Every year from October 15 to December 7, Medicare beneficiaries can switch Medicare Advantage plans, change Part D coverage, or move between Medicare Advantage and Original Medicare. Every change takes effect on January 1.
For patients, open enrollment is a shopping decision. For practices, it is a silent data change that shows up weeks later as a rejected claim. This year, that change is going to be larger than usual.
Insurers are pulling back from Medicare Advantage at a pace the market has not seen in years. Humana has said its 2027 plan exits will affect roughly 600,000 members, and Becker’s has reported at least four insurers exiting Medicare Advantage markets for 2027, including Humana and Molina.
That follows a disruptive 2026. A JAMA study published in February found that about 1 in 10 Medicare Advantage enrollees, roughly 2.9 million people, were forced out of their plans this year when those plans left the market.
Provider networks are shifting from the other direction too. Becker’s has tracked roughly 90 hospitals and health systems that have ended some or all of their Medicare Advantage contracts over the past three years, with at least 15 doing so in 2026 alone.
Patients whose plans are ending also get extra time. In addition to the regular enrollment window, they have a special enrollment period that runs through the end of February. That means coverage changes will keep trickling in well past January 1.
For oncology and pain management practices, the timing is especially unkind. Patients in the middle of an infusion schedule, a radiation course, or an injection series do not pause treatment for a coverage transition.
Eligibility on file goes stale overnight. A patient seen in December under one plan may arrive in January with a different plan, or with Original Medicare after a plan exit, and never mention it. Claims go to the wrong payer, bounce back, and restart the clock on timely filing.
Authorizations do not automatically follow the patient. An approval from a terminated plan is not a blank check with the new one. Without a plan for transition, staff end up requesting authorizations after services have already been scheduled or delivered.
Network status changes without warning. A patient who switches plans may land somewhere your practice is out of network. If nobody catches it before the visit, the practice is left with a denial and a patient who expected to be covered.
Patient responsibility resets. Deductibles restart on January 1, and Part D costs are rising. The Part D out-of-pocket cap increases from $2,100 to $2,400 in 2027, and the maximum deductible moves from $615 to $700. Oncology patients on oral therapies can reach that cap quickly, so the financial conversation needs to happen early in the year rather than at the pharmacy counter.
Federal rules give practices one important protection. Under 42 CFR 422.112(b)(8), Medicare Advantage coordinated care plans must provide a transition period of at least 90 days when a patient in an active course of treatment switches to a new plan. During that window, the new plan cannot require prior authorization for the treatment already underway.
Three details matter here. The protection applies to an active course of treatment, so documentation of when that course started and what it includes is essential. It applies when a patient moves into a new Medicare Advantage plan, not to every coverage scenario. And once the 90 days end, the plan can reassess medical necessity and apply its normal authorization and network rules.
In other words, the rule buys time. It does not replace the work. Practices that treat the 90 days as a runway to secure new authorizations come through January cleanly. Practices that treat it as a reprieve hit the same wall in April.
Commercial patients may have similar protection. As we covered in [our post on the prior authorization pledge], participating health plans committed to honoring existing authorizations for 90 days when a patient changes plans.
Ask every Medicare patient about their coverage before they leave. A simple question at checkout in November and December (“Are you changing plans for next year?”) surfaces changes weeks before they become denials. If a patient mentions a non-renewal letter, note it in the account.
Build a list of patients in active treatment. Identify every patient whose treatment will cross January 1, along with their current authorizations and treatment start dates. Those are the accounts where a missed coverage change costs the most.
Re-verify everyone in January, not just new patients. Run eligibility on every returning patient’s first visit of the year. This is the single highest-return front-end task in the first quarter.
Line up new authorizations early. For patients switching plans mid-treatment, use the 90-day transition window to obtain authorizations from the new plan before it closes.
Update patient estimates for the new year. Refresh deductible and cost-sharing assumptions, and for Part D patients on high-cost drugs, mention the Medicare Prescription Payment Plan, which lets patients spread out-of-pocket drug costs across the year.
Watch your first 30 days of denials by payer. A spike in eligibility or registration denials in January is an early warning. The [denial prevention framework we outlined in July] applies directly here: catch the pattern at the front end rather than working it on the back end.
Medicaid patients are facing their own January 1 changes as well. If your practice serves both populations, [our breakdown of the OBBBA Medicaid eligibility provisions] covers what is changing on that side.
Open enrollment is a patient decision, but the revenue impact belongs to the practice. The organizations that finish the first quarter strong will be the ones that did the verification work in November and December instead of the rework in February.
If you want a second set of eyes on your January readiness, or help identifying which patients carry the most coverage risk heading into the new year, schedule a discovery call or book a free audit with Pollux Systems.
