If you’re asking “what is Medicare AEP?”, here’s the plain-English version: it’s your yearly do-over for Medicare Advantage (MA) and Part D drug plans.

It’s when you answer the only questions that really matter: Will my costs go up? Are my doctors in-network? Are my meds still covered? If something’s off, you change it—so January doesn’t surprise you.

What Is AEP?

The Annual Enrollment Period (AEP) is the fall window when people on Medicare can change Medicare Advantage and Part D plans for the year ahead. Plans reset every January, and AEP is your chance to align next year’s coverage with your doctors, drugs, and budget—not the other way around. It applies whether you’re already on an MA plan, need to revisit your Part D coverage, or simply want to confirm that your current setup still fits.

AEP isn’t everything. It’s not your Initial Enrollment Period, not how you sign up for Part B, and not a guaranteed-issue window for Medigap in most states. One more insider tip: during AEP, the last application you submit by Dec. 7 is the one that takes effect.

AEP Dates and When Changes Take Effect

AEP runs Oct. 15–Dec. 7 every year, and any Medicare changes you make take effect on Jan. 1. Don’t wait until the last night. Enroll earlier if you can, keep your confirmation numbers, and save the plan summary for your records. In September, you’ll usually receive your ANOC (Annual Notice of Change) and EOC (Evidence of Coverage)—highlight anything that hits your wallet or access, like premium or deductible moves, drug tier changes, provider or pharmacy network shifts, and trimmed extras.

What You Can Change During AEP (MA & Part D)

Think of AEP as your reset button. You can move between Medicare Advantage plans, switch from MA to Original Medicare (and add a stand-alone Part D plan), or shop for a new Part D plan if your medication mix or preferred pharmacy has changed.

For Medicare Advantage, you can change plan types (HMO to PPO, etc.), choose a different network that fits your doctors and hospital, and pick a benefit mix that matches what you actually use (dental/vision/hearing allowances, OTC cards, transportation, meals). If your 2026 network shrank or your copays crept up, AEP is when you correct course.

For Part D, you’re looking for the best blend of formulary coverage, drug tiers, utilization rules (prior authorization, step therapy, quantity limits), and preferred pharmacies. Build a clean med list and compare plans by total yearly cost, not just the premium. Formularies and pharmacy status change yearly, so last year’s “cheap” plan may not be cheap next year.

What You Can’t Change During AEP (and Alternatives)

AEP doesn’t make Medigap (Medicare Supplement) guaranteed-issue in most states. If you apply for Medigap now, you’ll usually face medical underwriting unless your state has a special rule. AEP also doesn’t enroll you in Part B—if you missed Part B, you typically use General Enrollment (Jan. 1–Mar. 31). And AEP won’t fix employer or COBRA coordination—that requires guidance from your benefits team.

There are workarounds. Some states have birthday/anniversary rules that allow certain Medigap changes without underwriting. You may have a trial right if it’s your first-ever MA plan and you’re within the allowed window to switch to Medigap. Certain events—like plan non-renewal or losing other coverage—can open guaranteed-issue windows. If any of that sounds like you, ask targeted questions before you apply.

AEP vs. MA OEP vs. Special Enrollment Periods

Think of these as three different doors for three different situations. AEP is the fall, once-a-year do-over that anyone on Medicare can use to reset next year’s coverage. MA OEP is a January–March mulligan that only applies if you’re already in a Medicare Advantage plan on Jan. 1.

Special Enrollment Periods (SEPs) are the “life happens” exceptions—move, plan non-renewal, Medicaid/LIS changes, losing creditable coverage, and a few others—that can open a door anytime. Pick the right door for your situation and timing, or you risk missing the window that actually fits your needs.

AEP: Your Fall Do-Over

AEP is for anyone on Medicare who wants to reassess next year’s plan. You can switch a new Medicare Advantage plan, move from MA to Original Medicare + Part D, or swap PDP to PDP. It happens Oct. 15–Dec. 7 and your choice starts Jan. 1.

Remember: the last application you submit by Dec. 7 is the one that sticks. You can’t change your coverage after this date until next year’s annual enrollment period.

MA OEP: The January Mulligan (If You’re in MA on Jan. 1)

If you’re enrolled in a Medicare Advantage plan on Jan. 1, you get one change between Jan. 1st. and Mar. 31st. You might switch MA to MA or drop MA for Original Medicare + Part D.

Changes like these typically begin the first of the next month. If you’re on Original Medicare, MA OEP doesn’t let you jump into MA, and it isn’t a window for PDP-only swaps from Original Medicare.

Special Enrollment Periods (SEPs): Life Happens, Plans Change

SEPs apply when you have a qualifying event, such as moving out of your plan’s area, plan non-renewal, changes in Medicaid or LIS/Extra Help, losing creditable coverage, certain institutional stays, or an occasional 5-star plan SEP (when available).

What you can change depends on the event. SEPs occur year-round, as triggered, with effective dates that vary. Expect documentation, and know that windows can be short.

How to Prepare: Doctors, Drugs, Costs, ANOC

• Doctors & Hospitals: List your PCP, specialists, clinics, and hospital and confirm they’re in-network for 2026 on any plan you’re considering.

• Drugs: Build a current med list. Check each plan’s 2026 formulary for tier changes, prior authorization, step therapy, and quantity limits.

• Pharmacies: Verify your preferred pharmacy is preferred (not just “in network”). Compare mail-order vs. retail by per-fill cost.

• Total-Cost Math: Don’t shop by premium alone—add premium + deductible + typical copays/coinsurance. For MA, factor in the MOOP (maximum out-of-pocket).

• ANOC triage: In September, highlight premium jumps, drug tier moves, network changes, and trimmed extras. Shortlist alternatives before AEP opens.

Brickhouse Approach (MA & Medigap Guidance; PDP via Medicare.gov)

Brickhouse is carrier-neutral and education-first. The goal is to align doctors, drugs, and budget with the right structure—without steering you to a particular company. We’ll pressure-test the plan against your real life: which providers you see, which hospital you’d actually use, and how the MOOP and copays could play out if you had a tough year.

For Part D, we point shoppers to Medicare’s Plan Finder because it runs the most accurate drug-by-drug math. Enter your meds and pharmacies, sort by total yearly cost, and share results if you want a second look. You stay in control while we help you avoid landmines.

The Takeaway: Make AEP Work for You

Your needs drive the decision—doctors, drugs, and dollars. Read your ANOC, confirm networks and formularies, run the totals, and enroll before Dec. 7 so Jan. 1 doesn’t surprise you.

If you’re ready to review your coverage, schedule a free, no obligation consultation today.