IRMAA Brackets 2025: How to Size Your Roth Conversion Without Raising Medicare Premiums

What Is IRMAA?

The Income-Related Monthly Adjustment Amount (IRMAA) is a surcharge that Medicare adds to standard Part B and Part D premiums for beneficiaries whose Modified Adjusted Gross Income (MAGI) exceeds certain thresholds. It is not a penalty for bad behavior — it is simply how Medicare charges higher-income individuals more for the same coverage.

In 2025, the standard Medicare Part B premium is $185.00 per month. At the first IRMAA tier, that jumps by roughly $66/month per person. At the highest tier, the monthly surcharge alone exceeds $400 per person — adding $4,800 or more annually per Medicare beneficiary. For a couple, IRMAA can add $9,600+ per year to healthcare costs.

2025 IRMAA Thresholds (Approximate)

Individual MAGI	Joint MAGI	Part B Monthly Premium
Up to $106,000	Up to $212,000	$185.00 (standard)
$106,001–$133,000	$212,001–$266,000	~$259.00
$133,001–$167,000	$266,001–$334,000	~$370.00
$167,001–$200,000	$334,001–$400,000	~$480.00
$200,001–$500,000	$400,001–$750,000	~$591.00
Over $500,000	Over $750,000	~$628.90

Note: Part D surcharges are additional. Verify current-year thresholds at Medicare.gov.

The Two-Year Look-Back Rule

This is the detail that surprises most retirees. Medicare does not look at your current year's income to set your premium — it uses your tax return from two years prior. A Roth conversion you execute in 2025 will affect your Medicare premiums in 2027. This two-year lag means you must think ahead, not just about this year's taxes, but about the Medicare cost implications two years out.

The practical effect: a large conversion in a single year creates a delayed "tax bomb" in the form of elevated Medicare premiums. Spreading conversions across multiple years to stay below IRMAA thresholds avoids this entirely — or limits you to one tier rather than multiple.

Converting Below IRMAA Thresholds

The most straightforward approach is to calibrate your annual conversion amount to keep MAGI below the first IRMAA threshold ($106,000 single / $212,000 married). For most retirees with modest Social Security and dividend income, there is still meaningful bracket headroom before hitting IRMAA — especially in the early years before RMDs begin.

If crossing one IRMAA tier is unavoidable because of the conversion amount needed, it is sometimes worthwhile to convert to the top of that tier rather than just over it — capturing more tax-free growth while paying only one tier's surcharge, not two.

The Cost-Benefit Calculation

When deciding whether to cross an IRMAA tier, compare the IRMAA cost against the long-term benefit of the conversion. The IRMAA surcharge lasts only one year (two years after the conversion). The tax-free compounding inside the Roth IRA lasts for decades. For retirees with 15+ years of expected investment horizon, even paying one IRMAA tier for one year typically pays off if the converted amount is large enough.

The calculus changes for shorter time horizons or if multiple tiers are triggered. A personalized projection using your account balance, expected return, and health outlook provides a clearer answer than any rule of thumb.

Front-Loading Conversions Before Age 63

Because of the two-year look-back, the Medicare premium you pay at age 65 (when Medicare begins) is based on your income at age 63. For retirees who want to minimize IRMAA during the first years of Medicare, it is advantageous to front-load large conversions before age 63. Large conversions at 60, 61, or 62 affect Medicare premiums at 62, 63, and 64 — years before Medicare has even started. By age 65, the MAGI from those conversions is no longer in the two-year look-back window.

Appealing IRMAA After a Life-Changing Event

If your income has dropped significantly since the tax year Medicare is using to set your IRMAA — due to retirement, loss of a spouse, divorce, or another qualifying event — you can file IRS Form SSA-44 with the Social Security Administration to request a reduction based on your more recent income.

This appeal is not automatic; you must request it and provide documentation. But for retirees who had a large conversion in one year and whose income has since dropped, the SSA-44 can eliminate or reduce IRMAA surcharges based on current circumstances rather than a two-year-old tax return.