Medicare Part D still affects seniors, caregivers and people picking retiree plans. It pays for outpatient prescription drugs, but plan choice and timing change how much you pay. Here's a quick snapshot followed by a step-by-step guide to enroll, check coverage, save money and file appeals.

Quick reference

- Annual Enrollment Period (AEP): Oct. 15–Dec. 7, 2026.

- Initial Enrollment Period (turning 65): 3 months before, month of, 3 months after your 65th birthday.

- Medicare phone: 1-800-MEDICARE (1-800-633-4227). Website: https://www.medicare.gov.

- New in 2026: GLP-1 bridge program launches July 2026 for Part D and Medicare Advantage drug coverage for weight-loss use with prior authorization. Out-of-pocket GLP-1 retail costs can exceed $1,000 per month without coverage.

- Use the Medicare Plan Finder to compare plans: https://www.medicare.gov/plan-compare.

Prerequisites

Before you enroll or switch Part D plans, have these items ready.

1. Medicare number and red, white and blue Medicare card — or your Medicare Advantage paperwork if you already have Part C with drug coverage. If you don’t have a card, apply at https://www.ssa.gov/benefits/medicare/.

2. A current list of medications, including exact drug names, dosages and how often you take them. Note whether any drug requires special handling — injectables, biologics, or drugs that require refrigeration.

3. Pharmacy information.

List your preferred pharmacy chain and a backup pharmacy in your ZIP code. Some plans have preferred pharmacies that cut your costs.

4. A calendar or reminder system for key dates: AEP (Oct. 15–Dec. 7), Initial Enrollment, and any Special Enrollment Periods (for example, losing employer coverage).

Step-by-step: How to enroll, compare and switch Part D plans (2026)

I'll walk you through enrollment, comparing plans and switching during open periods — the numbered steps keep things straightforward.

Step 1 — Confirm whether you need Part D

1. Check whether you already have creditable drug coverage. Employer plans, TRICARE and some VA benefits count. If your current coverage is creditable, you won't owe a late-enrollment penalty if you keep that coverage.

2. If you’re enrolled in Medicare Advantage (Part C) that includes drug coverage, you generally don't need a separate Part D plan.

Step 2 — Gather costs and plan details

1. Go to the Medicare Plan Finder: https://www.medicare.gov/plan-compare. Enter your ZIP code and your drug list. The tool shows premiums, estimated yearly drug costs, deductibles, and pharmacies in your area.

2. Note the plan’s formulary (drug list), tiers, prior authorization rules, step therapy, and mail-order options. These affect out-of-pocket costs more than the headline premium sometimes.

Step 3 — Don't focus on the monthly premium alone; look at your total expected annual cost.

1. Use the Plan Finder’s estimated annual drug cost for your exact drug list. That estimate combines premiums, copayments, coinsurance and expected coverage phases.

2. Don't be fooled by a low premium — if a plan slots your medicines on high tiers or forces frequent prior authorizations, you'll end up paying more.

Step 4 — Enroll or switch

1. During AEP (Oct. 15–Dec. 7): You can join, switch, or drop a Part D plan or change Medicare Advantage plans that include drug coverage. Enrollment takes effect Jan. 1, 2027.

2. To enroll: use https://www.medicare.gov, call 1-800-MEDICARE, or enroll directly with the plan via the insurer’s website or phone line. If you prefer help, contact State Health Insurance Assistance Program (SHIP) at https://www.shiptacenter.org/ or your state’s Medicare help line.

Step 5 — After enrollment

1. Check your plan confirmation. Make sure listed drugs and your preferred pharmacy are correct.

2. If a drug requires prior authorization, start early. Ask your prescriber to file for prior authorization before your plan rejects a claim at the pharmacy.

Special cases — if you have low income or both Medicare and Medicaid, read this section closely.

1. If you qualify for Extra Help (Low-Income Subsidy), you’ll likely have lower premiums and copays. Apply at Social Security: https://www.ssa.gov/benefits/medicare/ or via your state Medicaid office.

2. Dual-eligible beneficiaries (Medicare and Medicaid) usually have automatic access to a low-cost Part D plan — check your state Medicaid agency for details.

How the GLP-1 bridge program affects plan choice in 2026

1. Starting July 2026, Medicare launches a GLP-1 bridge program allowing beneficiaries with Part D or Medicare Advantage drug coverage to access GLP-1 medications for weight-loss use with prior authorization. The program can cut what beneficiaries pay out of pocket — retail prices for GLP-1 drugs can top $1,000 a month without coverage.

2. Beginning 2027, Part D plan sponsors decide whether to cover GLP-1s for weight loss in their formularies. So during the 2027 AEP, compare each plan’s stance on GLP-1 coverage if that’s relevant to your care.

3. For questions about these programs, call CMS at 1-800-MEDICARE or visit https://www.cms.gov.

Tips to lower Part D costs

- Run your drugs through the Medicare Plan Finder each year — your meds or a plan's formulary can change, so last year's bargain might cost you more now.

- Consider mail-order for maintenance meds. Many plans offer 90-day fills at lower rates.

- Talk to your prescriber about therapeutically equivalent generics or lower-cost alternatives. Ask for 90-day prescriptions where safe and allowed.

- If you hit a coverage hurdle (prior authorization or step therapy), your prescriber can file an exception request or appeal. Use the plan’s formulary exception process and keep copies of everything.

- If you have low income, apply for Extra Help. Even small copays can add up — Extra Help may eliminate the Part D premium and lower copays.

Common mistakes to avoid

1. Missing AEP dates. If you don’t enroll or switch during Oct. 15–Dec. 7, you generally must wait until the next AEP unless you have a Special Enrollment Period.

2. Choosing by premium alone. A $0 or low-premium plan can have high copays for the drugs you actually take. Always check the Plan Finder’s estimated annual drug cost.

3. Ignoring prior authorization rules. If your drug requires prior authorization, don’t wait until you run out. Start the authorization early to avoid coverage gaps.

4. Letting creditable employer coverage lapse without documentation. If you lose employer drug coverage, get a letter proving you had creditable coverage to avoid a late-enrollment penalty.

5. Failing to re-check formularies each year. Plans change their covered drug lists annually, often effective Jan. 1. A previously covered drug can move to a non-covered status or a higher tier.

Appeals and grievances — step-by-step

1. When a claim is denied: ask the plan for an explanation and the specific reason. The plan must give you instructions for an exception or appeal.

2. Request a coverage determination or exception if your drug isn't on formulary or requires step therapy. Your prescriber should submit clinical information supporting medical necessity.

3. If the plan denies the request, file a standard or expedited appeal. For expedited cases — when delay could harm your health — ask the plan to fast-track the review.

4. If plan-level appeals fail, request a review from Medicare. Call 1-800-MEDICARE or visit https://www.medicare.gov/appeals to learn the next steps.

Where to get official help

- Medicare: https://www.medicare.gov and 1-800-MEDICARE (1-800-633-4227).

- Centers for Medicare & Medicaid Services (CMS): https://www.cms.gov.

- Social Security for Extra Help and enrollment matters: https://www.ssa.gov or 1-800-772-1213.

- State Health Insurance Assistance Program (SHIP): https://www.shiptacenter.org/ for free one-on-one counseling.

Related Articles

Medicare Part D in 2026 still hinges on plan choice and timing. Mark Oct. 15–Dec. 7 on your calendar. Use the Medicare Plan Finder, check formularies every year, and start prior authorizations early — especially for new programs like the GLP-1 bridge that begin July 2026. Call 1-800-MEDICARE or visit medicare.gov for definitive plan details and to file appeals.