How does the Social Security Administration (SSA) determine whether I pay a higher Medicare Part B and Medicare Part D premium?

Your most recent federal income tax returns are used to determine whether you pay an income-related monthly adjustment amount or IRMAA for your Medicare Part D (and Medicare Part B) coverage.  However, this means that your current IRMAA is determined by your income from two years ago.

For example, your 2026 Income Related Monthly Adjustment Amount (IRMAA) is based on the most recent tax return that the IRS provides to the Social Security Administration (SSA) and in general, the IRS will report the financial information provides on your 2024 federal tax returns that were filed in 2025.

But..., it is possible that the IRS will submit a tax return from an earlier year when the most recent return in not available, so you could find that your 2026 IRMAA is being determined using your 2023 federal income tax returns.

Important note: If you find that your IRMAA was determined using an earlier tax return and your income has since changed, you have the right to ask the Social Security Administration to reevaluate your IRMAA using the latest tax return.

More about determining your IRMAA from the Social Security Administration:

To determine if you will pay higher Medicare Part B and Medicare Part D premiums, Social Security uses the most recent Federal tax return that the IRS provides.  If you must pay higher premiums, the Social Security Administration uses a sliding scale to make the adjustments. bases the sliding scale on your modified adjusted gross income (MAGI).

Your MAGI is the total of your adjusted gross income and tax-exempt interest income. If you file your taxes as “married, filing jointly” and your MAGI is greater than $218,000, you need to pay higher premiums for your Part B and Medicare prescription drug coverage.

And some additional IRMAA highlights:

• If you file your taxes using as an individual and your MAGI is greater than $109,000, you also need to pay higher premiums.
  
  
• If you must pay higher premiums, the Social Security Administration will send you a letter with your premium amount(s) and the reason.
  
  
• If you have Medicare Part B and Medicare prescription drug coverage, you will pay higher premiums for both Part B and Part D.
  
  
• If you have only one - Medicare Part B or Medicare Part D prescription drug coverage - you will pay an income-related monthly adjustment amount only on the benefit you have.
  
  
• If you decide to enroll in the other program later in the same year and you already are paying an income-related monthly adjustment amount, the Social Security Administration will apply an adjustment automatically to the other program when you enroll. In this case, the Social Security Administration will not send you another letter explaining how the Social Security Administration made this determination.
  
  
• If your income is not greater than the limits described above, this law does not apply to you.
  
  
• The amount of IRMAA you pay can change each year depending on your income.
  
  
• If you have to pay a higher amount for your Part B premium and you disagree, you can appeal your IRMAA.
  

Example: 2026 Medicare Part D IRMAA information
2026 IRMAA: Slight increase in Medicare Part D IRMAA payments for some.  ( on this site)

For more information about IRMAA and current IRMAA limits see our Latest Medicare News
on this site