Medicare decisions can affect your premiums, coverage, doctors, prescriptions, and out-of-pocket costs. The good news is that many problems are easier to avoid when you know which dates and documents matter.

These are general educational tips. Medicare rules and plan benefits can change, so confirm details with Medicare, your plan, employer benefits office, or a licensed professional.

1. Missing your Initial Enrollment Period

The Medicare Initial Enrollment Period usually lasts 7 months: 3 months before you turn 65, your birthday month, and 3 months after. Missing it can mean delayed coverage and a Part B late-enrollment penalty. The fall Annual Enrollment Period is not a general replacement for signing up for Original Medicare Part A or Part B.

Avoid it: Find your IEP dates at Medicare.gov and apply through Social Security when required.

2. Assuming employer coverage always lets you delay Part B

The Special Enrollment Period protection generally depends on coverage through your or your spouse’s current employment. Retiree coverage and COBRA are not the same as current-employment coverage for this purpose.

Avoid it: Ask the employer benefits office how the plan coordinates with Medicare and keep proof of coverage.

3. Treating COBRA as a safe substitute for Medicare enrollment

COBRA can continue employer coverage for a limited period, but choosing COBRA does not generally extend the 8-month Special Enrollment Period for Part B that follows the end of current employment or job-based coverage. Medicare advises people to understand the timing before employment ends.

Avoid it: Read Medicare’s working-past-65 guidance and speak with the employer plan administrator before choosing COBRA.

4. Delaying Part D without checking creditable drug coverage

After the applicable Initial Enrollment Period ends, going 63 or more consecutive days without Medicare Part D or other creditable prescription drug coverage may result in a Part D late-enrollment penalty later.

Avoid it: Request the plan’s written creditable-coverage notice and review Medicare’s Part D penalty rules.

5. Assuming Medigap has an annual open enrollment period

Medigap is different from Medicare Advantage and Part D. The key federal Medigap Open Enrollment Period generally begins when you are 65 or older and enrolled in Part B, lasts 6 months, and gives important guaranteed-issue protections. Outside protected situations, medical underwriting may apply under federal law and state rules.

Avoid it: Compare Medigap timing before enrolling in Part B. See Medicare’s Medigap guidance and check Texas requirements with the Texas Department of Insurance.

6. Confusing Original Medicare with Medicare Advantage

Original Medicare is Part A and Part B administered by the federal program. Medicare Advantage, also called Part C, is offered by private Medicare-approved plans and must cover medically necessary services covered by Parts A and B, subject to plan rules. Costs, networks, referrals, and prior authorization can differ.

Avoid it: Compare provider access, prescriptions, premiums, cost-sharing, and coverage rules using Medicare’s plan comparison tool.

7. Choosing a plan for extras alone

Dental, vision, hearing, transportation, meals, and over-the-counter allowances may be offered by some Medicare Advantage plans, but benefits, limits, networks, and eligibility rules vary and may change each year.

Avoid it: Read the plan’s Evidence of Coverage and Annual Notice of Change. Treat extra benefits as one factor, not the entire reason to choose a plan.

8. Skipping the formulary check

A formulary is a plan’s covered-drug list. Plans can have tiers, restrictions, quantity limits, step therapy, and prior authorization. A drug’s coverage and cost can change under the plan’s rules.

Avoid it: Check every prescription, dose, pharmacy, tier, and restriction in the current Medicare Plan Finder before enrolling.

9. Picking a drug plan without comparing total costs

The lowest monthly premium is not necessarily the lowest annual cost. Deductibles, copayments, coinsurance, pharmacy networks, drug tiers, and coverage rules all matter.

Avoid it: Compare estimated yearly drug costs and verify the result with your prescribers and pharmacy.

10. Assuming every doctor and facility accepts your plan

Original Medicare and Medicare Advantage use different provider rules. Medicare Advantage plans may have service areas and provider networks, and a facility’s participation does not guarantee that every clinician involved participates in the same way.

Avoid it: Confirm the doctor, hospital, facility, specialists, and referral or authorization requirements directly with the plan before planned care.

11. Ignoring the Annual Notice of Change

Medicare Advantage and Part D plans send an Annual Notice of Change each fall describing changes that take effect in January, such as premiums, cost-sharing, networks, formularies, and benefits.

Avoid it: Compare the notice with your prescriptions, doctors, and expected care. The Medicare Annual Enrollment Period generally runs October 15 through December 7 each year.

12. Looking only at the monthly premium

Premiums are only one part of cost. Depending on the coverage, you may also pay deductibles, copayments, coinsurance, drug costs, and other out-of-pocket amounts. Medicare Advantage plans have a yearly limit on covered Part A and Part B services, while Original Medicare does not have a yearly out-of-pocket limit unless you have supplemental coverage.

Avoid it: Compare realistic annual and worst-case costs, not just the premium.

13. Relying on advertisements or trying to do everything alone

An advertisement is not a complete plan comparison, and an agent or broker may represent only certain plans. Medicare offers official information and phone support at Medicare.gov and 1-800-MEDICARE.

Avoid it: Use more than one source, ask what plans an agent represents, verify licenses and plan availability, and do not share Medicare or financial information with unsolicited callers.

Before you act

Use Medicare.gov, your plan documents, your employer benefits office, SHIP, or a licensed professional to confirm the rules that apply to you. Do not change coverage or prescriptions based on this article alone.

13 Common Medicare Mistakes and How to Avoid Them