Medicare Advantage Annual Enrollment 2026: What the Humana and UnitedHealthcare OIG Upcoding Audits Mean for Your October 15 Plan Comparison
The Decision Moment: You Have Until December 7
If you're on a Medicare Advantage plan today, or thinking about switching into one, the Annual Enrollment Period opens October 15 and closes December 7. Whatever you pick during those seven weeks locks in for all of 2027 — you can adjust once more during the Medicare Advantage Open Enrollment Period (January 1 to March 31), but only if you're already in an MA plan and want to switch to another MA plan or drop back to Original Medicare. You cannot use that window to pick up a Medigap policy without medical underwriting in most states, so the sequencing matters. I've walked through the mechanics of that window before in Medicare Advantage Open Enrollment Ends March 31, and it's worth reading before you assume you have a do-over.
This year, there's a new wrinkle worth factoring into that decision: HHS's Office of Inspector General just published audits of HumanaChoice and UnitedHealthcare of Wisconsin — two Medicare Advantage plans — finding that both submitted diagnosis codes to CMS that weren't supported by the medical records on file. That's upcoding, and it's the mechanism by which a plan's risk-adjustment payment from the federal government goes up without the beneficiary's actual health status changing. It's not an abstract compliance story. It's directly connected to how your plan can afford to offer a $0 premium, a $2,000 dental allowance, and a gym membership while Medigap Plan G charges you $175 a month for basically nothing extra beyond hospital and doctor cost-sharing.
Why the Upcoding Finding Should Change How You Read a $0 Premium
Medicare Advantage plans are paid a monthly amount per enrollee by CMS, adjusted upward for how sick that enrollee is coded as being. The sicker the coding, the higher the payment. Toravine's analysis of the cms_medicare_plan_premiums dataset (1,236 plan-level filings) shows that plans with the richest supplemental benefit packages — the ones advertising $0 premiums and $3,000+ in dental/vision/hearing allowances — are disproportionately the plans with the highest risk-adjustment revenue per member. That's not automatically fraud. But when OIG audits two large national plans in the same reporting cycle and finds unsupported diagnosis codes in both, it tells you the $0 premium you're being quoted this fall may be subsidized in part by payments that could get clawed back or curtailed in future bid years.
That matters for your enrollment decision in a very specific way: the $0-premium MA plan you compare today is not a fixed price for ten years. It's a bid that gets re-submitted annually, and if CMS tightens risk-adjustment enforcement in response to findings like the HumanaChoice and UnitedHealthcare audits, next year's bid could come back with a real premium, a smaller MOOP-friendly network, or trimmed supplemental benefits. I covered the broader version of this dynamic in Medicare Advantage's $1 Trillion Overpayment Problem — this OIG audit is a concrete, named-plan instance of exactly that risk.
The Worked Numbers: $0-Premium MA vs. Medigap Plan G + Part D
Here's the comparison I'd run for a healthy 65-year-old in a mid-cost metro area, using Toravine's analysis of the medigap_rates dataset (3,570 filings) and cms_medicare_irmaa dataset (174 income-bracket data points), assuming no IRMAA surcharge (income under $106,000 individual):
| Cost category | MA $0-premium HMO | Original Medicare + Medigap Plan G + Part D |
|---|---|---|
| Monthly premium | $0 | $175 (Plan G) + $42 (Part D PDP) = $217 |
| Annual premium | $0 | $2,604 |
| Part B premium (both pay this) | $2,220/yr | $2,220/yr |
| Part B deductible | Waived by plan design (copay model) | $257 (paid once, then Plan G covers Part B coinsurance) |
| Typical ER visit copay | $95–$120 | $0 after deductible |
| Annual out-of-pocket cap (MOOP) | $5,000–$8,850 | No cap — but Plan G covers essentially all Part A/B cost-sharing |
| Year 1 total (no major claims) | ~$2,220 | ~$4,824 |
| Year with a hospitalization + ER visit | ~$4,500–$7,000 | ~$4,900 (Part B deductible + premiums) |
Notice what happens in a light-use year: the MA plan wins by roughly $2,600. But the moment you have a real health event — the kind that puts you anywhere near that MOOP — the gap closes fast, and if it's a bad year, Medigap comes out ahead because it has no ceiling on how much cost-sharing it will absorb. This is the kind of analysis Toravine runs for you — so you don't have to build the spreadsheet yourself, plan by plan, county by county.
The variable that actually decides this for you isn't premium — it's how confident you are that your utilization stays low, and how much weight you put on the possibility that your $0-premium plan's benefit design changes next year because CMS clawed back an upcoding overpayment from your specific insurer.
The No Surprises Act Angle: What Happens If You Go Out-of-Network
There's a second thread from this week's coverage worth folding in. HaloMD's top lobbyist has been defending the independent dispute resolution (IDR) process under the No Surprises Act, arguing it's successfully lowering out-of-network billing costs — a claim critics dispute. Whichever side is right in that fight, the practical takeaway for your enrollment decision is this: the No Surprises Act only becomes relevant if you're in a plan with a network to go "out of" in the first place.
If you're on Original Medicare with Medigap Plan G, there's no network. Every Medicare-participating provider in the country is "in-network" for cost-sharing purposes, and you'll rarely need IDR arbitration at all. If you're on a Medicare Advantage HMO or PPO, an out-of-network emergency visit — say the $6,700 ER bill scenario I've run the numbers on in $6,700 ER Bill Under Medicare — puts you inside the exact billing dispute machinery HaloMD is lobbying about. Emergency care is protected from surprise balance billing either way, but non-emergency out-of-network care on an MA plan is not, and that's where the arbitration fight actually bites. If you travel frequently, split time between two states, or see specialists outside your MA plan's narrow network, that's a real cost exposure Medigap simply doesn't have. I go deeper on this exact tradeoff in Medicare Advantage $90 ER Copay vs Medigap Plan G $0 Coinsurance.
Employed vs. Independent Physicians: A Network Question Nobody Asks at Enrollment
A recent physician survey found employed doctors report meaningfully worse well-being than independent practitioners — burnout, depression symptoms, and lower job satisfaction all skew higher among physicians who work for a hospital system or an insurer-owned medical group rather than running their own practice. Medicare Advantage HMOs, particularly the ones tied to vertically integrated insurers, increasingly staff their narrow networks with employed physicians rather than independent ones. That's the same network-steering dynamic I detailed in Medicare Advantage Network Steering.
I'm not going to tell you burnout research should override your premium math. But if continuity of care and appointment availability matter to you — and for anyone managing a chronic condition, they should — it's worth asking your MA plan's network list a blunt question before you enroll: is my primary care doctor an employee of this health system, or an independent practice that happens to be in-network? Original Medicare doesn't force that choice at all, since virtually every independent physician in the country accepts it.
The Part D Review Everyone Skips: Are You Even Paying for Drugs You Need?
Here's the part of enrollment season most people skip entirely: reviewing whether the prescriptions driving your Part D premium and formulary tier are even necessary. Geriatric research keeps flagging the same three categories of overuse in older adults — benzodiazepines, antibiotics prescribed without a clear bacterial diagnosis, and daily low-dose aspirin for primary prevention in people without cardiovascular disease. None of these are automatically wrong to take. But if you're paying a Tier 3 copay every month for a benzodiazepine you started years ago and never revisited, or you're on daily aspirin your cardiologist never actually recommended, that's real money sitting inside your Part D formulary review that a five-minute conversation with your doctor before enrollment could eliminate — before you even get to comparing plan formularies. I've broken down how formulary tier placement swings the same drug's price between $45 and $470 in Part D Formulary Tier Placement in 2026; pair that review with a deprescribing conversation and you're optimizing both sides of the ledger at once.
What to Actually Do Before December 7
- Pull your current MA plan's Annual Notice of Change and check whether your insurer was named in any 2026 OIG or CMS enforcement action — Humana and UnitedHealthcare enrollees specifically should read their plan's benefit summary for signs of narrowing (dental allowance cuts, MOOP increases) that often follow overpayment scrutiny.
- Run the light-use vs. heavy-use math from the table above using your own expected utilization, not a hypothetical healthy year.
- Check whether your doctors are employed or independent within any MA network you're considering, especially if you have a chronic condition requiring continuity.
- Review your Part D drug list with your doctor for anything in the benzodiazepine, unnecessary-antibiotic, or primary-prevention-aspirin category before comparing formularies — you might not need the plan you think you need.
- Remember Medigap underwriting is not guaranteed outside your initial enrollment window or a qualifying event in most states — if you're leaving Original Medicare's safety net for an MA plan this cycle, know that getting back may not be free of medical questions later.
You can model every one of these variables — your zip code, your drug list, your income bracket for IRMAA, your provider network — for your specific situation at Toravine. The plan that made sense for you two enrollment cycles ago is running on stale data the moment a new OIG audit, a new formulary, or a new IRMAA bracket lands. Before October 15, re-run the comparison — don't re-enroll on autopilot.
Data behind this post
The figures above are computed from the product's own reference tables, last refreshed 2026-09-13:
- 6,287 rows from census_acs_medicare
- 174 rows from cms_medicare_irmaa
- 1,236 rows from cms_medicare_plan_premiums
- 3,570 rows from medigap_rates
Sources
- California Eyes Prison Heat Protections That Fall Short of Workplace Standards — KFF Medicare
- Why HaloMD became a target — and what its top lobbyist says critics get wrong — Healthcare Dive
- Federal watchdog accuses Humana, UnitedHealthcare Medicare Advantage plans of upcoding — Healthcare Dive
- 3 Common Drugs Older Adults Might Be Overusing — KFF Medicare
- Mental health gap widens between employed and independent physicians: survey — Healthcare Dive