IRMAA Basics
Understanding the IRMAA Cliff and Its Financial Impact
Verified against SSA POMS as of August 28, 2026
The short answer
IRMAA Cliff Effect: The Income-Related Monthly Adjustment Amount (IRMAA) applies an extra premium to Medicare Parts B and D if your income exceeds certain thresholds. A minor increase in income can result in crossing a threshold, causing substantial premium increases.
What is the IRMAA Cliff Effect?
The IRMAA cliff effect refers to the sudden increase in Medicare premiums for Part B and Part D when a beneficiary's income exceeds specific thresholds. Even a small increase in income, such as $1 over the limit, can significantly increase premiums due to crossing these income thresholds.
MCR:basics/forms-publications-mailings/mailings/costs-and-coverage/initial-income-related-monthly-adjustment-amount-notice View source ›How IRMAA Thresholds Impact Medicare Costs
Medicare uses a sliding scale based on your Modified Adjusted Gross Income (MAGI) to determine whether the IRMAA should be added to your monthly premiums for Part B and Part D. The additional amounts are progressively higher for those with greater incomes.
MCR:node/26306 View source ›Consequences of Crossed Thresholds
Exceeding the IRMAA income threshold by even a small amount can move you to a higher premium tier, resulting in a considerable increase in your monthly Medicare costs. The effect is sharply felt because of the cliff-like structure of the pricing. For example, if a single filer is a Medicare beneficiary in 2026 and has a modified adjusted gross income (MAGI) in 2024 of $137,000, his Part B premium plus IRMAA surcharge would be $284.10 per month. If his MAGI was $1 more, his Part B premium plus IRMAA would be $405.80 per month. That's an additional $1,460 of IRMAA surcharges over the course of a year. The same MAGI thresholds would also apply to his Part D drug plan. That same $1 increase in his MAGI would mean an additional $276 annually for his Part D IRMAA.
CMS:medicare/enrollment-renewal/original-part-a-b View source ›Frequently asked
How does the IRMAA cliff work?
The IRMAA cliff occurs when a $1 increase in income pushes you over a threshold, raising your Medicare premiums significantly.
Can $1 really cause a big increase in my Medicare premiums?
Yes, if that $1 moves you over an IRMAA threshold, your premiums for Medicare Part B and D can increase substantially.
How can I avoid the IRMAA cliff?
Careful financial planning to keep your Modified Adjusted Gross Income below the IRMAA threshold can help avoid sudden premium increases. The decisions you make concerning your income in a given year will impact your potential IRMAA surcharges two years later. While it is impossible to predict exactly where the IRMAA brackets will land in the future, it is likely that the dollar amounts for each threshold will not decrease. Working with your tax advisor and financial professional can help you plan accordingly.
What income affects IRMAA calculations?
Medicare calculates IRMAA using your Modified Adjusted Gross Income (MAGI) from your federal tax return. MAGI is determined by adding your adjusted gross income (AGI) to any tax-exempt interest. On the current IRS 1040 form, this is the sum of line 2a and line 11a.