Medicare IRMAA and the two-year lookback

Many retirees are surprised to discover that Medicare premiums are not the same for everyone. While most people focus on the standard Medicare costs, higher-income retirees may be subject to an additional surcharge known as the Income-Related Monthly Adjustment Amount, or IRMAA. What makes IRMAA particularly frustrating is that it often appears years after the income event that triggered it.

Medicare determines your IRMAA surcharge based on your modified adjusted gross income from two years prior. For example, your 2026 Medicare premiums are generally based on your 2024 tax return. This means a large Roth conversion, business sale, stock sale, or significant capital gain today could result in higher Medicare premiums years down the road. Many retirees don't realize this connection until they receive an unexpected notice from the Social Security Administration.

The good news is that IRMAA is often manageable with proper planning. Before executing a large financial transaction, it's important to understand how the additional income may affect future Medicare costs. Strategic timing of Roth conversions, spreading income across multiple tax years, or coordinating withdrawals from different account types can sometimes help keep income below key IRMAA thresholds.

IRMAA planning becomes especially important during the years surrounding retirement. Many individuals experience a temporary drop in income after leaving the workforce but before claiming Social Security or beginning required minimum distributions. This period can create valuable opportunities for tax planning and Roth conversions while potentially minimizing future Medicare surcharges.

The biggest mistake is simply being unaware that IRMAA exists. Medicare premiums are just one piece of the retirement income puzzle, but they can have a meaningful impact on long-term cash flow. By incorporating Medicare planning into your broader tax and retirement strategy, you can avoid surprises and make more informed decisions about how and when to recognize income throughout retirement.