What is the Income-Related Monthly Adjustment Amount (IRMAA)?

IRMAA stands for Income-Related Monthly Adjustment Amount and is a surcharge added to your Medicare Part B (medical insurance) and Part D (prescription drug coverage) premiums if your Modified Adjusted Gross Income (MAGI) exceeds a certain threshold. The surcharge is determined by the Social Security Administration (SSA) based on income reported to the IRS from the prior two tax years.