Primary care doctors with Mass General Brigham Medical Group Western Massachusetts, the practice group formerly known as Cooley Dickinson Medical Group, left Blue Cross Medicare Advantage networks on Oct. 1. A 90-day transition period for their patients runs through Dec. 31, and Medicare’s fall enrollment window closes Dec. 7.
The rules differ by plan type. Mass General Brigham says Blue Cross Medicare Advantage HMO members will get specialty care but no primary care at those practices. PPO members can still see the primary care doctors, at a higher share of the cost.
The change reaches only the primary care side. Mass General Brigham specialists and hospitals, Cooley Dickinson Hospital among them, stay in network for Blue Cross Medicare Advantage, and the primary care doctors remain in Blue Cross commercial networks. A member can therefore keep a cardiologist or surgeon and still lose the family doctor who coordinates everything.
The member who has to act is the Blue Cross Medicare Advantage patient with a regular primary care appointment at one of these practices. There are two separate jobs: ask Blue Cross for continuity of care now, and decide before Dec. 7 whether to stay with Blue Cross for 2027 or move to a plan that includes the practice.
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HMO or PPO: the card decides what happens next
Mass General Brigham’s page on the Blue Cross change says the primary care providers “will no longer be in-network in Blue Cross’ Medicare Advantage PPO and HMO networks.” The page does not name the specific Blue Cross plans, so the plan name and type on the member ID card are what count.
An HMO member has the harder problem. With no primary care available at the practice after the transition, that member needs a new primary care doctor inside the network. A PPO member has a choice: pay the higher cost share to stay, or look elsewhere.
How to request more time with the same doctor
During the 90-day transition, Blue Cross Medicare Advantage members can ask to keep seeing their current primary care provider. The hospital system says the way to start is a continuity of care form or a call to the number on the back of the member ID card.
For requests that are approved, the page says members keep the in-network cost-sharing rate, with “no change in cost” during the window. Approval is not automatic, so a member who has not filed should do so before scheduling the next visit, and should ask what end date appears on the approval.
The Dec. 31 end date is not the Dec. 7 deadline
Two dates are in play, and they point in different directions. Dec. 7 is the last day of the annual enrollment period, which began Oct. 15, and plan changes made by then start Jan. 1, 2027. Dec. 31 is when the transition care ends, so a member who stays with Blue Cross for 2027 meets the out-of-network rules for these practices on Jan. 1.
The system also lists a second chance. The Medicare Advantage open enrollment period, Jan. 1 through March 31, 2027, lets a member change plans once. Waiting for it means starting 2027 in a plan that may not include the practice.
Which 2027 plans include the practice
For 2027, Mass General Brigham lists three Medicare Advantage options in western Massachusetts that include its primary care: Health New England, Tufts Medicare Preferred and UnitedHealthcare. It also lists Original Medicare with a supplemental plan. Medicare’s Plan Finder shows which of them are sold at a member’s ZIP code and what each costs.
Moving to Original Medicare brings Medigap into play. Medicare.gov explains that a guaranteed right to buy a Medigap policy applies in certain situations, within 60 days before to 63 days after Advantage coverage ends, and that outside them no federal guarantee exists. In Iowa, a state Insurance Division release says members of canceled plans can move to Original Medicare without medical underwriting. A doctor-group exit is not a plan cancellation, and Mass General Brigham’s page does not describe such a right for this change.
Phone numbers for the switch
Mass General Brigham’s Patient Insurance Resource Center, at 800-953-1680, answers plan questions and can connect a patient with a licensed insurance representative. After enrolling in a new plan, patients can update their insurance in Patient Gateway or call the registration team at 866-211-6588.
Express Care sites in Amherst, Greenfield, Northampton and Southampton remain available, and emergency care is covered at all Mass General Brigham locations regardless of insurance, according to the system.
Where will primary care come from after Dec. 31?
The transition date, not the Oct. 1 exit, is the one that sets the deadline for the family doctor’s office.
A Blue Cross member who waits until the transition period ends can find the primary care office out of network or at a higher cost share, with the fall window already closed. A switch picked from a plan name alone can repeat the problem if the new plan does not list the practice.
The 2027 Medicare Open Enrollment Decision Kit is built for this decision. It includes a cost calculator spreadsheet that compares plans on cost, drugs and doctors, a provider call script for confirming that a doctor is in network, a prescription-by-plan comparison and the Open Enrollment calendar.
This article was produced with AI assistance and edited for accuracy against the sources linked above.
David M. Keller is a finance writer based in Columbus, Ohio, covering personal finance and consumer-focused economic topics. He earned his degree in journalism from Ohio University and began his career reporting on local business and economic trends for a regional media outlet. Since then, he has contributed to a variety of online publications, focusing on clear, practical coverage of topics such as cost of living, debt, and everyday financial decision-making.
