Medicare Part B premiums determined by program costs, not Social Security benefits

Medicare Part B premiums are not calculated as a percentage of an individual's Social Security benefits. Instead, these premiums are set annually in October by the Centers for Medicare and Medicaid Services (CMS) based on the anticipated total costs of the Medicare program for the following year.

Generally, Medicare Part B premiums are expected to offset approximately 25% of CMS's anticipated total program costs, with the federal government covering the remainder. For 2026, the standard Part B premium is $202.90.

Premium amounts may vary from the standard rate based on specific provisions. The "hold harmless provision" protects lower-income seniors by ensuring monthly Social Security benefits do not decrease due to premium increases. Conversely, the Income-Related Monthly Adjustment Amount (IRMAA) applies to individuals with higher provisional incomes, requiring them to pay a supplemental amount on top of the standard premium.