IRMAA, or Income-Related Monthly Adjustment Amount, is an additional surcharge that may apply to Medicare Part B and Part D premiums based on your income. In simple terms, the more income you report, the higher your Medicare premiums may be.
IRMAA is determined using your modified adjusted gross income from a prior tax year, which means there is often a lag between income events and when the adjustment shows up in your Medicare costs. This can catch retirees off guard, especially after large one-time income events such as Roth conversions, investment gains, business sales, or required minimum distributions.
Understanding how different income sources impact IRMAA is an important part of tax and retirement planning. Even a temporary increase in income can move you into a higher IRMAA tier, increasing monthly healthcare costs for an entire year.
The key to managing IRMAA is proactive planning. Strategies such as spreading income over multiple years, coordinating Roth conversions carefully, and managing capital gains can help reduce unexpected premium increases. In some cases, appealing IRMAA may also be possible if your income has changed due to a qualifying life event.
Because IRMAA is based on prior tax returns and can have a meaningful impact on retirement expenses, it is important to coordinate tax decisions with your overall Medicare planning strategy.