IRMAA is a Medicare premium adjustment driven by tax-return income
Income-Related Monthly Adjustment Amounts, or IRMAA, can increase Medicare Part B and Part D costs for beneficiaries whose modified adjusted gross income exceeds the applicable thresholds. Social Security uses federal tax-return information to make the determination.
A taxable inherited traditional IRA distribution can increase adjusted gross income and therefore can raise the MAGI used for IRMAA. The inherited-IRA rule itself does not change; Medicare is a second system that can be affected by the same distribution.
For 2026 premiums, Social Security generally looks to tax year 2024
SSA’s 2026 Medicare premium guidance says it generally uses the most recent federal tax return supplied by the IRS, usually the return filed in 2025 for tax year 2024. If the 2024 return is unavailable, SSA can use older information and later update the determination.
This creates the familiar two-year relationship: a large taxable distribution in one tax year can affect Medicare premiums in a later year rather than immediately.
2026 provides a concrete threshold example
For 2026, SSA lists the first IRMAA threshold above modified adjusted gross income of $109,000 for an individual filer and above $218,000 for a married couple filing jointly. The standard Part B premium is $202.90 per month in 2026, with additional Part B and Part D amounts at higher MAGI levels.
Those figures are useful only as a dated example. A beneficiary making a ten-year inherited-IRA plan should replace them with the official thresholds for the premium year being modeled.
IRMAA MAGI is not simply the taxable amount of the IRA withdrawal
Form SSA-44 instructions describe MAGI for this purpose as adjusted gross income from Form 1040 plus tax-exempt interest income. A taxable inherited IRA distribution can raise AGI, but it is only one input. Wages, pensions, interest, dividends, capital gains, and other items can also affect the total.
That is why there is no reliable permanent “safe inherited IRA withdrawal” amount without considering the rest of the return.
Required RMDs come first
If an inherited IRA RMD is legally required, concern about Medicare premiums does not authorize the beneficiary to skip it. The RMD is the compliance floor. IRMAA analysis is relevant to additional voluntary withdrawals and to how aggressively the beneficiary reduces the remaining account before the final year-10 deadline.
Keeping those two numbers separate prevents a Medicare-cost projection from being mistaken for a legal distribution limit.
Example: a one-time distribution can affect a later premium year
Assume a Medicare beneficiary takes a large taxable inherited traditional IRA distribution in 2026. The distribution belongs on the 2026 tax return and can increase 2026 MAGI. Under the usual two-year lookback pattern, that income can be relevant to a 2028 IRMAA determination, subject to the SSA rules and data available for that premium year.
The example is about timing. It does not assume the beneficiary will cross a threshold, because that depends on filing status, total MAGI, and the threshold schedule in effect for 2028.
SSA-44 is for specified life-changing events, not simply for “one-time income”
SSA allows a beneficiary to request a lower IRMAA determination when a qualifying life-changing event reduces household income. The current SSA-44 lists events such as marriage, divorce or annulment, death of a spouse, work stoppage, work reduction, loss of income-producing property, loss of pension income, and certain employer settlement payments.
An inherited IRA withdrawal by itself is not one of the listed life-changing events. A beneficiary should not assume that a large one-time distribution can automatically be removed from the IRMAA calculation simply because it will not recur.
Amended or corrected tax information uses a different SSA process
SSA guidance also permits a new determination in situations involving an amended tax return, corrected IRS information, or use of a more recent tax year when older information was used. Those paths are distinct from a life-changing-event request.
A beneficiary who believes an IRMAA notice is based on the wrong tax information should review the notice and the current SSA instructions rather than trying to force the situation into Form SSA-44.
A useful two-column planning worksheet
| Tax-year side | Medicare-premium side |
|---|---|
| Taxable inherited IRA distribution | Potential later IRMAA premium year |
| Other AGI items | SSA MAGI threshold for that premium year |
| Tax-exempt interest | Part B and Part D adjustment amounts |
| Required RMD vs optional withdrawal | Whether any qualifying SSA reassessment event actually applies |
This makes the timing lag visible and discourages the mistake of comparing a current-year withdrawal only with a current-year Medicare bill.
Use current SSA and Medicare tables every year
IRMAA thresholds and premium amounts change. For a beneficiary with several years left before the inherited IRA must be emptied, the most reliable process is to update the Medicare side annually using SSA or Medicare.gov and to keep the federal RMD deadline in a separate compliance schedule.