H.R. 5243 requires Medicare Advantage plans to provide detailed information about supplemental benefits they offer to seniors, beginning in 2029. Specifically, insurance companies must report data to the federal government showing which enrollees are eligible for various supplemental benefits, what types of benefits are offered, how often beneficiaries use them, and how much the plans spend on these benefits. Starting in October 2030, the government will make this data publicly available online and share it with researchers to help evaluate program performance and conduct health care studies, while protecting enrollees' privacy. The bill affects Medicare Advantage plans and the seniors who use them, giving patients and researchers better visibility into what supplemental benefits are available and how they're being utilized. The legislation has no specific new funding appropriation mentioned, as it primarily creates a reporting requirement for existing Medicare Advantage programs.