IRMAA Basics
Understanding IRMAA's Impact on Medicare Part B and D Premiums
Verified against SSA POMS as of August 17, 2026
The short answer
Income-Related Monthly Adjustment Amount (IRMAA) affects Medicare Part B and D premiums by adding a surcharge based on income levels. IRMAA applies if your modified adjusted gross income (MAGI) exceeds certain thresholds. Part B premiums consist of the standard premium plus IRMAA, while Part D premiums include the plan premium plus IRMAA. MAGI is typically assessed using the filed tax return from 2 years prior to the current premium year available from the IRS. If the P-2yr return is not available, the IRS will use the return from 3 years prior to the premium year.
IRMAA and Medicare Part B Premiums
Beneficiaries with a MAGI above specific thresholds must pay an IRMAA surcharge in addition to the standard Medicare Part B premium. The IRMAA is determined based on the beneficiary's tax return information provided by the IRS, specifically using the MAGI from the beneficiary's Form 1040 from two years prior. For example, if a beneficiary is applying for 2026 Medicare benefits, the SSA will request the 2024 IRS tax information for that beneficiary. This surcharge is evaluated each year for every Medicare beneficiary. If P-2 year tax information is not available, the IRS will send information to the SSA based upon the P-3 year tax information. If the P-2 and P-3 returns are unavailable, the beneficiary may be charged the maximum IRMAA surcharge unless the beneficiary’s income was so low as to not require a filed tax return.
HI 01194.005 View source ›IRMAA and Medicare Part D Premiums
The IRMAA applied to Medicare Part D is an additional charge on top of the Part D plan premium. The Social Security Administration determines this adjusted amount using the beneficiary's MAGI, similar to Part B. The actual dollar amount of the Part D IRMAA surcharge is derived from the base beneficiary premium, which serves as the starting point for calculating IRMAA D surcharges. The base beneficiary premium is calculated using the national average monthly bid amount (NAMBA). The IRMAA-D is withheld from the beneficiary's Social Security benefits or might result in a separate bill if benefits do not cover the surcharge.
HBK 2505 View source ›Determining IRMAA Based on Income
IRMAA is applied if the beneficiary's income, taking into account tax filing status and MAGI, surpasses defined income thresholds. MAGI is calculated by adding line 11a, which is used for adjusted gross income, and line 2a, which is used for tax-exempt interest, from the IRS form 1040. IRMAA impacts both Part B and D premiums separately, and the amounts due are updated annually in accordance with income levels reported to the IRS.
HI 01101.001 View source ›Frequently asked
How is Medicare Part B IRMAA calculated?
Medicare Part B IRMAA is calculated based on your modified adjusted gross income (MAGI) using data from the IRS form 1040 from two years prior to the Medicare premium year. This means if you are paying premiums in 2023, your MAGI from the 2021 tax year is used. If the tax return from two years prior is unavailable, the IRS will provide the Social Security Administration (SSA) with beneficiary tax information from the form 1040 from three years prior to the premium year. The IRMAA is an additional charge on top of the standard Part B premium.
Do I have to pay IRMAA if I enroll in Medicare Part D?
Yes, if your income is above the specified IRMAA thresholds, you will pay an IRMAA surcharge in addition to your regular Medicare Part D plan premium.
What income is used to determine IRMAA?
The income used to determine IRMAA is your modified adjusted gross income (MAGI), which includes adjusted gross income and any tax-exempt interest income. This calculation is based on the tax return filed with the IRS from two years prior to the premium year in question.
Can IRMAA for Part D be deducted from Social Security benefits?
Yes, the IRMAA for Medicare Part D can be deducted from your Social Security benefits. If your benefits do not cover it, you'll receive a separate bill.
What happens if my income decreases after IRMAA is applied?
If your income decreases significantly due to a life-changing event, you may request a new IRMAA determination using more recent income information by filing Form SSA-44. This form is used by the beneficiary to alert the Social Security Administration (SSA) of the life-changing event that has affected their income.