IRMAA Explained: The Medicare Surcharge Cliffs That Turn $1 of Income into $1,000 of Premiums

Most pre-retirees know Medicare has premiums. Very few know that a single dollar of income in the wrong year can step those premiums up by more than $1,000 annually, and that the year doing the damage is not this year. It is a year you have already closed the books on.

The Two-Year Lookback Is the Trap

IRMAA stands for Income-Related Monthly Adjustment Amount. It is the Social Security Administration's mechanism for charging higher-income Medicare enrollees more for Part B and Part D coverage. The surcharge is not subtle. In 2026, the standard Part B premium is $185.00 per month. At the top IRMAA bracket, that figure climbs to $628.90 per month, per person. For a couple, that is a difference of roughly $10,600 per year, on top of the base premium.

The part that catches people is the lookback. Medicare uses your MAGI from two years prior to set your current-year bracket. Enroll in Medicare in 2026, and SSA is looking at your 2024 tax return. That means a Roth conversion you did in 2024, a business sale that closed in 2024, or a year-end capital gain harvest that pushed you over a threshold is already costing you money today, and there is nothing you can do about it now except understand why the bill is higher.

The 2026 IRMAA Brackets and What Trips Them

For 2026, the IRMAA income thresholds (based on 2024 MAGI) are approximately as follows for individuals filing as single: $106,000, $133,000, $167,000, $200,000, and $500,000. Married filing jointly thresholds are roughly double. Each cliff adds a meaningful surcharge tier. Crossing from just below $106,000 to just above it as a single filer adds approximately $70 per month to your Part B premium alone.

The income events that most reliably push retirees across those cliffs:

• Roth conversions (MAGI impact is dollar-for-dollar)
• Required minimum distributions, which begin at age 73 and can be substantial by age 75 or 76
• A business sale or asset sale generating a large capital gain
• Qualified dividends and taxable interest that accumulate silently in taxable accounts

The planning insight is not to avoid income. It is to know exactly where you stand relative to each cliff before you realize income. A Roth conversion that stops $5,000 below a bracket line is a meaningfully different decision than one that crosses it. This lives squarely in the Soil layer of the Sporos Doctrine, where tax architecture shapes outcomes before a dollar is ever withdrawn.

The SSA-44 and the Appeal You Did Not Know Existed

If your income in the lookback year was elevated due to a one-time event and has since dropped, you are not helpless. The SSA-44 form allows you to appeal your IRMAA determination using a more recent year's income if you experienced a qualifying life-changing event: retirement, divorce, death of a spouse, or loss of income-producing property, among others. A business sale alone does not qualify, but retiring from that business in the same year may. The appeal is worth filing when the facts support it.

What to Do This Week

Pull your 2024 tax return and locate your MAGI. Compare it against the 2026 IRMAA thresholds. If you are within $10,000 of any cliff and have a Roth conversion, RMD, or asset sale on the horizon, that proximity is worth a conversation with your advisor before you act.

If you want a second set of eyes on how your income plan interacts with your Medicare costs, schedule a conversation with our team. We will tell you plainly whether the plan holds or whether there is a cliff worth steering around.

The information provided is for educational purposes only and does not constitute investment, legal, or tax advice. Consult with qualified professionals for guidance specific to your situation.