Newsroom · Sioux Falls

Turning 65 in Sioux Falls: your 2026 Medicare enrollment roadmap

One 7-month window, four parts of Medicare, and a network choice that quietly decides your costs for years.

Medicare ATX Data Desk

Published June 15, 2026 · 9 min read · Sourced from CMS.gov

If you're turning 65 in Sioux Falls, your most important Medicare decisions happen inside a single 7-month window — and the choices you make now are hard to undo later. This roadmap walks you through that timeline, the four parts of Medicare, the real 2026 plan landscape in Minnehaha County, and the one local question that decides more than any premium.

Every figure below comes straight from public federal data — the CMS PY2026 plan landscape, CMS county enrollment, 2026 CMS star ratings, CMS Hospital Compare, and CDC local health data. No invented numbers, no "call for pricing."

Step 1: Know your 7-month window

Your Initial Enrollment Period (IEP) is built around your 65th birthday. When you act inside it changes when your coverage starts:

The takeaway: the first 3 months are the sweet spot. Enroll then and your coverage begins the first day of your birthday month with no gap. Wait until after the window closes and — unless you qualify for a Special Enrollment Period because you kept working with employer coverage — you can face Part B and Part D late penalties that last for life.

Step 2: Understand the four parts

"Medicare" is really four pieces, and turning 65 means deciding how to assemble them:

• Part A (hospital) — premium-free for most people who worked 10+ years. Almost everyone takes it at 65.
• Part B (medical) — carries a monthly premium set by CMS each year; higher earners pay an IRMAA surcharge. Delaying it without other creditable coverage triggers a lifelong penalty.
• Part C (Medicare Advantage) — a private bundle of A + B (usually + drugs) with a network and a yearly out-of-pocket cap.
• Part D (drugs) — prescription coverage, either inside an Advantage plan or stand-alone alongside Original Medicare + a Medigap supplement.

The real fork at 65 is Medicare Advantage vs. Original Medicare + a Medigap supplement + Part D. And there's a clock on it: your turning-65 window is the one time you can buy Medigap with guaranteed issue — no medical underwriting. That one-time right is why this decision deserves real attention now, not later.

Step 3: See the Sioux Falls plan landscape

Sioux Falls is the largest Medicare market in South Dakota — 39,532 beneficiaries in Minnehaha County — but the menu is deliberately compact: 5 carriers and no HMO Advantage plans. Here are the 5 standard Medicare Advantage PPOs open to anyone turning 65 in the county:

Source: CMS Medicare Advantage / Part D Landscape (PY2026) & CMS Medicare Advantage & Part D Star Ratings (2026), Minnehaha County.

Two plans — Aetna Medicare Signature and Sanford's Align ChoicePlus — are $0-premium, and Align carries a lower $350 drug deductible. All five sit at the same 3.5★ CMS rating, so for someone new to Medicare the deciding factors are your doctors, your drugs, and the deductible — not the headline premium. (Beyond these PPOs, the county also has Dual-Eligible and Institutional Special Needs Plans and Medica Cost plans; we break the full 15-plan roster down in our all-plans guide.)

Step 4: Do the 2026 cost math

The most common new-to-Medicare mistake is choosing on premium alone. A $0 premium covers exactly one thing — the monthly fee. Here's the 2026 cost framework that actually matters:

The genuinely good 2026 news: the Part D out-of-pocket maximum is now $2,100, so no matter which plan you choose, your annual drug spending is capped for the first time. That shifts the smart comparison toward the formulary tier of your specific drugs and the plan's out-of-pocket maximum — not the premium in isolation.

Step 5: Settle the Sanford-vs-Avera question

This is the local decision that quietly drives everything. Sioux Falls care runs through two competing systems, and your plan's network is the bridge to them:

Source: CMS Hospital Compare — Overall Star Ratings.

Sanford USD Medical Center holds a 5-star CMS rating and Avera McKennan a 4-star — both strong. The wrinkle: Sanford runs its own Medicare plans (Align), so those plans favor the Sanford network. If your doctors are at Avera, that changes which plans fit. Confirming your specific physicians and hospital are in-network for 2026 is the non-negotiable step before you enroll.

Step 6: Match the plan to your health

Premium and network only get you halfway — coverage of your conditions and medications decides the rest. CDC data shows the real chronic-condition load among Minnehaha County adults:

Source: CDC PLACES: Local Data for Better Health, County 2023 (2023).

If you manage blood pressure, diabetes, or arthritis — common here — the plan's drug formulary and specialist network matter far more than its premium. Bring your exact medication list when you compare.

What to watch as you approach 65 in 2026

1. Mark your 7-month window on a calendar — and aim to enroll in the first 3 months.
2. Decide Advantage vs. Medigap early, while your one-time guaranteed-issue Medigap right is active.
3. Confirm Sanford or Avera — and your specific doctors — are in any plan's 2026 network.
4. Run your real drug list against each plan's formulary; weigh the deductible and the $2,100 cap, not just the premium.
5. If you're still working at 65, check whether a Special Enrollment Period lets you delay Part B penalty-free.

How we know all this: Big Sioux Benefits runs every article through a data desk that cross-references the CMS plan landscape, county enrollment, 2026 star ratings, hospital quality data, and CDC health data — built by Strategic AI Architects. Every figure here is from a public federal dataset. This is education, not advice; confirm your plan, costs, and eligibility with a licensed agent or Medicare.gov. We take no payment from any carrier to feature a plan.