Medicare open enrollment opened on Sunday, October 15, and runs through December 7, 2023. Between now and then, roughly 65 million Medicare beneficiaries will be invited to reconsider their coverage, and a meaningful share of them will change plans effective January 1, 2024. For a practice, that means the insurance card a patient hands over in January is, more often than in any other month, not the one on file.
This year the backdrop is different. In August, KFF reported that 30.8 million people, or 51% of the eligible Medicare population, are enrolled in Medicare Advantage plans in 2023. It is the first time in the program's history that Advantage plans cover a majority. The average beneficiary can choose among 43 Advantage plans. The shift from traditional Medicare to private plans has been steady for two decades, but crossing half changes how a practice should think about its "Medicare" patients.
Key takeaways
- More than half of eligible Medicare beneficiaries are now in Advantage plans, so a practice's "Medicare" book is, operationally, dozens of commercial-style payers with older patients.
- CMS-4201-F takes effect January 1, 2024: Advantage plans must follow Medicare coverage rules, honor approved authorizations for the course of treatment, and give new enrollees a 90-day transition on active treatment.
- January's problems are predictable: claims to last year's plan, authorizations that did not move with the patient, and deductible surprises. A December eligibility sweep prevents most of them.
- The 2024 Part B deductible is $240 and the standard premium is $174.70, announced by CMS on October 12. Load the deductible into estimate tools before January 1.
Why the majority matters to a practice
Traditional Medicare is one payer with one set of rules, one enrollment, national coverage determinations and predictable payment timelines. Medicare Advantage is dozens of payers, each with its own network, prior authorization list, claims address, appeal process and, often, its own fee schedule expressed as a percentage of Medicare. A practice where 60% of Medicare-age patients are now on Advantage plans is, operationally, a commercial practice with older patients. The billing team needs to be built for that.
| Area | Traditional Medicare | Medicare Advantage |
|---|---|---|
| Eligibility | One eligibility check; coverage rarely changes mid-year | Plan can change each January; supplemental benefits vary by plan |
| Prior authorization | Very limited | Common for imaging, procedures, DME, post-acute care |
| Payment timeline | Typically 14 to 30 days for clean electronic claims | Varies by plan; prompt-pay rules apply as for commercial plans |
| Enrollment | PECOS | Separate credentialing and contracting with each plan |
| Coverage rules | NCDs and LCDs | Must follow NCDs and LCDs from January 1, 2024 under CMS-4201-F; plan criteria allowed only where Medicare rules are not fully established |
| Patient cost sharing | Part B deductible ($240 in 2024) then 20% coinsurance, often covered by a supplement | Plan-specific copays and deductibles; out-of-pocket maximum applies |
What CMS-4201-F changes on January 1
The Medicare Advantage and Part D final rule CMS issued on April 5, 2023 (CMS-4201-F) takes effect for the 2024 contract year. Three provisions matter directly to practices:
- Coverage criteria. Advantage plans must follow traditional Medicare's national and local coverage determinations. They may apply their own internal criteria only where Medicare coverage rules are not fully established, and those criteria must be publicly accessible and based on current evidence.
- Authorization validity. An approved prior authorization must remain valid for as long as medically necessary to avoid disruption of care, and plans must provide a minimum 90-day transition period during which a new enrollee's active course of treatment cannot be subjected to a fresh authorization requirement.
- Purpose of prior authorization. Plans may use prior authorization only to confirm diagnoses or medical criteria and to ensure that a service is medically necessary, not to delay or discourage care. Plans must also establish a utilization management committee to review their policies annually.
The 90-day transition rule is the one to watch in January. A patient who switches Advantage plans effective January 1 while in the middle of physical therapy, chemotherapy or a planned surgical sequence should not be required to start authorization over with the new plan for 90 days. In our experience, payer systems do not always reflect a new rule on the day it takes effect, so the practice needs to know the rule well enough to cite it when a denial arrives.
The coverage criteria provision matters for appeals. Today, an Advantage plan denial that cites the plan's own clinical policy for a service Medicare covers under an NCD or LCD is hard to fight. From January 1, the appeal writes itself: the plan is required to follow the Medicare determination, and the letter quotes it. Denial management teams should keep the relevant NCD and LCD numbers for the practice's common procedures on hand for exactly this.
What January looks like at the front desk
Every January we see the same three problems. Claims sent to last year's plan because nobody asked for the new card. Services rendered under an authorization from the old plan without telling the new one. And patients surprised by new copays, new deductibles and new network restrictions they did not understand when they enrolled.
The fix is a front-end routine that starts now and peaks in the first two weeks of January.
- Re-verify every Medicare-age patient at scheduling for January dates. Run eligibility electronically (the 270/271 transaction) in the last week of December for the first two weeks of January appointments, and again at check-in. A patient whose 271 shows a new payer gets flagged before the visit.
- Ask for the card every visit in January and February. Not "has anything changed", which invites no. "May I see your insurance card" produces the new card.
- Review open authorizations for patients whose plan changed. Pull authorizations with dates spanning January 1 and check the patient's January eligibility. Cite the 90-day transition provision with the new plan where it applies.
- Update the authorization matrix. Each Advantage plan has its own list. If your patients are moving to a plan the practice sees rarely, someone has to learn its rules before the first visit.
- Prepare the financial conversation. January deductible resets and new plan cost sharing are the source of most patient billing complaints in the first quarter. Estimates at check-in prevent statements in March that nobody expected.
A worked example: what plan switching costs when nobody checks
Consider a two-physician internal medicine practice with 1,100 Medicare-age patients, 640 of them on Advantage plans. If 8% of the Advantage patients switch plans at open enrollment, a common range in our experience, that is about 51 patients whose January claims go to the wrong payer unless someone catches the change. At an average of $160 per visit and one visit each in the first quarter, roughly $8,200 in claims is denied for wrong payer or member not found, then rebilled after the correct plan is identified, typically 30 to 45 days late. Add the handful of those patients mid-treatment whose authorizations did not transfer, and the first quarter's over-60 AR for Medicare Advantage doubles for reasons that have nothing to do with the care provided.
The December eligibility sweep that prevents this takes one staff member about a day for a practice this size, using batch 270 transactions through the clearinghouse. It is the best-paid day of the year.
Network and enrollment
If patients are moving to an Advantage plan the practice is not contracted with, the practice has a decision to make before January, not after. Enrollment with a new plan can take 60 to 120 days. A practice that discovers in January that 40 patients moved to a plan it does not participate in will spend the first quarter either referring those patients out or seeing them out of network. The credentialing team should be asked now which plans in the market the practice does not hold contracts with, and whether the plan's local enrollment is growing.
The reverse question matters too. Plans sometimes drop practices or change networks for the new year, and the notice goes to whatever address the plan has on file. Confirm participation status in writing with every Advantage plan the practice bills, so that a network change surfaces in November rather than in a January denial.
Questions we hear
Should we encourage patients to stay in traditional Medicare?
Plan choice is the patient's and their advisor's decision, and practice staff should not steer it. What staff can do is tell patients which plans the practice participates in, so nobody enrolls in a plan expecting to keep a physician who is out of network.
Do the CMS-4201-F rules apply to commercial plans?
No. They apply to Medicare Advantage. Commercial prior authorization is governed by state law and contract, and the recent voluntary reductions by UnitedHealthcare and Cigna are business decisions, not regulation.
What about the Part B premium and deductible for 2024?
CMS announced them on October 12. The standard Part B premium rises to $174.70 a month from $164.90, and the annual Part B deductible rises to $240 from $226. The front desk needs the $240 figure loaded in the estimate tool before January 1 so estimates for traditional Medicare patients without a supplement are right on the first visit of the year.
What to do this month
- Pull the practice's Medicare-age patients by current plan and compare the list to the Advantage plans marketed heavily in your county this fall.
- Confirm participation status and effective enrollment in writing with every Advantage plan your patients hold or are likely to move to.
- Schedule the December eligibility sweep and the January card routine with the front desk, and put the 90-day transition rule on a one-page reference sheet.
- Update the estimate tool with the 2024 Part B deductible of $240 and the January deductible reset script.
- Brief providers and the denial team that Advantage plans must follow Medicare coverage rules from January 1, so a denial that cites plan criteria where an NCD or LCD exists is appealable on that basis.
