What Is the Income-Related Monthly Adjustment Amount (IRMAA)?

The Income-Related Monthly Adjustment Amount (IRMAA) is an additional charge applied to Medicare Part B and Part D premiums for higher-income beneficiaries. It is determined based on a person’s modified adjusted gross income (MAGI) from two years prior, as reported on their tax return. The Social Security Administration (SSA) and the Centers for Medicare & Medicaid Services (CMS) oversee IRMAA calculations and adjustments.

How IRMAA Works

Medicare beneficiaries typically pay a standard monthly premium for Part B (which covers outpatient services) and, if enrolled, an additional premium for Part D prescription drug coverage. However, individuals with higher income levels must pay an extra surcharge, known as IRMAA, on top of their standard premiums. This adjustment is meant to ensure that those with greater financial resources contribute more to the Medicare system.

IRMAA is calculated annually and is based on a beneficiary’s tax return from two years prior. For example, an individual’s 2025 IRMAA determination is based on their 2023 tax return. The IRS provides income data to the SSA, which then determines whether a beneficiary is subject to IRMAA and notifies them accordingly.

Income Brackets and Thresholds

IRMAA applies only to those whose MAGI exceeds a specific threshold. The income brackets are adjusted annually for inflation, and different tiers determine the level of surcharge applied. Generally, the more a beneficiary earns, the higher their IRMAA surcharge.

MAGI for IRMAA purposes includes adjusted gross income (AGI) plus certain excluded income items such as tax-exempt interest. Common sources of MAGI include wages, Social Security benefits, pensions, capital gains, rental income, and withdrawals from retirement accounts like IRAs and 401(k)s.

Notification and Appeal Process

When the SSA determines that a beneficiary owes IRMAA, they issue a formal notice outlining the additional charges. If a beneficiary disagrees with the assessment — perhaps due to a significant life event that lowered their income — they have the right to appeal.

Life-changing events that may justify an appeal include:

• Retirement or reduction in work hours
• Marriage, divorce, or the death of a spouse
• Loss of income from income-producing property
• Loss of pension or employer-provided income

To request an adjustment, beneficiaries must complete Form SSA-44 (Medicare Income-Related Monthly Adjustment Amount - Life-Changing Event) and provide supporting documentation. The SSA reviews the request and may adjust IRMAA based on the new financial situation.

Impact on Medicare Costs

IRMAA can significantly increase out-of-pocket costs for higher-income Medicare beneficiaries. While the standard Medicare Part B premium is the same for most enrollees, those subject to IRMAA may pay hundreds more per month. Similarly, Part D prescription drug coverage becomes more expensive as higher-income beneficiaries must pay additional amounts on top of their plan premiums.

For those on a fixed income or planning for retirement, IRMAA can be an unexpected expense. Careful tax and financial planning can help individuals manage their MAGI to avoid unnecessary IRMAA surcharges. Strategies such as Roth IRA conversions, tax-loss harvesting, and controlling retirement account withdrawals may help keep income below IRMAA thresholds.

The Bottom Line

IRMAA is an additional cost imposed on higher-income Medicare beneficiaries to ensure that wealthier individuals contribute more to the Medicare system. It is based on income reported two years prior and applies to both Medicare Part B and Part D premiums. While it increases healthcare costs for those who qualify, proactive tax planning can help mitigate its impact. Beneficiaries who experience a reduction in income due to life events have the right to appeal, potentially lowering or eliminating their IRMAA charges.