Skip to navigationSkip to main contentSkip to right columnADVERTISEMENTDrew WoodSun, June 28, 2026 at 5:20 PM GMT+2 6 min readQuick ReadMedicare's two-year lookback means your 2024 Roth conversions, RMDs, or property sales can unexpectedly spike your 2026 Part B and Part D bills.IRMAA brackets are cliff-edged, meaning one dollar over a joint threshold locks a couple into up to $480 more monthly for the entire year.Voluntary income events like Roth conversions and home sales don't qualify for SSA-44 appeals. Only qualifying life events that reduced income do.Are you ahead, or behind on retirement? SmartAsset's free tool can match you with a financial advisor in minutes to help you answer that today. Each advisor has been carefully vetted, and must act in your best interests. Don't waste another minute; learn more here.A 67-year-old couple opened their January 2026 Social Security deposit and found nearly $500 less than they expected. The culprit was a Roth conversion they ran in 2024 to lock in lower brackets before they thought rates might rise. The conversion did exactly what they planned for taxes. It also pushed their modified adjusted gross income from two years prior into a Medicare income-related surcharge bracket they had never heard of.sergey kolesnikov / Shutterstock.comThis article is for the small slice of Medicare beneficiaries who will trip this wire. CMS says income-related Part B adjustments affect about 8% of people with Medicare Part B. If your household MAGI was comfortably under the first threshold in 2024, IRMAA may not affect your 2026 Medicare bill. If 2024 was the year you sold a rental, took a large required minimum distribution, ran a Roth conversion, or collected a severance payment, keep reading.Medicare generally bases your 2026 Part B and Part D surcharges on the MAGI reported on your 2024 federal tax return, and Social Security makes the IRMAA determination using IRS data. The determination letter identifies the tax year used, the income amount, and the surcharge. MAGI for IRMAA is your adjusted gross income from Form 1040, line 11, plus tax-exempt interest from line 2a. Municipal bond income that feels tax-free still counts here.Are you ahead, or behind on retirement?