Medicare coverage at Costco depends on your plan type, not on Costco itself

Costco pharmacies fill prescriptions for people with any Medicare Part D plan — there is no special "Costco plan" and you do not need to choose a plan because of Costco. What matters is whether your current or future Part D plan has contracted with Costco as a pharmacy network location. Most major Part D plans do include Costco, but the details of your coverage — copay amounts, which drugs are covered, whether you need prior approval — come from your specific plan, not from Costco.

If you already have a Part D plan, you can check Costco's website or call your plan directly to confirm Costco is in your network. If you are choosing a plan during open enrollment, you can search plans by entering Costco as a preferred pharmacy in the Medicare Plan Finder tool, and the results will show you only plans that include it.

Key Takeaways

  • Costco pharmacies accept most major Part D plans, but you must verify your specific plan includes Costco before you fill a prescription there.
  • Your copay at Costco is set by your Part D plan, not by Costco, and may differ from what you pay at other pharmacies in your network.
  • You do not need a Costco membership to use the pharmacy, but you do need a valid prescription and active Medicare coverage.
  • If your current plan does not include Costco, you can switch to a plan that does during the annual open enrollment period (October 15 to December 7) or if you have a may have access to life event.

How to check if your Part D plan covers Costco

Start by finding your plan name and member ID. This information is on your Medicare card or in any paperwork your plan sent you. Then visit Costco.com/pharmacy and look for a link that says something like "Check Plan Coverage" or "Accepted Insurance Plans." Enter your plan name — the tool will tell you whether Costco is in your network.

If the online tool does not give you a clear answer, call your Part D plan's customer service number (on the back of your insurance card) and ask directly: "Does my plan include Costco pharmacy?" They can tell you in seconds and can also tell you what your copay will be for specific medications you take regularly.

Do not assume your plan covers Costco just because you have seen other people use it there. Plans change their networks year to year, and some regional plans may not include Costco at all.

What your copay at Costco will be

Your Part D plan sets your copay amount — Costco does not. If your plan says you pay $10 for a generic drug at any in-network pharmacy, you pay $10 at Costco. If your plan says $25 for a brand-name drug, you pay $25 at Costco. The copay is the same whether you fill the prescription at Costco, CVS, Walgreens, or any other pharmacy in your plan's network.

Some Part D plans offer lower copays at certain pharmacy chains as an incentive to use them. If your plan has a preferred pharmacy program, Costco may or may not be on the preferred list. Check your plan documents or call your plan to find out whether Costco gets a lower copay rate.

You will also pay the same copay whether you fill a 30-day supply or a 90-day supply, unless your plan specifically charges more for longer supplies. Many plans encourage 90-day fills by charging the same copay for three months as for one month — ask your plan whether this applies to you.

Do you need a Costco membership to use the pharmacy?

No. Costco pharmacies are open to anyone with a valid prescription and active Medicare coverage, regardless of membership status. You can walk in, fill your prescription, and leave without ever entering the warehouse or paying a membership fee.

However, if you are already a Costco member, you may find it convenient to pick up groceries or other items while you are there. Costco membership costs $60 per year for a Gold Star membership or $120 per year for an Executive membership, but neither is required to use the pharmacy.

Switching to a plan that includes Costco

If your current Part D plan does not include Costco, you have two main windows to switch. The first is the annual open enrollment period, which runs from October 15 to December 7 each year. During this time, you can switch to any other Part D plan available in your area, including one that covers Costco.

The second is if you have a may have access to life event — a move to a new state, loss of employer coverage, or certain other changes. These events can trigger a special enrollment period outside the annual window. Contact Medicare at 1-800-MEDICARE to ask whether your situation qualifies.

When you are ready to switch, use the Medicare Plan Finder tool at Medicare.gov. Enter your zip code, the medications you take, and select Costco as your preferred pharmacy. The tool will show you only plans that include Costco and will estimate your out-of-pocket costs for your actual prescriptions so you can compare plans side by side.

What happens if you fill a prescription at Costco without verifying coverage first

If you show up at Costco with a prescription and your plan is not in their system, the pharmacy will tell you at the counter. At that point, you have a few options: you can pay out of pocket (Costco often has competitive cash prices), you can ask the pharmacy to hold the prescription while you call your plan to confirm coverage, or you can take the prescription to a pharmacy that is definitely in your network.

If you do pay out of pocket by mistake, contact your Part D plan to ask whether they will reimburse you. Some plans will if you can show you made a good-faith effort to use an in-network pharmacy. This is rare, but it is worth asking.

To avoid this situation entirely, verify coverage before you fill any prescription at Costco, especially if you are using Costco for the first time or if you recently switched plans.

Frequently Asked Questions

Can I use my Medicare Advantage plan at Costco pharmacy?

Medicare Advantage plans (Part C) include prescription drug coverage as part of the plan. Whether Costco is in your network depends on your specific plan. Check your plan documents or call the plan's customer service number to confirm. The process is the same as with standalone Part D plans.

What if I take a medication that is not on Costco's formulary?

Your Part D plan, not Costco, maintains the formulary — the list of covered drugs. If a medication is not covered, it is because your plan does not cover it, not because Costco will not stock it. Call your plan to ask about coverage options, which may include requesting prior authorization or switching to a covered alternative.

Do I pay the same copay at Costco as at other pharmacies?

Yes, as long as both pharmacies are in your plan's network. Your copay is determined by your plan and applies to any in-network pharmacy. However, if your plan has a preferred pharmacy program, Costco may have a different copay than non-preferred pharmacies.

Can I transfer a prescription from another pharmacy to Costco?

Yes. Call Costco pharmacy with your prescription number from your current pharmacy, and they can request the transfer electronically. This usually takes a few hours. You do not need to contact your original pharmacy — Costco handles the request directly.

What if I move to a state where Costco is not available?

If you move, you can switch Part D plans during the special enrollment period that follows a move. Use the Medicare Plan Finder tool to see which plans are available in your new location and choose one that fits your needs. You have 60 days from the date you move to make the switch.