Newsroom · Sioux Falls

Medicare Advantage Ghost Networks: What to Do When Your Sioux Falls Directory Is Wrong in 2026

Real federal data shows Medicare Advantage directories are wrong far more often than beneficiaries assume — and 2026 finally brought both a structural fix and a genuine undo button.

Yes, it happens in Sioux Falls too: a Medicare Advantage plan's provider directory can list a doctor as in-network when that doctor stopped taking the plan months ago, moved offices, or was never really seeing that plan's patients in the first place. Researchers call the resulting mess a "ghost network" — a directory full of listings that look solid on a screen and turn out to be empty the moment you call. For 2026, there's finally a documented federal fix, plus a genuinely new way to undo an enrollment that leaned on bad information.

This isn't a rare glitch. A U.S. Senate committee sent staff out with a script and a phone in 2023 and found that more than four out of five listed mental health providers in a sample of Medicare Advantage directories were unreachable, not accepting new patients, or simply not in the network at all. CMS's own internal reviews, run every year from 2016 through 2018, found roughly half of all provider directory locations had at least one real error. None of that is old news dressed up as new — it's the reason CMS finalized a rule in September 2025 forcing Medicare Advantage plans to submit their directory data directly to the government, and the reason a three-month-old Special Enrollment Period now exists specifically for people who enrolled based on a wrong listing.

Every figure in this guide is sourced and dated below. No number here came from memory or a summary — each one traces to a named federal document or a nonpartisan analysis, fetched and confirmed this week.

What a "ghost network" actually is

A ghost network is the term researchers and Congress now use for a health plan's provider directory that lists doctors who, in practice, aren't really available to see that plan's patients. The doctor might have retired, switched practices, stopped accepting new patients, or dropped the plan's contract entirely — and the directory simply never caught up.

The term network, in this context, means the specific list of doctors, clinics, and hospitals a Medicare Advantage plan has contracted with to provide your care at the plan's negotiated rate. Unlike Original Medicare, which lets you see any provider nationwide who accepts Medicare, a Medicare Advantage plan's coverage — outside genuine emergencies — generally depends on staying inside that specific list. The directory, whether it's the plan's own website or the federal Medicare Plan Finder tool at Medicare.gov, is supposed to be the accurate, current record of who's actually on that list. A ghost network is what happens when it isn't.

This matters more than a typo. If you pick a plan because your cardiologist appears in the directory, and that listing turns out to be wrong, you haven't just been mildly inconvenienced — you may have made a coverage decision, possibly a permanent one for the year, based on information that was never true.

How often this really happens

The most detailed public study of Medicare Advantage ghost networks came from the U.S. Senate Committee on Finance's Majority staff, published May 3, 2023. Staff called 120 mental health providers listed as in-network across 12 different Medicare Advantage plans in six states — Ohio, Pennsylvania, Oregon, Massachusetts, Colorado, and Washington — posing as the adult child of a parent newly enrolled in that plan, seeking a first appointment for depression.

The results were stark. Of the 120 listed providers, 33% turned out to be non-working phone numbers, wrong numbers, or calls that were never returned. Staff could only book an appointment with a provider who was actually in-network and accepting new patients 18% of the time. Overall, more than 80% of the listed, in-network mental health providers staff attempted to reach were "ghosts" — unreachable, not accepting new patients, or not actually in the plan's network at all.

Source: U.S. Senate Committee on Finance Majority Staff, "Medicare Advantage Plan Directories Haunted by Ghost Networks," May 3, 2023. Calls were placed in April 2023.

That study focused specifically on mental health providers, and it's worth being precise about that scope — it isn't a claim that 82% of every kind of provider listing is wrong. But it's not an outlier finding, either. CMS ran its own directory accuracy reviews of Medicare Advantage plans for cardiology, oncology, ophthalmology, and primary care between 2016 and 2018, checking a sample of roughly 10,500 provider locations across 52 organizations each round. The third and most recent round, published November 28, 2018, found that 48.74% of provider directory locations had at least one inaccuracy — a wrong address, a wrong phone number, or a provider listed as accepting new patients who, in fact, was not. Individual plans ranged from a low of 4.63% inaccurate to a high of 93.02%.

Why directories go wrong in the first place

This isn't only a story about careless insurers. Until the CY2026 rule described below, Medicare Advantage plans generally built and maintained their own provider directories, pulling data from their own contracting systems and, in many cases, licensing directory data to Medicare Plan Finder from third-party vendors. A doctor's practice changes constantly — a physician retires, joins a new group, pauses new patients for months while catching up on a backlog, or simply never signed the specific contract a plan's directory assumed they had. Multiply that by every provider a large plan contracts with, and keeping a directory perfectly current is a genuinely hard operational problem, not just a matter of insurers not trying.

What made it worse, historically, was the lack of a single authoritative source. Before 2025, Medicare Plan Finder on Medicare.gov didn't show provider network information at all — you had to leave the comparison tool and check each plan's own website separately, each with its own update schedule and its own error rate. CMS added provider directory information to Medicare Plan Finder itself for the first time in 2025, specifically so beneficiaries could compare plans and check networks in one place. That's a real improvement. It also means, by CMS's own account, that "some provider directory information may be incorrect, especially in this first year" — the government's own words, not an outside critic's.

What it costs you if you don't catch it

The financial risk here isn't abstract. Emergency and urgently needed care is protected no matter what — federal rule requires every Medicare Advantage plan to cover it anywhere in the country, and limits how much you can be billed for it out of network, according to guidance from the State Health Insurance Assistance Program (SHIP) network. That protection has nothing to do with whether your directory was accurate.

Routine, non-emergency care is a different story. If a "ghost" listing leads you to believe a specialist is in-network and you keep seeing them anyway once you learn otherwise — or if you never find out until a bill arrives — you lose the lower, in-network cost-sharing your plan advertised. For 2026, CMS caps a Medicare Advantage plan's in-network out-of-pocket maximum at $9,250, and for PPOs that cover both in-network and out-of-network care, at $13,900 combined, according to a KFF analysis published June 5, 2026. Those are two different ceilings, and the gap between them — nearly $4,700 for 2026 — is real money sitting on the other side of a directory error. The same KFF analysis found the actual average in-network limit enrollees experience is $5,421, and the average combined limit for PPO enrollees is $9,825 — both well under the regulatory maximums, but both a long way from $0.

Put plainly: a doctor who isn't really in-network doesn't just cost you an awkward phone call. If you keep going anyway, you're paying out-of-network cost-sharing — potentially all the way up to that higher combined ceiling — for care you enrolled in the plan specifically believing would cost you the lower, in-network amount.

The new 2026 CMS fix, and the SEP that comes with it

CMS finalized a rule on September 19, 2025 — designated CMS-4208-F2 — that changes who's responsible for directory accuracy on Medicare Plan Finder. Effective November 17, 2025 and applicable starting January 1, 2026, the rule requires Medicare Advantage organizations to submit their provider directory data directly to CMS for publication, rather than relying on third-party vendor data. Plans must update that data within 30 days of learning about a change, and must attest at least annually that the information is accurate.

That's a structural fix aimed at the plans' side of the problem. On the beneficiary side, CMS built something new and specific: a temporary Special Enrollment Period (SEP) — a life-event window that lets you change plans outside the normal enrollment periods — for anyone who enrolled in a Medicare Advantage plan through Medicare Plan Finder based on incorrect provider information.

Source: CMS, "NEW Special Election Period for Incorrect Provider Information in Medicare Plan Finder," CMS Product No. 12231-P, March 2026.

To use it, you have to meet every one of these conditions, per CMS's own notice:

• You enrolled in your Medicare Advantage plan through Medicare Plan Finder on Medicare.gov — not through a plan's own website or a paper application.
• Your plan's effective date falls between January 1 and December 1, 2026.
• You're still within the first three months of that enrollment.
• You discovered that a doctor you were relying on was not actually in your plan's provider network, despite what Plan Finder showed.

If all four are true, you call 1-800-MEDICARE (TTY: 1-877-486-2048) and tell the representative you relied on incorrect Plan Finder provider information. You can use the SEP to enroll in a different Medicare Advantage plan, drop Advantage entirely and return to Original Medicare (adding a stand-alone Part D drug plan if you want one), or enroll in Part D alongside a return to Original Medicare. The new plan takes effect the first day of the month after you apply — plans themselves can't process this SEP directly; it has to go through 1-800-MEDICARE.

How to verify your doctor is really in-network

The single most reliable fix costs nothing and takes a phone call, and it works regardless of which enrollment period you're in or which tool you used. Here's the order that actually catches problems:

1. Check the directory first. Medicare Plan Finder on Medicare.gov now shows provider network information as part of plan comparison, or check the plan's own published directory. This narrows your list; it doesn't confirm it.
2. Call the doctor's office directly — not the plan's customer service line. Call the front desk, the number you'd actually use to book an appointment.
3. Ask the specific question: "Are you in-network for [exact plan name] for 2026, and are you currently accepting new patients under that plan?" A general "we take Medicare" answer isn't the same thing — Original Medicare and a specific Medicare Advantage plan are two entirely different questions to a billing office.
4. Write down who you talked to and when. If a listing turns out to be wrong later, having a name, date, and what you were told is exactly the kind of documentation that makes a grievance or an SEP request faster to resolve.

This is tedious for a full list of doctors, and that's precisely why so many people skip it and lean on the directory instead. It's also precisely the gap that made ghost networks possible in the first place. If your household is doing this for two or three physicians, budget 15-20 minutes per office, mostly spent on hold.

What to do if you already found out the hard way

If you're past enrollment and you've just discovered a "ghost" listing, your options depend on how and when you enrolled.

Source: CMS Product No. 12231-P (March 2026); Medicare Advantage Open Enrollment Period and Annual Enrollment Period dates per Medicare.gov.

A quick distinction worth having straight: a grievance is a complaint about your plan's service or operations — like an inaccurate directory — and it doesn't change a specific claim decision. An appeal is a formal request asking your plan to reconsider a specific denied claim or service. If a "ghost" listing led to an actual bill you're disputing, that's an appeal. If you just want the directory itself fixed and you're weighing whether to stay in the plan, that's a grievance.

Why this matters more in a two-system market

Sioux Falls runs on two competing hospital systems, and that raises the stakes on network accuracy in a way a single-system market doesn't have to worry about. Sanford USD Medical Center carries a 5-star CMS Hospital Compare rating; Avera McKennan Hospital & University Health Center carries 4 stars — both strong, both genuinely separate networks with mostly separate physician groups.

Minnehaha County has 39,532 Medicare beneficiaries and 11 Medicare Advantage plans for 2026, according to the CMS PY2026 Medicare Advantage/Part D Landscape file — 5 standard PPOs open to anyone with Medicare, 4 Dual-Eligible Special Needs Plans, and 2 Institutional Special Needs Plans for nursing-home residents:

Source: CMS PY2026 Medicare Advantage/Part D Landscape and 2026 Star Ratings files, Minnehaha County, SD.

A plan built around the Sanford network can look identical on paper to one built around Avera — similar premium, similar star rating — until you check whether your specific cardiologist, endocrinologist, or physical therapist is actually reachable through it. Sanford Health also underwrites its own Medicare Advantage plans locally (the Align PPOs), which naturally lean toward its own network; that's a normal, disclosed business structure, not a hidden conflict, but it's one more reason a directory listing deserves a phone call rather than a glance.

None of the plans above can refuse to cover genuine emergency or urgently needed care, wherever it happens — that federal protection doesn't bend to which system your card says you're in. It's the routine, planned visits — the follow-up with a specialist, the referral to a new physical therapist — where a wrong listing actually costs you.

How we help

Checking a full list of doctors against a specific plan's real network, one phone call at a time, is exactly the kind of task most people put off — not because it's hard to understand, but because it's tedious and easy to assume someone already checked it for you. We do this as part of comparing the plans we offer against your actual doctors and prescriptions, before you enroll, not after.

If you'd rather have someone local walk through this with you, that's what we're here for. Book a conversation — no rush, and no cost to talk.

What to watch heading into 2027

1. Whether CMS-4208-F2's plan-sourced directory data actually improves accuracy once it fully replaces third-party vendor data for the CY2027 Medicare Plan Finder.
2. Whether this 2026 SEP gets extended or made permanent — CMS built it as a temporary, one-year fix; watch for updated guidance late in 2026.
3. Your 2027 Annual Notice of Change, arriving by September 30, 2026 — network changes for the year ahead show up there before anywhere else.
4. Whether Sanford or Avera adjusts which plans they're contracted with for 2027 — a network shift on either side reshuffles which plan makes sense for your specific doctors.
5. CMS's annual plan attestation deadlines under the new rule, which fall before each Annual Enrollment Period — a signal of how seriously plans are taking directory accuracy going forward.

How we know all this: Big Sioux Benefits runs every article through a data desk that cross-references CMS's own provider directory review reports, the CY2026 CMS-4208-F2 final rule, CMS's March 2026 Special Election Period notice, KFF's 2026 Medicare Advantage cost-sharing analysis, the U.S. Senate Committee on Finance's 2023 ghost network study, and the Minnehaha County Medicare Advantage plan landscape — built by Strategic AI Architects. Every figure here is sourced and dated. This is education, not legal advice; confirm your own plan's network and any enrollment options with 1-800-MEDICARE or a licensed agent. We take no payment from any carrier to feature a plan, and Big Sioux Benefits is a licensed independent insurance agency, not connected with or endorsed by the United States government or the federal Medicare program.