Medicare, the United States’ federal health insurance program, primarily covers individuals 65 and older, as well as certain younger people with disabilities or chronic diseases. Understanding how Medicare is financed is crucial for comprehending its sustainability and potential future changes. The program relies on a multifaceted funding structure, drawing from general revenues, payroll taxes, premiums paid by beneficiaries, and other sources. Part A, Hospital Insurance, is mainly financed through payroll taxes. A 2.9% tax is levied on wages and self-employment income, split equally between employers and employees (1.45% each). High-income earners are subject to an additional 0.9% Medicare tax on earnings exceeding $200,000 for individual filers and $250,000 for joint filers. These payroll taxes are deposited into the Hospital Insurance (HI) Trust Fund. This fund is dedicated solely to paying for Part A benefits, which include inpatient hospital care, skilled nursing facility care, hospice care, and some home healthcare services. The solvency of the HI Trust Fund is regularly evaluated, and projections inform policy debates about potential adjustments to maintain its long-term stability. Part B, Medical Insurance, which covers physician services, outpatient care, preventive services, and some home healthcare, is financed differently. A significant portion comes from general revenues of the U.S. Treasury. This means that income taxes, corporate taxes, and other federal revenue sources contribute to funding Part B. The remaining portion is covered by monthly premiums paid by beneficiaries enrolled in Part B. Generally, the standard monthly premium is adjusted annually based on healthcare costs. However, higher-income beneficiaries pay higher premiums based on their income levels. This tiered premium structure aims to make Medicare more equitable. Part C, also known as Medicare Advantage, is an optional program that allows beneficiaries to receive their Medicare benefits through private health insurance plans. These plans are contracted with Medicare to provide Part A and Part B benefits, and often include Part D (prescription drug) coverage. Medicare Advantage plans receive a per-member, per-month payment from the Medicare program. These payments are risk-adjusted to account for the health status of the enrollees. The funding for Part C comes from a combination of the HI Trust Fund (for Part A-related services) and general revenues and beneficiary premiums (for Part B-related services). Part D, the Prescription Drug benefit, is also financed through a combination of general revenues, beneficiary premiums, and state payments. Beneficiaries pay monthly premiums for their Part D plans, and these premiums vary depending on the plan chosen. General revenues from the U.S. Treasury cover a substantial portion of the program’s costs. Additionally, states contribute to the cost of Part D through a “clawback” provision, which requires them to pay a portion of the costs for individuals who are dually eligible for Medicare and Medicaid. In summary, Medicare’s financial health depends on a complex interaction of payroll taxes, general revenues, premiums, and state contributions. Each part of Medicare is funded through distinct mechanisms, creating a system that balances government funding with contributions from beneficiaries and taxpayers. The ongoing debates surrounding Medicare reform frequently center on adjusting these funding streams to ensure the program’s long-term solvency and ability to provide affordable and accessible healthcare to its beneficiaries.