Most investors know that long-term capital gains receive favorable tax treatment compared to ordinary income. However, there is a "hidden" cost to realizing gains in retirement that many overlook: IRMAA (Income-Related Monthly Adjustment Amount). If your income crosses certain thresholds, your Medicare Part B and Part D premiums can skyrocket. Here is what you need to know to avoid a costly surprise in your golden years.
The 2-Year Lookback Rule
Medicare premiums are not based on your current year's income. Instead, they are determined by your tax return from two years prior.
- In 2026, your premiums will be dictated by the income you report on your 2024 tax return.
If you sold a property or rebalanced a large brokerage account in 2024, you might not feel the impact until 2026.
Decoding "Medicare MAGI"
To determine your premium, Social Security looks at your Modified Adjusted Gross Income (MAGI). While "MAGI" is used for many different tax calculations, for Medicare purposes, it has a specific formula:
Medicare MAGI = Adjusted Gross Income (AGI) + Tax-Exempt Interest (e.g., Municipal Bond Interest)
This figure includes almost everything: wages, pensions, Social Security benefits, IRA distributions, and capital gains.
2026 Medicare Part B Premiums (Based on 2024 Income)
Medicare is not a sliding scale; it is a "cliff" system. Going just $1 over a threshold can push you into a significantly higher payment tier.
2024 Income (Single) | 2024 Income (Joint) | 2026 Monthly Premium (Part B) |
$109,000 or less | $218,000 or less | $202.90 (Standard) |
$109,001 – $137,000 | $218,001 – $274,000 | $284.10 |
$137,001 – $171,000 | $274,001 – $342,000 | $405.80 |
$171,001 – $205,000 | $342,001 – $410,000 | $527.50 |
$205,001 – $500,000 | $410,001 – $750,000 | $649.20 |
$500,001+ | $750,001+ | $689.90 |
Note: These surcharges also apply to Medicare Part D (prescription drug) coverage.
Why Strategy Matters
Realizing an extra $10,000 in capital gains might only cost you 15% in federal taxes, which seems efficient. However, if that $10,000 pushes you over an IRMAA bracket, it could trigger thousands of dollars in added Medicare premiums for you (and your spouse) two years later.
When this happens, your "low" 15% tax rate is effectively much higher. This is why it is vital to coordinate where you take your income from—whether it’s a brokerage account, a Traditional IRA, or a tax-free Roth IRA.
We’re Here to Help
Your goal should be to minimize the total cost of your retirement—including income taxes, capital gains taxes, and Medicare surcharges. Navigating these "cliffs" requires a proactive income plan designed years in advance.
If you’re concerned about how your investment strategy might impact your future Medicare costs, let’s talk. Contact us today to build a tailored plan for your retirement income.