Relative effects of changes on the Medicare Hospital Insurance Trust Fund's actuarial balance by decade, 1985-2024. Source: Authors' analysis of Medicare Trustees Reports, 1985-2024. Published reports in 1980-1984 and 1989 did not quantify impacts of major contributors to annual changes in the 75-year actuarial balance. The value of the Medicare Hospital Insurance Trust Fund's actuarial balance is measured as a percent of the annually projected 75-year taxable payroll. Bars indicate the unweighted cumulative percent point of change on the actuarial balance resulting from changes due to either implemented legislative policy measures or changes in key assumptions of the Trustees.