The Income-Related Monthly Adjustment Amount (IRMAA) is an extra cost added to Medicare Part B and Part D premiums for higher-income individuals. It is based on Modified Adjusted Gross Income (MAGI) from two years prior, meaning 2026 IRMAA brackets will be determined by 2024 tax returns. IRMAA increases Medicare costs in tiered brackets, so individuals with higher incomes pay more in ... https://www.federalpensionadvisors.com/post/2025-irmaa-brackets