Projected 2027 IRMAA Brackets for Medicare Part B and D

If you have Medicare Part B or Medicare Part D prescription drug coverage, your monthly costs could look drastically different than the standard rates. High-income retirees are subject to the Income-Related Monthly Adjustment Amount (IRMAA) — a progressive surcharge added directly to your Medicare premiums if your income crosses specific thresholds.

Understanding how the projected 2027 IRMAA brackets are calculated and how the two-year tax lag impacts you is essential to preserving your retirement savings. Failing to plan for these thresholds can trigger an unexpected financial "cliff," where a single dollar of excess income can cost you thousands in annual surcharges.

This year, forecasting the 2027 numbers was more difficult because the Bureau of Labor Statistics (BLS) did not publish official CPI-W data for October 2025, due to the federal government shutdown last year. The official numbers should be released by the Centers for Medicare & Medicaid Services (CMS) by early November of this year.

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All the numbers you will see below are estimates and forecasts. The bracket estimates come from The Finance Buff, and the surcharge amounts are forecasts from the 2025 Medicare Trustees Report.

Missing data impacts the 2027 IRMMA brackets forecast

While it's usually possible to accurately estimate the many IRMAA brackets early, projecting the 2027 IRMAA thresholds carries a unique math problem: the missing Consumer Price Index (CPI) data point from October 2025.

The statutory formula used by the CMS to calculate inflation adjustments relies on a highly specific 12-month window. It evaluates the average Consumer Price Index for All Urban Consumers (CPI-U) from September of the previous year through August of the current year. Because the official October 2025 data point is missing from the record, an estimated "fill-in" value has to be used to run the month averaging formula.

How the Finance Buff compensated for the missing data point: "The Treasury Department used 325.604 as the October CPI to calculate interest on inflation-indexed Treasury bonds. The Social Security Administration won’t necessarily use the same number for IRMAA. I calculated the projected 2027 brackets in two ways: (a) using a straight average of the projected 11 monthly data points, omitting October 2025; and (b) using 325.604 for October 2025. The projected 2027 brackets are largely the same under the two methods due to rounding. I put an asterisk on the number calculated by method (b) where they differ."

I will be sharing one set of numbers, more about that below.

The IRMAA brackets round to the nearest $1,000, so a minor rounding variance caused by that missing data point can shift a projected bracket threshold up or down by a full $1,000. Keep that in mind as you use this information to assess your liability.

Projected 2027 IRMAA income brackets and surcharges

The following tables represent early projections for 2027 based on current inflation mapping and cost-of-living adjustment (COLA) trends. The final, official brackets will be released by the CMS in late autumn, typically by the first week of November.

Due to the missing data I referenced earlier, I am providing more context for the estimated IRMAA brackets in the table below. These income limits I am presenting were prepared by the Finance Buff as if "annualized inflation from May through August 2026 is 3%, approximately a 0.25% increase every month." As of May 2027, seven of the 11 data points needed to compute the IRMAA brackets in 2027 are out. As the remaining data points (CPI-U numbers) are released, the table below will be updated.

Let's get to those numbers. Fortunately, the first four brackets are indexed annually for inflation, while the highest bracket remains legislatively frozen at $500,000 for individuals ($750,000 for joint filers) until 2028.

Projected married filing separately brackets. Taxpayers who are married but choose to file separate returns face highly restrictive IRMAA thresholds:

$112,000 or less: Standard premiums apply ($0 surcharge).

$112,001 to $386,000: $480.90 Part B surcharge + $88.30 Part D surcharge.

$386,000 or more: $524.60 Part B surcharge + $96.40 Part D surcharge.

The two-year tax lag: why your 2025 income matters for 2027

The Social Security Administration (SSA) determines your 2027 IRMAA eligibility using your tax returns from two years prior. Therefore, the income tax return you file for 2025 dictates your 2027 Medicare surcharges. If you are liable for the IRMAA in 2027 and amended your tax return, you should make sure the Social Security Administration (SSA) has the correct information on file.

You cannot report an amended tax return using the standard Life-Changing Event form (SSA-44) unless an actual qualifying event, such as retirement or a divorce, also occurred. Instead, you must contact SSA directly by phone or in person. Be prepared to provide: a signed/stamped copy of your amended tax return (Form 1040-X) and official IRS proof of acceptance, an IRS Form CP21B notice, or a transcript showing the adjustment.

For IRMAA purposes, eligibility is based on your Modified Adjusted Gross Income (MAGI). This is calculated as your Adjusted Gross Income (AGI) plus any tax-exempt interest income, such as interest earned on municipal bonds.

Because of this two-year lookback period, financial decisions made throughout the 2025 calendar year are already locked into your healthcare premium structure for 2027. If your 2025 MAGI exceeds the projected baseline thresholds — estimated to begin at around $112,000 for single filers and $224,000 for married couples filing jointly — you will face an IRMAA surcharge.

How IRMAA shifts the actual cost of Medicare

Many retirees do not realize that the standard Medicare Part B premium does not cover the full cost of the program. In fact, standard premiums are heavily subsidized by the federal government's general fund.

By law, the standard monthly Part B premium is set to cover exactly 25% of the projected actuarial cost of the program for aged beneficiaries. The remaining 75% is funded by taxpayers through general federal revenue.

Where does the 2.9% Medicare tax go? That revenue goes into the Hospital Insurance (HI) Trust Fund to pay for Medicare Part A. Most beneficiaries earn fee-free coverage; you qualify if you or your spouse worked and paid Medicare taxes for at least 10 years (40 quarters).

IRMAA is designed to systematically reduce this government subsidy for higher-income beneficiaries, shifting a much larger percentage of the actual program costs directly onto the enrollee. Depending on which bracket your 2025 income falls into, your IRMAA surcharges will force you to cover a significantly higher share of Medicare's true expenditures:

• Lowest (standard premium): Covers 25% of actual program costs (75% subsidized).
• First IRMAA tier: Covers 35% of actual program costs (65% subsidized).
• Second IRMAA tier: Covers 50% of actual program costs (50% subsidized)
• Third IRMAA tier: Covers 65% of actual program costs (35% subsidized).
• Fourth IRMAA tier: Covers 80% of actual program costs (20% subsidized)
• Fifth IRMAA tier: Covers 85% of actual program costs (15% subsidized)

Beware the IRMAA "cliff"

Unlike progressive federal income tax brackets — where only the money within a specific bracket is taxed at a higher rate — IRMAA operates as a strict cliff. If you cross into a higher tier by a single dollar, your entire surcharge for the year defaults to that higher tier. Crossing from the first tier to the second tier by just $1 in 2025 income means an estimated extra $1,233.60 to $7,452 annually per person in combined Medicare surcharges in 2027. For a married couple filing jointly, that single extra dollar spikes combined health costs to a range of $2,467.20 to $14,904 for the year.

For a detailed look at the types of income that often trigger the IRMAA and actionable income planning strategies to reduce/eliminate your IRMMA liability, read:

7 Ways to Plan Now to Save on Medicare IRMAA Surcharges Later

You have time to plan for 2027 expenses and the 2028 IRMAA

You can't rewrite your 2025 tax history to escape a 2027 IRMAA surcharge, but you can eliminate the sticker shock. Despite the forecasting challenges brought on by the missing October inflation data, matching your locked-in 2025 income against these projected brackets allows you to estimate where your upcoming health costs will land.

Treat these numbers as a financial early-warning system: if your 2025 return puts you on a cliff, updating your 2027 cash-flow projections today ensures you won't be caught flat-footed when the official CMS bills arrive. And, use the lesson to plan your current tax year distributions to protect against the future 2028 cliffs.

Related Content

• How to Appeal the IRMAA for Medicare Parts B and D
• 2027 Social Security COLA Forecast Surges Amid Spike in Inflation
• What You'll Pay for Medicare in 2026
• Medicare Premiums 2026: IRMAA Brackets and Surcharges for Parts B and D
• Your Medicare Costs Are Set to Soar: What to Expect Over the Next Decade