Medicare Open Enrollment: Your Complete Annual Guide

Each year, from October 15 through December 7, CMS opens the Annual Enrollment Period (AEP) during which all people with Medicare can review and change their health and prescription drug coverage. Changes take effect January 1 of the following year.

What You Can Change During Open Enrollment

During the Annual Enrollment Period, you may:

• §Switch from Original Medicare to Medicare Advantage, or from Medicare Advantage back to Original Medicare
• §Switch from one Medicare Advantage plan to a different one
• §Join, drop, or switch a Medicare Part D prescription drug plan if enrolled in Original Medicare
• §Add or drop prescription drug coverage within your Medicare Advantage plan

All of these changes are available regardless of your health status during the AEP window.

What You Cannot Change

The AEP does not cover Medigap. In most states, Medigap guaranteed issue rights exist only during the initial six-month Medigap Open Enrollment Period that begins when you are first 65 and enrolled in Part B. That window does not repeat. Outside of it, insurers in most states can apply medical underwriting.

The Medicare Advantage Open Enrollment Period (MA-OEP)

A separate window — January 1 through March 31 — allows MA enrollees to switch to a different MA plan or return to Original Medicare. The MA-OEP cannot be used by someone in Original Medicare to enroll in MA for the first time.

Special Enrollment Periods

Outside the AEP and MA-OEP, coverage changes require a Special Enrollment Period (SEP), triggered by specific events: moving outside your plan's service area, your plan leaving Medicare, losing other creditable coverage, or qualifying for Extra Help (Low Income Subsidy).

How to Compare Plans Using Medicare Plan Finder

CMS maintains Medicare Plan Finder at Medicare.gov — the official free tool for comparing all plans available in your ZIP code. To use it effectively:

1. 01Gather your medications — name, dosage, and frequency for each prescription
2. 02List your preferred providers — doctors, specialists, and hospitals
3. 03Review your Annual Notice of Change (ANOC) — plans must send this by September 30
4. 04Compare total costs, not just premiums — include deductibles, copayments, coinsurance, and out-of-pocket maximums
5. 05Check the formulary — confirm your specific medications are covered and note their tier

Common Mistakes to Avoid

Doing nothing by default. Plans change costs, formularies, and networks annually. Staying in the same plan without reviewing means accepting those changes without knowing what they are.

Focusing only on the monthly premium. Lower premium does not always mean lower total spending.

Not verifying your drugs are still covered. Drugs can be removed or moved to higher-cost tiers each year.

Missing the December 7 deadline. Allow time for processing and consider enrolling before the final days.

The Part D $2,000 Out-of-Pocket Cap

For 2025 plan years, CMS implemented a $2,000 annual out-of-pocket cap on covered Part D prescription drug costs, as required by the Inflation Reduction Act. This cap applies only to drugs on your plan's formulary — making formulary verification more important than ever.

For official information, visit Medicare.gov or call 1-800-MEDICARE, available 24/7.

Educational purposes only. Not financial, tax, or legal advice.