CareFirst BlueCross BlueShield is suing CMS over its 2026 Medicare Advantage star ratings, alleging improper calculations cost the insurer an estimated $32 million in quality bonus payments.
The lawsuit, filed Jan. 20 in the U.S. District Court for the District of Columbia, claims CMS departed from its own guidance when it used corrected patient safety data released after the close of the plan preview period to calculate star ratings, resulting in CareFirst receiving a 3.5-star rating instead of 4 stars for a contract covering approximately 30,000 Medicare beneficiaries in Maryland.
At the center of the dispute is the Drug Plan Quality Improvement Measure, which compares a plan’s performance between two years to determine whether it achieved “significant improvement.” CareFirst alleges that CMS’s contractor, Acumen, released final patient safety reports in July 2024 as required by agency guidance, but then quietly replaced those reports with corrected data on Sept. 30, 2024, more than two weeks after the second plan preview period had closed.
According to the complaint, the September 2024 correction made a small change to one plan member’s medication adherence data, which slightly raised CareFirst’s baseline score and reduced the improvement the insurer could demonstrate the following year. CareFirst says it missed the 4-star threshold by a “statistically insignificant margin” as a result.
CareFirst alleges Acumen downplayed the significance of the correction in an email to plans, and that CMS took no steps to clarify the changes or explain its departure from prior guidance. The insurer said it raised the issue with CMS during the 2026 star rating preview period, but the agency declined to adjust the rating.
CareFirst is asking the court to set aside the 2026 star rating, order CMS to recalculate the rating by excluding the medication adherence measure from the Drug Plan Quality Improvement calculation, and apply the corrected rating to its 2027 quality bonus payment.
The lawsuit is the latest in a growing wave of litigation from insurers challenging how CMS calculates MA star ratings. UnitedHealthcare, Humana, Elevance, Alignment Health, Centene, SCAN Health Plan, Louisiana Blue, Florida Blue, and BCBS Massachusetts have all filed legal challenges over star ratings in recent years, with differing results. UnitedHealthcare, Centene, SCAN and Alignment have prevailed in their challenges, while courts have ruled against Elevance, Humana, and all three BCBS plans. Humana has appealed its dismissal.
