Glossary
IRMAA
An income-based surcharge added to your Medicare Part B and Part D premiums if your income exceeds CMS thresholds.
Also known as: Income-Related Monthly Adjustment Amount, Medicare income surcharge
What is it?
IRMAA (Income-Related Monthly Adjustment Amount) is an extra amount higher-income beneficiaries pay on top of the standard Medicare Part B and Part D premiums. CMS calculates it based on your modified adjusted gross income (MAGI) from two years prior, as reported by the IRS.
Why does it matter?
Retired senior officers, dual-income households, and retirees with large pension or investment income often trigger IRMAA. It can add hundreds of dollars per month to the Part B premium.
When you'll encounter it
You'll receive an IRMAA determination letter from SSA each fall for the following year. The income thresholds and surcharge amounts update annually.
Impact on Medicare
Increases your Part B (and Part D, if you have one) premium. The base service coverage is identical.
Impact on TRICARE For Life
IRMAA doesn't change your TFL coverage. TFL has no income test and no IRMAA-style surcharge. But IRMAA does increase the Part B premium you must keep paying to retain TFL.
Impact on Medicare Advantage
Joining MA doesn't avoid IRMAA — you still pay the full Part B premium plus IRMAA. However, a Part B giveback can offset part of that cost.
Common misconceptions
- "IRMAA is permanent." — It's recalculated every year. If your income drops (retirement, life event), file SSA Form SSA-44 to appeal.
Related glossary terms
Related questions
Official sources
Last reviewed January 2026 against the 2026 Medicare & You and TRICARE For Life handbooks.