Medicare open enrollment for 2027 runs from October 15 to December 7, 2026, and every change a patient makes in it takes effect on January 1. For a small practice the season is not about choosing plans; that is the patient's decision. It is about the first two weeks of January, when a share of your Medicare patients arrive with coverage that changed without anyone telling you, and about the window that stays open until March 31. The front desk that re-verifies at the first visit after January 1 avoids most of the denials that open enrollment produces. The one that trusts the card on file finds them in February.
In short
- October 15 to December 7, 2026: open enrollment. Changes take effect January 1 (Medicare.gov).
- January 1 to March 31, 2027: a patient already in Medicare Advantage can make one more change, effective the first of the following month (CMS, 2026).
- 55% of eligible Medicare beneficiaries, 35.2 million people, are in Medicare Advantage in 2026, and 34% of Michigan's Medicare Advantage enrollees are in employer or union group plans (KFF, 2026).
- Humana expects its 2027 plan exits to affect roughly 600,000 members, about 8% of its Medicare Advantage membership (Healthcare Dive, 2026).
Why the card on file is wrong in January
Medicare coverage for 2027 can change in more windows than most offices track. CMS lists them in its enrollment periods fact sheet, and each one moves a patient's coverage on a different date.
| Window | Who it applies to | Change takes effect |
|---|---|---|
| October 15 to December 7 | Anyone with Medicare | January 1 |
| January 1 to March 31 | People already in Medicare Advantage, one change | First of the next month |
| December 8 to end of February | People whose Medicare Advantage plan did not renew | Varies; Original Medicare if they do nothing |
| Any month | People with Medicaid or Extra Help, once a month | First of the next month |
| December 8 to November 30 | Joining a five-star plan, once | Varies |
The third row is the one that catches practices. CMS states that a person whose plan does not renew "will be enrolled in Original Medicare" if they do not join another Medicare Advantage plan. A patient who ignored the letter from their plan still has Medicare in January. They no longer have the plan whose card you scanned last spring.
Plan exits are not hypothetical this year. Healthcare Dive reported on July 29, 2026 that Humana "expects the exits will impact roughly 600,000 seniors," about 8% of its 7.2 million Medicare Advantage members. The report does not name states, and nothing here says which Michigan counties are affected; the patient's own Annual Notice of Change, which Medicare.gov says plans send in September, is where that shows up.
Six checks for the front desk, in order
- Put a note on every Medicare Advantage chart now. Ask at every visit between October 15 and December 7 whether the patient has received an Annual Notice of Change and whether they plan to switch. You are not advising; you are recording what they tell you.
- Tell patients to bring the new card in January. A sentence in the reminder text for any appointment after January 1 is enough: "If your Medicare plan changed for 2027, please bring your new card."
- Re-verify eligibility at the first visit after January 1. Not the card, the eligibility response. The card in the wallet may be last year's.
- Re-verify again for visits through March 31. CMS allows one Medicare Advantage change between January 1 and March 31, effective the first of the next month. A patient verified on January 10 can be on a different plan on March 1.
- Flag patients with Medicaid or Extra Help separately. They can change plans once a calendar month. For them, verification is a monthly job, not a January one.
- Refer plan questions to MMAP, not to staff. The Michigan Medicare/Medicaid Assistance Program is a free counselling service on 1-800-803-7174. Your staff can say whether the practice takes a plan. They should not tell a patient which plan to choose.
The mistake most practices make at step 3
They verify in January and stop. The second window is the reason denials from Medicare Advantage keep arriving into the spring. A patient who switched from one Medicare Advantage plan to another on February 15 is on the new plan from March 1, and a verification dated January 10 says nothing about it. Verify at each visit through the end of March, and the problem goes away.
What is different in Michigan
Group plans are a larger share here than almost anywhere. KFF reports that group enrollees make up 34% of Medicare Advantage enrollees in Michigan, one of seven states where the share is a quarter or more. Those are retirees whose coverage comes through a former employer or union, and their plan decisions do not always follow the individual open enrollment calendar. When a retiree says "nothing changed, it's through my old job," verify anyway.
Market concentration matters too. KFF puts UnitedHealth Group and Humana together at 46% of all Medicare Advantage enrollees nationwide. When one of the two largest carriers trims plans, a practice's Medicare panel feels it even if the practice never contracted differently.
What changes in the patient's costs
Some of what patients ask the front desk about in October is drug coverage. CMS set the 2027 Part D base beneficiary premium at $41.33 and said it will discontinue the Part D premium stabilisation demonstration at the end of 2026. The base premium is a figure used in the calculation, not the price of any plan, and CMS said it would release the 2027 plan landscape in mid to late September. If a patient asks what their plan will cost, the answer is their Annual Notice of Change or MMAP, not the practice.
Where this sits in the rest of the year
Open enrollment is the Medicare half of a heavy autumn for the insurance desk. The Healthy Michigan Plan work requirements guide covers the Medicaid half, where six-month renewals start in 2027, and the 2027 physician fee schedule guide covers what Medicare will pay once the plan is right. For a practice, the part we build is the intake before the visit: forms sent by text, insurance cards photographed and filed before the patient arrives, and a desk that answers "do you take my plan" from the list the office keeps. We never guess at coverage or advise on a plan; the verification stays with the office.
The patient chooses the plan in December. The practice finds out in January, or in February from a denial.
