Before you compare anything

Find your Annual Notice of Change (ANOC).If you're in a Medicare Advantage and/or Part D plan, your plan should have mailed you an Annual Notice of Change by September 30, explaining its changes for the new year; it spells out next year's premiums, deductibles, and covered drugs.
Pull together your current plan details.Have your Medicare card and plan ID number on hand before you start comparing.
List every medication you take, with exact dosages.You'll need this to check next year's drug coverage, not just this year's.
List your must-keep doctors and facilities.Write down the ones you'd be upset to lose network access to.

Reviewing your current coverage

Check your plan's new premium, deductible, and out-of-pocket maximum.Compare the new monthly premium, deductible, and out-of-pocket maximum against what you pay now; costs reset every January even if you change nothing.
Check every drug on your list against next year's formulary.Plans can add, remove, or move drugs to a pricier tier, so don't assume this year's coverage carries over.
Check whether your doctors and hospitals are still in-network.Networks shift yearly even when the plan name stays the same.
Check the plan's star rating. if choosing between similar plansA plan's rating can improve or decline over time, making it worth checking even if you've been enrolled with the same insurer for several years, though star ratings shouldn't replace comparisons of doctors, medications, and costs.
Check what's happened to extra benefits.Dental, vision, hearing, OTC allowances, and flex cards get adjusted or dropped yearly — don't assume last year's perks stuck around.

Use the Medicare Plan Finder at Medicare.gov/plan-compare.It checks every plan in your ZIP code against your actual drug list and pharmacy, giving you real cost estimates instead of guesses.
Confirm any drug-free Medicare Advantage plan comes paired with separate Part D coverage.A Medicare Advantage HMO or PPO that doesn't cover drugs can't be paired with a separate Medicare drug plan, so joining one leaves you without Medicare drug coverage.
Check if you now qualify for Extra Help or a Medicare Savings Program. if income or assets changedWorth a look if your income or assets changed this year; these can lower your drug costs or even your Part B premium.
Think twice before dropping Medigap for Medicare Advantage. if considering dropping medigapSwitching back later usually means medical underwriting once your one-time guaranteed-issue window has passed, so this isn't easily reversible.
Call your State Health Insurance Assistance Program (SHIP) for a second opinion.This counseling is free and unbiased — use it if the choice feels complicated.

Never give your Medicare number to anyone who calls you first.There are no 'official' Medicare sales representatives and Medicare does not cold call to enroll beneficiaries or offer you a different plan.
Be suspicious of anyone offering a gift for enrolling.Watch out for people who promise you a gift for enrolling in one of their plans — it's a ploy to get your personal information, such as your Medicare ID and Social Security number.
Hang up and call Medicare or your plan directly if anything feels off.Use the number on your card or Medicare.gov, not a callback number a caller gives you.

Submit your enrollment request before December 7.In most cases, this is the last day to change Medicare coverage for the next calendar year; a health or drug plan must get the enrollment form by December 7.
Get written or online confirmation of your new enrollment.Don't rely on a verbal promise from an agent — keep the confirmation number or letter.
Hold onto your old plan's card until January 1.Changes submitted now don't start until then, so you'll still need current coverage in the meantime.
Watch for your new ID card and welcome packet in December.If it hasn't arrived by early January, call the new plan to confirm you're actually enrolled.
Know your current plan renews automatically if you do nothing.Missing December 7 isn't a penalty — it just means no changes until next year's window (or the narrower Medicare Advantage-only switch period in January–March).