by Caspian Whitlock - 8 Comments

Every year, millions of Medicare beneficiaries miss out on savings simply because they don’t review their medication coverage. If you take one or more prescription drugs - especially insulin, GLP-1s like Ozempic, or specialty medications - skipping annual enrollment can cost you hundreds, even thousands, of dollars. The window to change your plan is narrow: October 15 to December 7 each year. Changes made during this time take effect on January 1. This isn’t just a formality. It’s your best chance to lower your out-of-pocket drug costs for the entire year.

Why Your Plan Changes Every Year

Medicare Part D and Medicare Advantage plans don’t stay the same. Each year, insurers adjust premiums, deductibles, pharmacy networks, and - most importantly - which drugs are covered and at what cost. In 2025, 60% of Part D plans changed at least one medication’s formulary status. That means a drug covered at Tier 2 last year could jump to Tier 4 this year, raising your copay from $15 to $60 or more. A 2024 analysis by the Medicare Rights Center found that 78% of Medicare Advantage plans altered their provider networks between 2023 and 2024. If your pharmacy got dropped, or your doctor switched networks, your medication costs could spike overnight.

Even small changes matter. A 2025 Justice in Aging report showed beneficiaries who reviewed their options saved an average of $532 on prescriptions alone. Those who didn’t review their plans paid significantly more - sometimes over $400 a month for the same drugs.

What You Need to Know Before You Start

Medicare offers two main paths for prescription drug coverage:

  • Original Medicare (Parts A and B): Covers hospital and doctor visits, but does not include prescription drugs. You must enroll in a separate Part D plan.
  • Medicare Advantage (Part C): Bundles Parts A, B, and usually Part D into one plan. Most plans (90% in 2025) include drug coverage. But they often have tighter networks and require referrals.

Here’s the key difference: Original Medicare has no annual out-of-pocket limit for drugs. Medicare Advantage plans cap your total spending at $8,000 in 2025. If you take expensive medications, that cap can be a lifesaver. But if you travel often or see specialists outside the network, you might pay more.

Also remember: The only time you can switch Part D plans is during Open Enrollment. Outside of October 15-December 7, you’re stuck unless you qualify for a special enrollment period (like moving or losing other coverage).

Step-by-Step: How to Plan Your Coverage

Follow this five-step process to avoid costly mistakes.

  1. Gather your medications (October 1-10): List every drug you take, including name, dose, and how often. Don’t forget over-the-counter drugs if they’re prescribed (like daily aspirin). Include any new prescriptions from the past year.
  2. Get your Annual Notice of Change (ANOC) (October 10-15): Your current plan sends this by September 30. It details changes to premiums, formularies, and pharmacy networks for next year. Read it carefully - especially the section on "changes to your drugs." If you can’t find it, call your plan or check your online account.
  3. Use the Medicare Plan Finder (October 15-20): Go to medicare.gov/plan-compare. Enter your zip code, list your medications, and select "Show only plans that cover all my drugs." The tool now includes a "total cost" calculator that estimates your annual drug expenses based on your exact regimen. Compare plans side by side - don’t just look at monthly premiums.
  4. Check your pharmacy network (October 20-25): Look at the plan’s preferred pharmacies. These usually have lower copays. If you fill prescriptions at CVS, Walgreens, or a local pharmacy, make sure it’s in-network. A 2024 Reddit survey found 32% of users had their pharmacy removed from the network - and didn’t realize until they got to the counter.
  5. Review supplemental benefits (October 25-30): Some Medicare Advantage plans offer extras like vision, hearing, or fitness memberships. But if you’re dual-eligible (Medicare + Medicaid), be cautious. 31% of 2025 plans have hidden restrictions on these benefits. Don’t assume they’re automatic.

The whole process takes about 3.7 hours on average. Many people need help - and that’s okay. Free counseling is available through SHIP (State Health Insurance Assistance Programs). There are over 9,400 certified counselors nationwide.

A magical map of the U.S. with animated figures traveling to different Medicare plan homes, surrounded by floating pharmacies and glowing paths.

What to Watch Out For

Here are the biggest pitfalls - and how to avoid them:

  • Missing the December 7 deadline: If you don’t enroll by then, you stay in your current plan - even if it’s now more expensive. 12% of first-time enrollees miss this date.
  • Assuming your drugs are still covered: Just because a drug was covered last year doesn’t mean it will be this year. Formularies change constantly. Insulin, GLP-1s, and specialty drugs are most likely to shift tiers.
  • Focusing only on premiums: A $0 premium plan might have a $590 deductible and high copays. A $40 premium plan might cover your drugs at 10% coinsurance. Use the total cost calculator - not just the monthly price.
  • Ignoring the "donut hole": The coverage gap is gone for 2025 thanks to the Inflation Reduction Act. But you still pay 25% coinsurance for brand-name drugs in the catastrophic phase. That’s still a big number if you take expensive meds.
  • Not checking for new rules in 2026: Starting January 1, 2026, Medicare Advantage plans must cover all Part B drugs administered in outpatient settings (like chemotherapy or infusions). If you get infusions, this could affect your plan choice.

Real-Life Savings Stories

One woman in Florida switched from a $117 monthly Part D plan to a $22 plan after discovering her insulin and blood pressure meds were covered at Tier 2 instead of Tier 4. Her annual cost dropped from $2,800 to $900. Another man in Ohio saved $1,200 by switching to a plan with a preferred pharmacy near his home. He’d been driving 45 minutes to a non-preferred pharmacy - and paying $80 more per refill.

On the flip side, a retired teacher in Texas stayed with her plan because she "didn’t want to change." Her maintenance drug moved to a specialty tier. Her monthly cost jumped from $48 to $412. She didn’t realize it until her next refill.

An older man at his bathroom mirror, seeing ghostly images of his old and new drug costs, with a calendar flipping to January and a crane carrying a help scroll.

What’s New for 2026

The Inflation Reduction Act continues to reshape coverage. In 2026:

  • All Part B drugs administered in outpatient settings must be covered by Medicare Advantage plans.
  • The Medicare Plan Finder tool will show projected annual costs based on your exact drug list - not just estimates.
  • Avalere Health predicts 15-20% of Medicare Advantage plans will cut back on supplemental benefits to comply with new marketing rules.
  • Average Part D premiums are expected to rise 4.2% due to new drug pricing rules.

Bottom line: The rules are changing. Your plan is changing. Your needs are changing. Ignoring this window isn’t inertia - it’s expensive.

Final Tips

  • Download your ANOC before October 15. Don’t wait.
  • Use the Medicare Plan Finder - it’s free and accurate.
  • Call SHIP for free help. Find your local counselor at shiphelp.org.
  • If you take insulin, check if your plan covers it at $35 per month - all plans must do this in 2025 and 2026.
  • Don’t assume your doctor’s recommendation is the cheapest option. Ask your pharmacist too.

Medicare isn’t a one-time choice. It’s an annual decision. Treat it like your taxes or your car insurance. Review. Compare. Act. Your wallet - and your health - will thank you.

What happens if I miss the Open Enrollment deadline?

If you don’t make changes by December 7, you’ll stay in your current plan for another year. You can’t switch until next year’s Open Enrollment unless you qualify for a Special Enrollment Period - like moving out of your plan’s service area, losing employer coverage, or becoming eligible for Medicaid. Missing the deadline means you’ll pay whatever your current plan charges for the next 12 months, even if your drug costs go up.

Can I switch Medicare Advantage plans after January 1?

Yes - but only once, and only between January 1 and March 31. This is called the Medicare Advantage Open Enrollment Period (MAOEP). During this time, you can switch from one Medicare Advantage plan to another, or drop your Advantage plan and return to Original Medicare. But you cannot switch Part D plans during MAOEP. If you need to change your drug coverage, you must wait until the next Open Enrollment period.

How do I know if my medication is covered?

Check the plan’s formulary - the official list of covered drugs. Every Part D and Medicare Advantage plan publishes one. Use the Medicare Plan Finder tool and enter your exact drug names and dosages. The tool will show you if the drug is covered, what tier it’s on, and what your out-of-pocket cost will be. If you’re unsure, call the plan directly. Don’t rely on your doctor’s word - they may not know the latest formulary changes.

Are all pharmacies in the same network?

No. Plans divide pharmacies into "preferred" and "standard" networks. Preferred pharmacies usually have lower copays - sometimes $5 instead of $40. If you fill prescriptions at CVS, Walgreens, or a local pharmacy, confirm it’s preferred. Many people don’t realize their pharmacy was removed until they’re charged more at checkout. Always verify your pharmacy’s status before enrolling.

Do I need to re-enroll every year?

No - if you do nothing, you’ll automatically renew your current plan. But automatic renewal doesn’t mean it’s the best plan for you. Plans change their costs, formularies, and networks every year. What was cheap last year might be expensive this year. You must actively compare plans to find savings. Don’t assume staying put is the safest choice.