This bill requires Medicare Advantage insurance plans to report detailed data about the supplemental benefits they offer to enrollees, starting with plan years beginning January 1, 2027. Supplemental benefits are additional services and items that Medicare Advantage plans can provide beyond standard Medicare coverage, such as dental care, vision services, or transportation. The bill mandates that plans submit information to the government about which enrollees are eligible for these benefits, what types of benefits are offered, how much the benefits are actually used, and how much the plans spend on them for each enrollee. Beginning in October 2028, the government must make this data publicly available online and to researchers so that patients and health care analysts can better understand what supplemental benefits different plans provide and how they are being used. The bill includes privacy protections to ensure that individual enrollee information remains confidential when data is released to the public.