Medicare Part D IRMAA
Unlike a Medicare Part D penalty for waiting too long to enroll, IRMAA is an extra amount you pay for Part D coverage in addition to your Medicare Part D premium that is solely based on your income.
If your modified adjusted gross income as reported on your IRS tax return from 2 years ago is above a certain amount, you'll pay the standard premium amount and an Income Related Monthly Adjustment Amount, also known as IRMAA. IRMAA is an extra charge added to your premium.
If you owe an IRMAA, Social Security will send you a letter notifying you that your IRMAA will be added to your Medicare Part D cost. Keep in mind that the Part D IRMAA is not billed by or paid to your Part D plan, but rather it is billed by the Centers for Medicare and Medicaid Services (CMS). If you are assessed an IRMAA and do not pay it, you risk disenrollment from your Part D plan.