You retire at 65 and enrol in Medicare. The premium notice arrives and it is considerably higher than the standard amount, because it was calculated from your tax return two years ago — when you were still working and earning a full salary.
That is IRMAA, the income-related monthly adjustment amount, and its two-year lookback catches almost everyone the first time. So does its structure: the brackets are cliffs, so a single dollar over a threshold applies the full surcharge for twelve months.
What changed in 2026
- Bracket thresholds continued adjusting with inflation, which moves the cliffs annually and makes planning against last year's figures unreliable.
- Roth conversion planning got more attention. The interaction between conversions in your early sixties and premiums at 65 became a mainstream planning topic.
- The appeal process stayed under-used. The life-changing event form remains available and remains something many newly-retired people never hear about.
- The two-year lookback did not change. It is structural, not a policy that shifts annually.
How it is calculated
Medicare looks at your modified adjusted gross income from two years prior — the most recent return on file when premiums are set. For premiums in a given year, that means the return from two years earlier.
Compare that figure against a set of brackets. Below the first threshold, you pay the standard premium. Above it, a surcharge is added to both your Part B and Part D premiums, rising through several tiers.
Two structural features do the damage.
The brackets are cliffs. Exceeding a threshold by one dollar moves you into the next tier entirely, for the whole year. There is no phase-in. This is unusual — most tax provisions phase gradually — and it means income near a threshold carries an enormous effective marginal cost.
It applies per person. A married couple both enrolled in Medicare each pay their own surcharge, so the household cost is doubled.
Verify the current-year thresholds before planning around any specific number; they move annually.
The two-year lag, and the appeal
The lookback creates a predictable mismatch: the year you stop working, your premium reflects your last full year of employment income.
There is a remedy, and it is under-used. Social Security accepts an appeal when a life-changing event has reduced your income, and retirement — described as work stoppage or work reduction — is explicitly on the list. So are marriage, divorce, death of a spouse, loss of a pension, and loss of income-producing property.
You file a form, state the event, and provide evidence of your current income. If accepted, they use your actual current income rather than the two-year-old figure.
This is the single most valuable thing to know about IRMAA and many newly-retired people never learn it. If you retired this year and your premium reflects your working income, file the appeal rather than paying a surcharge based on a salary you no longer receive.
Note what does not qualify: a one-off income event like a large capital gain or a Roth conversion is not a life-changing event. Those you plan around rather than appeal.
Planning around the cliffs
Because the brackets are cliffs, income control near a threshold is unusually valuable.
Watch the years that count. Income at 63 sets your premium at 65. If you are planning Roth conversions in your early sixties, those years are exactly the ones that determine your first Medicare premiums. Splitting a large conversion across several years may keep each year under a threshold.
Check before a large realisation. Selling appreciated stock, a property, or a business raises modified AGI. If it pushes you over a threshold, the surcharge is a real additional cost of the transaction that most people never factor in — see capital gains tax explained.
Use qualified charitable distributions. A QCD satisfies a required minimum distribution without adding to AGI, which keeps RMDs from pushing you into a higher bracket. This is one of the cleaner tools available.
Know exactly where you sit. If your projected income is close to a threshold, a small deliberate reduction — deferring income, harvesting a loss, an additional deductible contribution — can be worth far more than its face value.
Common mistakes
- Not appealing after retirement. The most common and most costly oversight.
- Planning against last year's thresholds. They adjust annually.
- Forgetting it applies per person. A couple pays twice.
- Ignoring it when timing a Roth conversion. Conversions at 63 set premiums at 65.
- Missing the Part D surcharge. IRMAA applies to both parts, and people budget only for Part B.
- Assuming it is permanent. It is recalculated annually, so a one-off high year affects one year of premiums.
FAQ
How do I appeal?
File the Social Security form for a life-changing event, documenting the event and your current expected income. It is a short form, and retirement is an accepted reason.
Does a one-off capital gain trigger it?
Yes, two years later, and it is not appealable as a life-changing event. That is precisely why large realisations deserve checking against the thresholds first.
Is it based on taxable income?
No — modified adjusted gross income, which includes tax-exempt interest. Municipal bond interest that is exempt from income tax still counts toward IRMAA, which surprises people holding them for tax efficiency.
What if my income drops but no life-changing event applies?
It resolves itself in two years, since the calculation follows your actual returns. The lag works in both directions.
Where to go next
For enrolment timing and what the parts cover, read the Medicare enrollment guide and Medicare parts explained. For the distributions that drive AGI in retirement, required minimum distributions.
This is general information, not financial advice. Thresholds and surcharge amounts change annually; confirm current figures with Social Security or Medicare.