The 2027 Medicare IRMAA brackets: the formula is fixed, the dollars are not out yet

In short: an income-tested surcharge added on top of the standard Part B and Part D premiums.

IRMAA stands for Income Related Monthly Adjustment Amount. If your modified adjusted gross income, from a tax return filed two years before the plan year, is above a set threshold, you pay the standard Part B premium plus a surcharge, and a separate Part D surcharge on top of whatever your plan charges. For 2027, that means your 2025 tax return is what counts, and it has already been filed. There is nothing left to do about your 2027 IRMAA status; it is locked to income you cannot change now.

In short: the thresholds are set by law, not by CMS discretion, and the last input publishes September 11, 2026.

Section 1839(i)(5) of the Social Security Act, at 42 U.S.C. 1395r(i)(5), sets the method: each year's threshold equals the prior year's threshold adjusted by the percentage increase in the CPI-U for the twelve month period ending with August of the preceding year, versus the same period a year earlier. There is no discretion in this. Once the August CPI-U reading publishes, the thresholds are arithmetic, not policy.

The Bureau of Labor Statistics has the August 2026 CPI-U release scheduled for September 11, 2026. That is the date the 2027 IRMAA income thresholds become calculable, even though CMS will not formally publish them until its fall fact sheet weeks or months later. Note one wrinkle from the prior year's cycle: the October 2025 CPI-U reading was delayed by a government shutdown, a reminder that the schedule can slip.

Harry Sit, who writes as The Finance Buff and has tracked this calculation closely for years, put the mechanical nature of it plainly in his own IRMAA projections: the thresholds "will be officially announced by IRS/SSA later, but we can already calculate them" once the requisite CPI data is in. That is the premise of this page.

In short: tier 1 is projected at about $112,000 single, $224,000 married filing jointly, roughly 2.75% above 2026.

These are projections built on partial year CPI-U data, not the final calculation. We will update this table the moment the August reading publishes on September 11, 2026, and again when CMS confirms the figures in its own fact sheet.

In short: knowing the income line you cross is not the same as knowing what crossing it costs.

This is the distinction most coverage collapses, and it is worth being precise about. The income thresholds above are a pure CPI calculation, fixed by statute, and effectively knowable now. The dollar surcharge at each tier is a percentage of the standard Part B premium, and the standard Part B premium for 2027 is still a projection, not an announced figure. See the 2027 Part B premium page for that separate, unsettled number.

Practically: we can tell you today, with reasonable confidence, which income line matters for you in 2027. We cannot tell you the exact monthly surcharge until CMS publishes the Part B premium, typically in the fall.

In short: some tier boundaries move on a fraction of a percentage point of inflation, which is why the projected table can still shift.

Because thresholds round to the nearest thousand dollars, a small change in the underlying CPI-U reading can be the difference between one rounded threshold and the next. On at least one recent tier, the gap between rounding up and rounding down was as small as roughly 0.04 percentage points of the underlying index movement, meaning a single month's data revision could, in principle, move the published number by a full thousand dollars at that boundary.

This is a reason to treat the table above as directionally right rather than penny-precise until the August reading is in.

In short: modified adjusted gross income, which is broader than what most people think of as taxable income.

IRMAA uses modified adjusted gross income, which is adjusted gross income plus tax-exempt interest. It includes things that surprise people:

• Tax-exempt municipal bond interest, even though it is not taxed.
• Capital gains, including a one-time large gain from selling a home or investment property.
• Required minimum distributions from traditional IRAs and 401(k)s.
• Roth conversions, which move money to a tax-free account but count as income in the year converted.
• Most pension and Social Security income, per the standard AGI calculation.

In short: Form SSA-44 lets Social Security use a more recent, lower income figure if you had a qualifying life event.

IRMAA normally looks back two years, which is why your 2027 status depends on your already-filed 2025 return. But Social Security allows an appeal using Form SSA-44 if you experienced one of a defined list of qualifying life-changing events since that return was filed. The eight events SSA recognizes are:

1. Marriage
2. Divorce or annulment
3. Death of a spouse
4. Work stoppage, meaning you or your spouse retired or reduced hours
5. Work reduction
6. Loss of income-producing property beyond your control
7. Loss of pension income, such as a plan terminating
8. Employer settlement payment, for example from a company closure or bankruptcy

A general market downturn, an ordinary investment loss, or simply having a lower income this year without one of those specific triggers does not qualify. If one of these events applies to you, SSA-44 lets you use a more current income estimate instead of the two-year-old figure.

1. If a qualifying life event happened since your 2025 return, gather documentation for Form SSA-44 now rather than in November.
2. If you are planning a large 2026 taxable event, a Roth conversion or an asset sale, know that it affects your 2028 IRMAA status, not 2027, since the lookback is two years.
3. Do not act on the projected dollar thresholds above as final. Wait for the September 11 CPI-U release, then check back here.
4. Everything else about 2027, gathered in one place: the 2027 Medicare numbers page.

• Aug 13, 2026Page created. Tier 1 threshold projection recorded pending the September 11, 2026 CPI-U release.

• 42 U.S.C. 1395r(i)(5), the IRMAA threshold indexing formula
• Bureau of Labor Statistics, Consumer Price Index release schedule
• CMS, 2026 Medicare Parts A & B Premiums and Deductibles fact sheet, November 14, 2025
• Social Security Administration, Form SSA-44, Medicare Income-Related Monthly Adjustment Amount Life-Changing Event
• 2026 Medicare Trustees Report, Table V.E2, transmitted June 9, 2026