For coverage beginning in 2027, Medicare’s Open Enrollment window is October 15 through December 7, 2026. During that period, you can usually join a different Medicare prescription drug plan, drop a stand-alone Part D plan, or change the way you receive drug coverage, depending on your current Medicare arrangement. A request received by December 7 generally takes effect January 1, 2027.
To switch, enroll in the new plan; you normally do not separately cancel the old one. Before submitting the application, compare every prescription on the new plan’s formulary, its restrictions, total expected costs, pharmacy network and eligibility rules. The correct choice depends on your location, medications, pharmacy preferences and current coverage type.
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What you can change during the 2026 Open Enrollment period
Medicare’s annual Open Enrollment period runs from October 15 through December 7, 2026. It is the yearly opportunity to make coverage changes for the following plan year. If the plan receives your enrollment request by December 7, the new coverage generally starts January 1, 2027.
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- Original Medicare with a stand-alone Part D plan: You can generally join another stand-alone drug plan, switch plans, or drop your Part D plan.
- Medicare Advantage: Your drug coverage is usually integrated into the Medicare Advantage plan. You must follow the enrollment options that apply to your Medicare Advantage plan type and location; changing a drug plan alone may not be available.
- No current drug coverage: You may be able to enroll, but delaying Part D can create a late enrollment penalty if you go without Medicare or other creditable prescription coverage for 63 or more consecutive days.
Medicare publishes different options and effective dates for different enrollment periods. Do not assume that a change allowed for someone in Original Medicare is also available to someone enrolled in Medicare Advantage.
How to switch to a different Part D plan
- Confirm that you are allowed to change now. For the 2027 plan year, the annual window is October 15–December 7, 2026. A Special Enrollment Period or a Medicaid or Extra Help rule could permit a change at another time.
- Collect your decision information. Make a list of every prescription, including dose and frequency; the pharmacies you use; your ZIP code; your current plan name; and whether you have employer, union, Medicaid or Extra Help coverage.
- Compare plans available in your area. Use Medicare’s official Plan Finder or call 1-800-MEDICARE. Availability, premiums, formularies and pharmacy networks vary by service area.
- Check the new plan’s formulary. Confirm that each drug is covered and identify its tier, quantity limits, prior-authorization requirement, step-therapy rule and any other utilization restriction.
- Calculate your expected yearly cost. Include premiums, deductible, copayments or coinsurance, preferred versus standard pharmacy pricing, mail-order costs and the cost of drugs that are not covered.
- Submit the enrollment request to the new plan. You can enroll through the plan, Medicare’s online enrollment process or 1-800-MEDICARE. Keep the confirmation number, date and method of submission.
- Wait for written confirmation. The new plan should send a letter stating when coverage begins. Review it for the effective date and the plan selected.
- Give the new information to your prescribers and pharmacy. Ask the pharmacy to update your insurance record before January 1, 2027, and refill medicines early enough to avoid a transition problem.
When you enroll in the new plan, Medicare generally ends your old drug coverage when the new coverage begins. A separate cancellation request is normally unnecessary and can create confusion if it is sent before the replacement enrollment is processed.
What happens to your old plan
Your old drug coverage ends when the new drug coverage begins. For a timely Open Enrollment request, that is generally January 1, 2027. You may receive a confirmation or disenrollment notice from the old plan and an enrollment letter from the new plan.
Do not assume that an application is complete merely because you submitted information online. Save the submission receipt, confirmation code or call reference. If the new plan does not send confirmation, contact it or 1-800-MEDICARE before the effective date and ask whether the enrollment was accepted and what date Medicare has on record.
If both plans appear active
Overlapping plan records can occur while enrollment files are being processed. Use the effective date shown in Medicare’s confirmation as the controlling date. Ask the plans which coverage should be billed for a prescription filled near the transition and retain receipts while the records are corrected.
If the new plan rejects a prescription
At the pharmacy, verify that the pharmacist has the new member number and that the fill date is on or after the new plan’s effective date. If the drug is excluded, subject to prior authorization or placed on a different tier, ask the prescriber and plan about the plan’s exception or authorization process. Do not stop a medication without medical advice.
How to compare Part D plans before enrolling
The cheapest monthly premium is not necessarily the lowest total cost. Compare the following items using your actual medication list and expected pharmacy use.
| Comparison point | What to check | Why it matters |
|---|---|---|
| Drug coverage | Every prescription, strength, dosage form and quantity on the formulary | A plan that excludes one regular drug may cost more after paying cash or pursuing an exception. |
| Coverage rules | Prior authorization, step therapy, quantity limits and refill rules | Restrictions can delay a prescription or require trying another treatment first. |
| Premium and deductible | Monthly premium, annual deductible and when cost sharing starts | A lower premium can be offset by a higher deductible or higher drug copayments. |
| Drug tiers | Copayment or coinsurance for each of your drugs | Tier placement differs by plan and can change your cost substantially. |
| Pharmacy network | Whether your preferred pharmacy is in-network and whether it is preferred | The same prescription may cost more at a standard or out-of-network pharmacy. |
| Mail order and delivery | Availability, quantities, shipping rules and pricing | Mail order may be useful for maintenance medicines but may not suit urgent prescriptions. |
| Eligibility | Plan service area, Medicare coverage type and enrollment restrictions | A plan shown in another ZIP code may not be available where you live or may not fit your coverage. |
Check the formulary drug by drug
Search the exact drug name, dose and form. A plan may cover a tablet but not an extended-release version, or cover one quantity while limiting another. Record the tier and any notation indicating prior authorization, step therapy or quantity limits. If a drug is missing, ask the plan whether a medically appropriate alternative is covered and how your prescriber can request an exception.
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List the number of fills you expect in each month and calculate premium plus deductible plus cost sharing. Include seasonal or occasional medicines, because a plan that looks inexpensive for one prescription may be costly when several drugs are filled throughout the year. Compare the total for each plan under the same medication assumptions.
Check pharmacy pricing
Enter the pharmacies you actually use. Plans can designate pharmacies as preferred or standard, producing different copayments for the same drug. Confirm whether a local independent pharmacy, chain, mail-order service or long-term-care pharmacy participates before enrolling.
Questions to answer before choosing
Write down the answers rather than relying on memory while comparing plans:
- Will every prescription I take in 2027 be covered in the exact strength, form and quantity I need?
- Does any drug require prior authorization, step therapy or a quantity limit, and who must submit the paperwork?
- Which pharmacy gives the lowest quoted price for each medicine, and is that pharmacy convenient for urgent fills?
- What is my estimated total annual cost, including premiums, deductible, copayments, coinsurance and mail-order charges?
- Is the plan available at my address and compatible with Original Medicare or my Medicare Advantage enrollment?
- Will changing plans affect employer, union, Medicaid or Extra Help coverage?
Ask the plan to explain an answer that is unclear and note the representative’s name, the date and any reference number. Formulary information and pharmacy pricing are plan-specific, so a result for a different ZIP code or an earlier plan year is not a reliable substitute.
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Dropping Part D coverage: the consequences
Dropping a stand-alone Part D plan is different from switching to another plan. If you leave without Medicare drug coverage or other creditable prescription coverage for 63 or more consecutive days, Medicare may require you to wait for an enrollment period and may charge a late enrollment penalty. The penalty can affect future Part D premiums.
Before you disenroll, identify the replacement coverage and its start date. Employer or union prescription coverage may be creditable, but you should obtain confirmation from the benefits administrator rather than assume it is. Keep written proof of any other coverage and its dates.
What “creditable” coverage means for your decision
For this purpose, the key issue is whether the other prescription coverage is recognized as creditable by Medicare. Ask the employer, union or administrator specifically whether the coverage is creditable and request the answer in writing. Record the date the coverage starts and ends. If there is any gap approaching 63 consecutive days, call Medicare promptly rather than waiting for the next annual window.
Medicare Advantage and Part D changes
Many Medicare Advantage plans include prescription drug coverage. If you are enrolled in one of those plans, the annual Open Enrollment choices are governed by Medicare Advantage rules, not simply stand-alone Part D rules. A move to a different Medicare Advantage plan may change your medical and drug benefits together. Moving from Medicare Advantage to Original Medicare may require selecting a stand-alone Part D plan to avoid going without drug coverage.
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Special Enrollment Periods and other exceptions
You may not have to wait until October if a qualifying event gives you a Special Enrollment Period. Examples include moving outside your plan’s service area or losing other prescription coverage. The permitted action and deadline depend on the event, and Medicare may require documentation.
People with Medicaid or Extra Help can have a monthly opportunity to make certain plan changes, subject to exceptions. The exact options vary with the person’s eligibility and current coverage. Check the current Medicare rules for the specific event instead of relying on a general calendar.
Employer or union coverage
The 2026 Medicare & You handbook cautions people with employer or union coverage to contact their benefits administrator before making a Medicare change. Enrolling in another plan or dropping existing coverage can affect the employer or union plan, your eligibility for it and the coverage of dependents. Obtain an explanation of the consequences in writing.
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Deadlines and a practical timeline
- Before October 15, 2026: Gather your medication list, current plan documents, pharmacy information and notices about changes for the next year.
- October 15–December 7, 2026: Compare 2027 plans and submit a change if one better fits your needs. Do not wait for the final day if you need help resolving a formulary or eligibility question.
- After submitting: Save proof of enrollment and watch for the new plan’s confirmation letter.
- Late December: Confirm the new member ID, effective date, pharmacy billing information and any required prior authorizations.
- January 1, 2027: The new plan generally begins if the request was received by December 7. Use the new plan card for prescriptions filled on or after that date.
Keep a transition folder
Save your current plan’s annual notice, the new plan’s summary and formulary, enrollment receipts, call reference numbers, confirmation letters and pharmacy receipts in one place. Include a current medication list and prescriber contact information. This record makes it easier to correct a wrong effective date, demonstrate that an enrollment request was timely or ask a plan to review a rejected claim.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Common mistakes to avoid
- Choosing based only on the monthly premium.
- Checking a drug’s name but not its exact dose, tier or restrictions.
- Assuming a preferred pharmacy is in-network without verifying it for the new plan year.
- Canceling the old plan separately before the replacement enrollment is confirmed.
- Ignoring a 63-day gap in creditable coverage.
- Changing coverage without asking an employer or union benefits administrator first.
- Using plan information from the wrong ZIP code or an earlier plan year.
- Failing to save enrollment confirmation and effective-date documents.
- Waiting until December 7 to discover that a prescriber must complete prior-authorization paperwork.
- Comparing plans with an incomplete medication list or leaving out occasional prescriptions.
Where to get enrollment help
Use Medicare’s official Plan Finder for a personalized comparison based on your ZIP code and prescriptions. You can also call 1-800-MEDICARE to ask about enrollment channels, effective dates and whether your current coverage permits the change you want. Have your Medicare number, medication list, pharmacy preferences and current plan information ready.
If a plan’s formulary or authorization rule creates a clinical problem, ask your prescriber about covered alternatives and the plan’s exception process. For employer or union coverage, the benefits administrator is the appropriate source for how a Medicare change could affect that coverage.
What to do after January 1 if something is wrong
Check the first prescription claim under the new plan as soon as coverage begins. If the pharmacy cannot verify eligibility, provide the new member information and ask the plan whether its enrollment file is active. If you paid out of pocket because the record was delayed, keep the receipt and ask the plan how to submit it for review.
For a missing drug, unexpected tier or authorization block, contact the plan’s member services and your prescriber. Ask whether the issue is a data error, a formulary restriction or a required exception request. Document each call and continue following medical advice while the issue is resolved. If Medicare’s record shows the wrong plan or effective date, call 1-800-MEDICARE with your confirmation information.
Frequently Asked Questions
When is Medicare Part D Open Enrollment for 2027 coverage?
The annual Open Enrollment window is October 15 through December 7, 2026. A request received by December 7 generally starts January 1, 2027.
How do I switch Medicare Part D plans?
Compare plans, then enroll in the new plan through Medicare’s Plan Finder, the plan itself or 1-800-MEDICARE. Joining the new plan generally ends the old drug coverage when the new coverage begins, so a separate cancellation is normally unnecessary.
Do I have to cancel my old Part D plan?
Usually no. Medicare generally ends the old drug coverage when the replacement plan begins. Canceling separately before the new enrollment is confirmed can create confusion.
Can I change a Part D plan outside Open Enrollment?
Sometimes. A qualifying Special Enrollment Period, a move outside a plan’s service area, loss of other coverage, Medicaid or Extra Help may allow a change. The permitted action and deadline depend on the specific circumstance.
What should I check on a Part D formulary?
Check every drug’s exact name, strength, dosage form and quantity. Note the tier, prior-authorization requirement, step-therapy rule, quantity limit and refill conditions, then ask about covered alternatives or an exception if needed.
What happens if I go without drug coverage for 63 days?
A gap of 63 or more consecutive days without Medicare or other creditable prescription coverage may lead to a late enrollment penalty and could mean waiting for an enrollment period. Confirm replacement coverage before dropping a plan.
Can changing Part D affect my employer or union insurance?
It can. Contact the employer or union benefits administrator before enrolling in another plan or dropping existing coverage. Ask how the change affects your coverage, eligibility and dependents, and request the answer in writing.
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What if my new plan rejects a prescription in January?
Verify that the pharmacy has your new member number and that the fill date is after the effective date. Contact the plan and prescriber about authorization, tier or exception procedures, keep receipts and do not stop medication without medical advice.
The Bottom Line
Bottom line: For 2027 coverage, compare Medicare Part D options from October 15 through December 7, 2026. Use your exact medication list, pharmacy choices, ZIP code and current coverage type; verify formulary restrictions and total annual cost; enroll in the replacement plan by December 7; and keep the confirmation showing a January 1, 2027 effective date. Do not create a coverage gap or change employer, union, Medicaid or Extra Help coverage without checking the applicable rules.
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