Understanding the IRMAA Two-Year Look-Back Rule
Understanding the IRMAA Two-Year Look-Back Rule and how income from two years ago can increase Medicare Part B and Part D premiums for retirees.
Imagine retiring at 63 after decades as a senior executive, spending two years managing a careful transition, and then receiving your first Medicare bill at 65 — for $649.20 per month in Part B premiums alone, per person. Not because you are wealthy in retirement, but because of what you earned at 62. That is the IRMAA two-year look-back rule at work, and it catches more pre-retirees off guard than almost any other Medicare provision. Understanding how the look-back operates and what you can do when the timing works against you — is one of the most valuable things you can do in the years before Medicare begins. See our Complete IRMAA Planning Guide for pre-retirees.
What Is the IRMAA Two-Year Look-Back Rule?
The IRMAA two-year look-back rule means that the income used to determine your Medicare Part B and Part D surcharges is from your tax return filed two years before the current benefit year. For 2026 premiums, Social Security uses your 2024 MAGI. For 2027 premiums, they will use your 2025 MAGI. There is no exception based on your current income level — unless a qualifying life-changing event has occurred.
Why the IRS and Social Security Use Old Tax Data
The two-year lag is not arbitrary — it is a data-availability constraint. When Medicare premiums are set for a given year, the most recent complete federal tax returns are typically those filed the previous April, covering income from two years prior. Social Security cannot use "this year's income" because that return has not been filed yet.
In practice, the Social Security Administration uses data shared by the Internal Revenue Service under a formal data-sharing agreement. According to the Social Security Administration, when SSA does not have your most recent tax data available, they may use the return from three years prior — making the look-back problem potentially even worse in some edge cases.
The Year-by-Year Mechanics: A Clear Example
To make the look-back concrete, here is how it works for someone who retires at 65 in 2026:
Year Activity Income Used for IRMAA?
2024 Final full year of work — MAGI: $390,000 Sets 2026 Medicare premiums
2025 Retired in March — partial year income of $185,000 Sets 2027 Medicare premiums
2026 Full year in retirement — Social Security + IRA withdrawals: $120,000 Sets 2028 Medicare premiums
2027 Full retirement — MAGI: $118,000 Sets 2029 Medicare premiums
In this scenario, the person's first year on Medicare (2026) has premiums based on their 2024 working income of $390,000. At that level, they sit in Tier 4, paying $649.20 per month per person for Part B — plus $83.30 for Part D. For a couple, that is $1,465.00 per month in Medicare Part B premiums, versus $405.80 for a couple who entered retirement from a lower income. By 2028 or 2029, their premiums will normalize to reflect their actual retirement income. But those first two years can easily cost $10,000–$15,000 in excess premiums that have no planning remedy after the fact.
The High-Risk Situations for Look-Back Penalties
Retiring at or Near Age 65
The classic look-back trap: your last year of W-2 income is exactly the year that sets your first Medicare premiums. If your employer pays you through December 31 of the year you turn 65, that full working-year income is the baseline. Nothing can undo this retroactively. The remedy — if there is one — is a mid-year retirement that keeps your final year's MAGI meaningfully lower.
The Business Sale Problem
Selling a business or investment property often generates a one-time capital gain that can be five to ten times your normal annual income. A business owner who sells for $2 million in 2024 with a $1.5 million gain could see MAGI well above $1 million that year — triggering the maximum IRMAA tier for both 2026 and, if the business generated deferred income, potentially beyond. The only relief available is an appeal if circumstances change again. [See our guide to IRMAA appeals using Form SSA-44].
Roth Conversions Without Bracket Awareness
Roth conversions are one of the most powerful tools for retirement tax planning. But they add directly to MAGI in the year of conversion. A couple doing a $200,000 Roth conversion in 2024 — without accounting for the IRMAA impact two years later — could inadvertently push themselves from Tier 2 into Tier 3 for 2026, paying an extra $2,928 per year in premiums per person. This is not a reason to avoid Roth conversions; it is a reason to calibrate them precisely to IRMAA thresholds. [See the full 2026 IRMAA brackets here].
The RMD Stack
Required Minimum Distributions begin at age 73. The income they generate is permanent — once you reach RMD age, you cannot stop distributions. For retirees with large traditional IRA balances (say, $1.5 million or more), first-year RMDs can be $60,000–$80,000. That income stacks on top of Social Security, pensions, and any interest or dividends. For retirees who did not do Roth conversions in their 60s, RMDs can push them into an IRMAA tier and keep them there indefinitely.
What the Look-Back Does Not Cover: When It Works In Your Favor
The look-back is not always punishing. For someone who had one particularly high-income year — a severance payment, a lawsuit settlement, a one-time bonus — the look-back means that elevated income affects premiums for just two years. By year three, if your ongoing income is lower, your premiums normalize. You do not need to take action in that case; time is the remedy.
Similarly, if your 2024 income was exceptionally low — perhaps you took a sabbatical, had a medical issue that reduced income, or made large deductible contributions — your 2026 Medicare premiums could be unusually low. The look-back can occasionally be a windfall.
When Can You Override the Look-Back? Life-Changing Events
The one formal mechanism for overriding the two-year look-back is the Social Security Administration's Form SSA-44, which allows you to request that SSA use a more recent year's income if a qualifying life-changing event has reduced your income. Qualifying events include:
1. Retirement or reduction in work hours — the most common trigger for pre-retirees
2. Death of a spouse
3. Divorce or annulment
4. Loss of income-producing property (for example, a rental property damaged by a disaster)
5. Loss of pension income (due to a plan termination)
6. Employer settlement payment related to employer bankruptcy
Importantly, investment losses — even severe ones — do not qualify as a life-changing event for IRMAA purposes. If your portfolio dropped 30% but your MAGI did not change meaningfully, that does not trigger SSA-44 relief. [Read our full guide to the IRMAA appeal process].
How the Appeal Works in Practice
If you retired in March 2025 and your 2025 income was substantially lower than your 2024 income, you can file Form SSA-44 to request that SSA use your 2025 income (or an estimate of your 2026 income) for your 2026 IRMAA determination. You will need to provide your most recent tax return and documentation of the qualifying event. SSA will make a new determination and adjust your premiums accordingly, often retroactively if premiums were already collected.
Proactive Strategies: Planning Around the Look-Back
Given that the look-back is a fixed feature of Medicare, here is how sophisticated pre-retirees plan around it:
1. Engineer Your Retirement Date to Minimize Final-Year Income
If you have flexibility about when to retire, retiring partway through a calendar year (January through June) rather than at year-end meaningfully reduces your final year's MAGI. A partial-year salary of $150,000 creates less IRMAA pressure than a full-year salary of $310,000.
2. Calibrate Roth Conversions to Stay Below Bracket Cliffs
In the years between retirement and the start of RMDs (your mid-60s to age 73), your income often drops to its lowest point. These are the ideal years for Roth conversions — but the conversion amount should be calculated against the IRMAA thresholds for the year the conversion will affect premiums, which is two years out.
3. Use QCDs to Reduce RMD Impact
Once you reach 70½, Qualified Charitable Distributions from your IRA can satisfy part or all of your RMD without adding to your MAGI. A QCD reduces the income that flows into the IRMAA calculation. In 2026, the QCD limit is $108,000 per person.
4. Review Your Look-Back Window Every Year
The best approach is to run the IRMAA calculation every year — two years in advance — as part of your overall income planning. If you know your 2025 MAGI is going to be $272,000 and the Tier 2 threshold for 2027 is likely to be around $280,000 (accounting for inflation adjustments), you may have room for an additional Roth conversion this year without crossing a bracket line.
Frequently Asked Questions About the IRMAA Look-Back Period
Which year's income sets my 2026 Medicare premiums?
Your 2024 MAGI, as reported on your 2024 federal income tax return and shared by the IRS with the Social Security Administration, determines your 2026 IRMAA status and premiums.
What if I did not file a 2024 tax return?
If Social Security cannot locate your 2024 return, they will use the most recent return available — potentially your 2023 return. If that return also shows elevated income, your premiums could reflect a higher bracket. If no return is on file, SSA may use their own determination, which you can challenge.
I retired in 2025. Will my 2026 premiums still be based on my 2024 working income?
Yes, initially. However, if you retired in 2025 and your income dropped significantly, you can file Form SSA-44 to request that SSA use your 2025 income or a 2026 income estimate instead. You will need to provide evidence of the retirement and an estimate of your reduced income.
Does the look-back apply to Medicare Advantage enrollees?
Yes. The IRMAA look-back applies to all Medicare Part B enrollees regardless of whether they are in Original Medicare or a Medicare Advantage plan. It also applies to Part D enrollees regardless of drug plan type.
What happens if my 2024 return was amended after IRMAA was already determined?
If you file an amended return that reduces your MAGI below an IRMAA threshold, you can notify SSA and provide the amended return. SSA can recalculate your IRMAA based on the corrected income figures.
Are Social Security benefits included in MAGI for IRMAA?
The taxable portion of your Social Security benefits is included in your AGI, and AGI is part of MAGI. However, Social Security benefits that are not taxable (below the thresholds under IRS provisional income rules) are not included.
The Right Time to Plan for the Look-Back Is Before It Is Too Late
The two-year look-back is both the biggest planning challenge and the biggest planning opportunity in Medicare. Two years is actually enough lead time to take meaningful action — if you know what to do. If you are 62 to 71 and have not yet thought systematically about which years of income are flowing into which years of Medicare premiums, this is worth a focused conversation. I offer a complimentary 20-minute Retirement Fit Call to walk through your income picture and identify where the look-back might hurt you — and what can still be done. Schedule your Retirement Fit Call
Sentient Financial, LLC is a state-registered investment adviser in California. This information is for educational purposes only and does not constitute investment, tax, or legal advice. Nothing here should be taken as a recommendation to buy or sell securities or to implement a specific strategy. Past performance does not guarantee future results. IRMAA figures are for the 2026 benefit year as published by the Centers for Medicare & Medicaid Services.
