Medicare's IRMAA surcharge uses tax returns from two years prior, so a stock sale at 64 silently raises premiums at 66. A $90,000 stock gain on top of $70,000 in wages pushes MAGI to ~$160,000, raising Part B premiums from $203 to $406 per month. Splitting a large stock sale across two tax years or harvesting losses can keep MAGI below IRMAA thresholds and avoid a year-long surcharge.
Read More: Learn 7 ways to generate income with a $1,000,000+ portfolio (sponsor) This scenario is common in retirement planning, as a worker approaching retirement holds a concentrated position in company stock, decides at 64 that paying off the mortgage feels better than carrying it into retirement, and sells about $90,000 worth to pay it off. The house is clear, and the plan works, at least for a while. Two years later, the first Medicare bill arrives, and the Part B premium is hundreds of dollars higher than the standard amount, and it stays that way for twelve months.
Nobody at the brokerage, the mortgage servicer, or the Social Security office mentioned that the sale would be doing this to him at 66. The mechanism is Medicare's Income-Related Monthly Adjustment Amount, better known as IRMAA. It is a surcharge added to Part B and Part D premiums for higher-income beneficiaries, and it uses modified adjusted gross income from the tax return filed two years earlier.
A 2024 stock sale shows up on the 2024 return, which determines 2026 premiums. The lag is baked in by statute, which is why the connection is easy to miss. The standard Part B premium in 2026 is $202.90 per month, up $17.90 from $185.00 in 2025.
That is what a single filer pays as long as MAGI stays at or below $109,000. Above that, the surcharges begin, and they move in steps rather than a smooth curve. If you've saved over $1,000,000, this guide is for you.
The last thing you want in retirement is to run out of money, you want your money to generate lasting income while you enjoy your life. Now you can learn the strategies wealthy retirees use to fund their retirement with The Definitive Guide to Retirement Income from Fisher Investments. Download the guide today! (sponsor) For a single filer in 2026, the tiers work like this: MAGI greater than $109,000 and up to $137,000 adds $81.20, bringing the total to $284.10.
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