoma isn't among the states most commonly cited for a birthday or anniversary rule, but state rules do get updated, so don't rely on what a neighbor in another state tells you. Confirm what applies in Oklahoma today by calling the free Senior Health Insurance Counseling Program (SHIP) run through the Oklahoma Insurance Department, or by checking with the department directly.
A word about Oklahoma City and county-level coverage
Oklahoma City sits mostly in Oklahoma County, with parts extending into Cleveland, Canadian and Pottawatomie counties. Unlike Medicare Advantage and Part D plans, which are sold based on the county you live in, Medigap policies are regulated at the state level. That means the same Medigap rules generally apply across Oklahoma, no matter which of those counties you call home — but which specific policies are offered, and at what price, depends on the insurance companies licensed in Oklahoma.
Before you switch, do these four things
1. Don't cancel your current policy first. You typically have a 30-day "free look" period after buying a new Medigap policy to decide whether to keep it. Keep paying premiums on the old one until you're sure. 2. Ask if you'll be underwritten. Call the new insurer and ask directly whether health questions apply and whether you qualify for a guaranteed-issue right. 3. Compare apples to apples. Medigap plans are standardized by letter (Plan G, Plan N, etc.), so the benefits within a lettered plan are the same across companies — but premiums and customer service can differ. 4. Get free, unbiased help. Oklahoma's SHIP counselors don't sell insurance and don't earn commissions.
By the numbers
Medicare Part B premium, 2006–2026
The standard monthly Part B premium has climbed from $88.50 in 2006 to $202.90 in 2026. Hover any point for that year’s premium.
Source: CMS. Standard premium shown; in some hold-harmless years many existing enrollees paid less. Confirm at Medicare.gov.
By the numbers
How people get Medicare in Oklahoma County
(MA penetration in Oklahoma County)
MA penetration from CMS enrollment data; Medigap share is an estimate. U.S. average is about 54% Medicare Advantage. These are area-level figures, not plan-specific.
Key dates
Medicare enrollment periods at a glance
- Around your 65thInitial Enrollment PeriodA 7-month window around the month you turn 65 — your first chance to sign up.
- October 15 – December 7Annual Enrollment PeriodAnyone with Medicare can join, switch, or drop a Medicare Advantage or Part D plan.
- January 1 – March 31Medicare Advantage Open EnrollmentIf you're already in a Medicare Advantage plan, you can make one change.
- January 1 – March 31General Enrollment PeriodFor people who missed their first chance to sign up for Part B.
- VariesSpecial Enrollment PeriodTriggered by life events like moving or losing other coverage.
Dates are set by Medicare and apply nationwide. Confirm your personal windows at Medicare.gov or 1-800-MEDICARE.
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The parts of Medicare
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When can you enroll? An interactive year
Enrollment windows are federal and the same nationwide. Confirm your personal dates at Medicare.gov or 1-800-MEDICARE.
Good to know
Frequently asked questions
Can I switch Medigap plans anytime I want?
Does Oklahoma have a Medigap birthday rule?
What if I have a Medicare Advantage plan and want to add Medigap?
Where can I get personal help without a sales pitch?
- CMS — Medicare Supplement Insurance (Medigap) rules (medicare.gov)
For personalized answers, contact Medicare.gov, 1-800-MEDICARE, or your local SHIP.
Also for Oklahoma City
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This page was last updated: September 2026.