If you've ever renewed your car insurance through Costco or bought a home security system in the warehouse aisle, the idea of picking up a Medicare Advantage plan alongside your bulk olive oil may not sound as strange as it first appears. A new retail distribution partnership is moving Medicare plan shopping into one of America's most trusted membership brands, and for the roughly 76 million Costco members across the United States, it could soon mean a very different kind of open enrollment experience. But before you toss a Medicare plan into your flatbed cart, there are real questions every beneficiary should ask — about networks, drug coverage, out-of-pocket costs, and whether the convenience of a familiar brand actually translates into a better health plan for your specific situation.
The core concept behind the Costco Medicare partnership is retail distribution, not plan creation. Costco itself is not becoming a health insurance company. Instead, it is acting as a distribution channel — a trusted storefront, both physical and digital — through which a licensed Medicare Advantage insurer can reach members who already have a relationship with the brand. This is not entirely new territory in American insurance. Costco has long offered auto, home, and life insurance products through partnerships with established carriers. The difference here is that Medicare Advantage is a federally regulated health benefit, and the stakes for getting it wrong are considerably higher than choosing the wrong auto deductible.
Medicare Advantage, also called Medicare Part C, is offered by private insurance companies approved by the Centers for Medicare & Medicaid Services. These plans must cover everything Original Medicare covers — hospital care under Part A and medical services under Part B — and most also include prescription drug coverage (Part D) and extras like dental, vision, and hearing benefits that Original Medicare does not cover. In 2025, according to CMS.gov data, there were approximately 4,800 Medicare Advantage plans available nationwide, with an average monthly premium for Medicare Advantage plans with drug coverage of around $17, though many beneficiaries pay more depending on their region and plan type. The average beneficiary had access to 43 Medicare Advantage plans in their county, meaning the market is already crowded — and adding a Costco-branded entry point does not reduce the complexity of choosing wisely.
Data Snapshot: According to CMS.gov enrollment data, Medicare Advantage enrollment surpassed 33 million beneficiaries in 2024, representing more than 54% of all Medicare-eligible Americans. CMS star rating data for 2025 showed that only about 31% of Medicare Advantage plans earned 4 stars or higher — the threshold CMS uses to designate high-quality plans — meaning the majority of available plans fall below that benchmark. When a new distribution channel like Costco brings additional plans to market or promotes existing ones, the star rating of the specific plan being offered matters enormously and should be the first thing you look up at Medicare.gov's Plan Finder tool.
So what might a Costco Medicare Advantage plan actually look like in practice? Based on how similar retail partnerships have worked in the insurance industry, members would likely access plan information through Costco's website or through in-warehouse kiosks and events, with licensed insurance agents available to walk through options. The plans themselves would be underwritten and administered by the insurance carrier partner, not by Costco. That means your claims, your prior authorizations, your appeals, and your customer service calls all go through the insurer — not the warehouse. Costco's role is essentially to get you in the door and make the initial shopping experience feel less intimidating. Whether the underlying plan is competitive depends entirely on the carrier, the county you live in, and your personal health needs.
One of the most important things to understand about Medicare Advantage is that these plans are intensely local. A plan that earns rave reviews in Phoenix may have a thin hospital network in Cleveland. The doctors and hospitals in a plan's network, the specific drugs covered on its formulary, and the out-of-pocket maximum — which in 2025 could be as high as $9,350 for in-network services under CMS rules — vary dramatically from one plan and one ZIP code to the next. The Costco name on a plan tells you nothing about whether your cardiologist is in-network or whether your brand-name medication is covered at a reasonable tier. Those are the questions that determine whether a plan actually works for you, and they require you to dig into the plan's Evidence of Coverage document and use Medicare.gov's drug and provider lookup tools before you enroll.
For beneficiaries currently on Original Medicare with a Medigap (Medicare Supplement) policy, the arrival of a retail Medicare Advantage option is unlikely to be a reason to switch — and may actually be a reason to stay put. Medigap plans, which are sold by private insurers to cover the gaps in Original Medicare like deductibles and coinsurance, give you access to any doctor or hospital that accepts Medicare anywhere in the country. Medicare Advantage plans, by contrast, typically require you to use a network and may require referrals to see specialists. If you travel frequently, have complex health needs, or see multiple specialists, the freedom of Original Medicare plus a Medigap plan may be worth more to you than the extra benefits and lower premiums that Medicare Advantage often advertises. Average Medigap Plan G premiums in 2025 ranged from roughly $100 to $300 per month depending on your age, gender, location, and the insurer — a meaningful cost, but one that buys you predictability and nationwide access.
If you are currently enrolled in a Medicare Advantage plan and are curious about whether a Costco-distributed plan might be better, the Annual Enrollment Period running from October 15 through December 7 each year is your primary window to make a switch. Any change you make during AEP takes effect January 1 of the following year. There is also the Medicare Advantage Open Enrollment Period from January 1 through March 31, during which you can switch from one Medicare Advantage plan to another, or drop Medicare Advantage and return to Original Medicare, one time. Outside of these windows, you generally cannot change plans unless you qualify for a Special Enrollment Period triggered by events like moving to a new service area, losing other coverage, or qualifying for Extra Help with drug costs.
For beneficiaries who are new to Medicare — typically those turning 65 or newly qualifying due to disability — the Initial Enrollment Period runs for seven months: three months before your birthday month, your birthday month itself, and three months after. This is your most important window, because if you delay enrolling in Part B without qualifying coverage from an employer, you may face a permanent late enrollment penalty of 10% added to your Part B premium for every 12-month period you were eligible but not enrolled. In 2025, the standard Part B premium was $185 per month, meaning even a one-year delay could cost you an extra $18.50 per month for the rest of your life on Medicare.
The Costco partnership also raises a practical question about how beneficiaries will receive guidance during the enrollment process. Federal rules require that anyone selling Medicare Advantage plans be a licensed insurance agent or broker, and that sales presentations follow strict CMS marketing guidelines. Agents cannot pressure you to enroll on the spot, cannot offer gifts worth more than $15 to influence your decision, and must give you time to review plan materials. If you attend a Costco Medicare enrollment event — whether in-store or online — you have the right to ask the agent for their license number, ask whether they represent multiple carriers or only one, and take the plan documents home to review before making any decision. An agent who represents only one carrier cannot tell you whether that carrier's plan is the best option in your area — only an independent broker with access to multiple plans can do that.
For beneficiaries who want to compare plans without any sales pressure at all, the State Health Insurance Assistance Program, known as SHIP, offers free, unbiased counseling in every state. SHIP counselors are not paid commissions and have no financial interest in which plan you choose. You can find your local SHIP program at shiphelp.org or by calling 1-800-MEDICARE. This is especially valuable if you are considering switching from Original Medicare to Medicare Advantage for the first time, because that decision has long-term implications — particularly if you later want to switch back and find that Medigap insurers in your state can use medical underwriting to deny you coverage or charge higher premiums based on your health history. (Notable exceptions include states with guaranteed issue protections for Medigap year-round, such as New York and Connecticut, and states with birthday rules that give you a 30-day window each year to switch Medigap plans without underwriting, including California, Oregon, Nevada, Illinois, and several others.)
The bottom line on the Costco Medicare development is this: retail distribution of Medicare Advantage plans is a marketing innovation, not a coverage innovation. The plan you buy through Costco is subject to the same federal rules, the same CMS oversight, and the same network and formulary limitations as any other Medicare Advantage plan. The potential upside is that a trusted brand may make the initial shopping experience feel more approachable for beneficiaries who find the Medicare landscape overwhelming — and that is genuinely valuable. The risk is that brand familiarity substitutes for careful plan comparison, and that beneficiaries enroll in a plan because they trust Costco without verifying that the specific plan works for their doctors, their drugs, and their budget. Do the homework first. Use Medicare.gov's Plan Finder. Call SHIP. And remember that the best Medicare plan is not the one with the most recognizable logo on the card — it is the one that covers your specific needs at a cost you can sustain.