RMDs impact on tax brackets and Medicare premiums

Required minimum distributions are one of the most overlooked tax burdens in retirement. Once you reach age 73, the IRS mandates annual withdrawals from your Traditional 401k and other pre-tax accounts, and every dollar counts as ordinary income. That mandatory income can push retirees into higher federal tax brackets, trigger the taxation of Social Security benefits, and raise Medicare premiums by thousands of dollars each year through a mechanism called IRMAA.

Understanding how required minimum distributions fit into your overall tax picture is one of the most consequential planning tasks in retirement. Without a clear strategy, a single large distribution can trigger a cascade of unintended tax costs that reduce your after-tax income far beyond the RMD itself. The encouraging reality is that proactive planning, ideally years before mandatory distributions begin, can substantially reduce this burden and keep more of your savings working for you.

This article walks through the mechanics of how RMDs increase taxable income, how that income ripples through the tax code to Social Security and Medicare, and which strategies are most effective for managing the combined impact.

What are RMDs and when must you take them

Required minimum distributions are the mandatory annual withdrawals the IRS requires from tax-deferred retirement accounts once you reach a certain age. The SECURE 2.0 Act moved the starting age to 73 for anyone born in 1951 or later, with a further increase to 75 scheduled for those born in 1960 or later.

Accounts subject to RMDs include:

• Traditional IRAs and rollover IRAs
• SEP-IRAs and SIMPLE IRAs
• 401(k), 403(b), and 457(b) plans from former employers
• Inherited retirement accounts, in most cases
• SIMPLE and SAR-SEP plans sponsored by employers

The IRS calculates your RMD each year by dividing your prior December 31 account balance by a life expectancy factor from the Uniform Lifetime Table in IRS Publication 590-B. For most retirees, the first RMD equals roughly 3.6% to 4% of total retirement account balances. That percentage rises each subsequent year as the divisor shrinks, meaning RMDs automatically grow larger over time even if account balances stay flat.

Roth IRAs carry no RMD requirement during the original owner's lifetime. That distinction is a primary reason the Roth 401k has become such a central tool in retirement income planning. Retirees who built Roth balances during their working years gain the flexibility to control their annual distributions rather than having the IRS impose a mandatory withdrawal floor.

How do RMDs push you into a higher tax bracket

Every dollar of an RMD is treated as ordinary income in the year it is taken. That amount stacks on top of every other income source you receive, including Social Security benefits, pension payments, part-time wages, capital gains, and interest. Together, those sources determine which federal tax bracket applies for the year.

The One Big Beautiful Bill Act, signed July 4, 2025, increased the standard deduction to $15,750 for single filers and $31,500 for married couples filing jointly. Taxpayers aged 65 and older also receive an additional senior bonus deduction of up to $6,000 per qualifying person. These enhanced deductions help, but large retirement account balances still generate RMDs large enough to push many retirees from the 12% bracket into the 22% or 24% brackets.

Consider a married couple, both aged 75, with $1.6 million in combined Traditional IRA balances. Their RMD might total approximately $64,000 that year. With $45,000 in Social Security benefits added, their gross income reaches $109,000 before deductions. After the $31,500 standard deduction and $12,000 in combined senior bonus deductions, their taxable income exceeds $65,000, placing them firmly in the 22% bracket. Any investment income on top of that risks crossing into the 24% bracket.

The bracket effect compounds year after year. As IRA balances continue earning returns, subsequent RMDs grow larger, not smaller, potentially locking retirees into elevated brackets indefinitely without a counterstrategy. Retirees who built up a Health savings account during their working years can use those tax-free funds for Medicare premiums and qualified medical expenses, reducing out-of-pocket healthcare costs without adding to taxable income. Additionally, Tax loss harvesting can offset a portion of RMD income in years with investment losses, providing meaningful relief for retirees who also hold taxable brokerage accounts.

How RMDs increase your Social Security tax bill

One of the less obvious consequences of large RMDs is their effect on Social Security benefit taxation. Under current federal law, up to 85% of your Social Security income can become taxable depending on your combined income. The IRS defines combined income as adjusted gross income, plus nontaxable interest, plus half of your Social Security benefits.

The thresholds that determine how much of your Social Security is taxed are:

1. 50% of benefits taxable: combined income above $25,000 for single filers or $32,000 for married filing jointly
2. 85% of benefits taxable: combined income above $34,000 for single filers or $44,000 for married filing jointly

As detailed in IRS Publication 915, most retirees with meaningful RMDs will exceed both thresholds, meaning that 85% of their Social Security benefits will be taxable income. These thresholds have never been indexed for inflation since Congress introduced them in 1984, so even modest retirement incomes now breach them. A retiree receiving $30,000 in Social Security benefits and taking a $25,000 RMD would see roughly $25,500 of those benefits added to taxable income, a meaningful amount that significantly compounds the bracket pressure described above.

What makes this cascade especially costly is the math of stacking. A $20,000 increase in RMD income does not simply add $20,000 in taxable income. It adds the RMD amount to ordinary income, plus an additional $17,000 or more in now-taxable Social Security benefits, pushing total taxable income up by as much as $37,000 from a single distribution. That stacking effect can push retirees into a substantially higher bracket than their RMD alone would suggest.

Eight states currently tax Social Security benefits in 2026. Retirees should review their 2026 State Tax Deadlines to understand the full picture of what their retirement income costs at the state level, since state taxes compound the federal impact further.

How RMDs trigger IRMAA Medicare surcharges

Beyond federal income tax, RMDs can raise your Medicare Part B and Part D premiums through the Income-Related Monthly Adjustment Amount, commonly called IRMAA. Medicare uses a two-year lookback period, meaning your 2025 income will determine your 2027 Medicare premiums. Taking action to manage modified adjusted gross income this year creates a direct financial benefit two years from now.

The standard Medicare Part B premium for 2025 is $185.00 per month per person. The IRMAA surcharges below reflect the most recently published thresholds. Your 2025 income will determine 2027 premiums, with thresholds expected to adjust upward slightly each year for inflation:

• MAGI $106,001 to $133,000 (single): approximately $74 added monthly per person
• MAGI $133,001 to $167,000 (single): approximately $185 added monthly per person
• MAGI $167,001 to $200,000 (single): approximately $296 added monthly per person
• MAGI $200,001 to $500,000 (single): approximately $407 added monthly per person
• MAGI above $500,000 (single): approximately $444 added monthly per person

For married couples filing jointly, each threshold roughly doubles. A single retiree whose RMD pushes MAGI from $100,000 to $110,000 could pay an additional $888 per year in Part B premiums alone. A married couple crossing the second IRMAA tier pays over $4,400 annually in additional premiums for both enrollees combined, before accounting for any Part D surcharges.

The IRMAA brackets function as income cliffs rather than gradual phase-outs. Crossing a tier by even one dollar triggers the higher premium rate across the entire Part B cost, not just on income above the threshold. This structure creates powerful incentives to manage MAGI precisely and to avoid crossing the next bracket by a narrow margin. Building a Roth 401k balance during working years is one of the most effective long-term solutions, because qualified Roth withdrawals are excluded entirely from the MAGI calculation used for IRMAA.

How to reduce RMD taxes and Medicare surcharges

Proactive planning well before mandatory distributions begin is the most reliable way to reduce the compounding impact of RMDs on taxes and Medicare premiums. The strategies below are most effective when started years ahead of age 73.

Execute Roth conversions during lower-income years

Converting pre-tax retirement funds to a Roth IRA between retirement and age 73 is the single most powerful long-term strategy for reducing future RMD amounts. Paying income tax on converted amounts during lower-income years reduces the balance subject to future mandatory distributions. Smaller future RMDs mean lower taxable income, less Social Security subject to tax, and potentially lower IRMAA exposure two years later. Retirees who convert in systematic annual increments can dramatically reshape their retirement income profile over a decade without triggering bracket spikes in any single year.

Use qualified charitable distributions to satisfy RMDs

Retirees aged 70½ and older can direct up to $108,000 annually from an IRA directly to a qualified charity through a qualified charitable distribution, or QCD. A QCD satisfies the annual RMD requirement but is excluded entirely from taxable income. Unlike a standard charitable deduction, a QCD reduces adjusted gross income before it is used in the IRMAA calculation, making it one of the most efficient tools available for managing Medicare premium exposure. Retirees with multiple IRAs can distribute a QCD from any one account, and married couples can each direct up to $108,000 from their respective IRAs, doubling the potential tax-free charitable transfer in a single year. For retirees with charitable goals, replacing a taxable distribution with a QCD can eliminate thousands of dollars in tax on the same dollar of giving.

Build tax-free income alongside pre-tax balances

Diversifying across account types during working years is the most reliable way to preserve income flexibility in retirement. The Traditional 401k delivers a current-year tax deduction but creates future mandatory distributions. Balancing those contributions with a Roth 401k, which grows tax-free and carries no lifetime distribution requirement, gives retirees the income control that pre-tax-only savers simply do not have. Setting up a Child traditional IRA for younger family members builds tax-efficient wealth for the next generation without exposing them to the RMD pressures that retirement account owners face.

Reduce MAGI with above-the-line deductions

Lowering modified adjusted gross income before the IRMAA calculation applies is the most direct path to reducing Medicare surcharge exposure. Eligible above-the-line deductions include contributions to a Health savings account during years of HDHP coverage and depletion deductions available through the Oil and gas deduction strategy, which higher-income retirees use to generate meaningful income offsets in years with large required distributions. It is also worth noting that MAGI increases from RMDs can affect eligibility for other income-tested benefits. Grandparents who claim Child & dependent tax credits for qualifying grandchildren may find that RMD-driven income increases trigger phase-outs of those credits. Managing MAGI proactively protects multiple benefits, not just Medicare premiums.

Smooth income with early voluntary withdrawals

1. Draw down pre-tax balances voluntarily starting at age 59½, well before mandatory distributions begin.
2. Spread distributions across years to stay below IRMAA tier boundaries and Social Security taxation thresholds.
3. Coordinate capital gain realizations with RMD timing to avoid income compounding in the same tax year.
4. Use Tax loss harvesting to offset RMD income with realized capital losses from taxable brokerage accounts.
5. Review proposed Roth conversion amounts against IRMAA tier boundaries before executing each conversion.

Appeal IRMAA when income drops significantly

If income has declined due to a qualifying life event, such as retirement, the death of a spouse, a loss of pension income, or an employer settlement payment, retirees can request that Medicare use more recent income information by filing Form SSA-44 with the Social Security Administration. This appeal can reduce IRMAA surcharges in the subsequent year rather than waiting for the full two-year lookback cycle to reflect the income change.

Take control of your RMD tax strategy today

Required minimum distributions create a compound planning challenge involving tax brackets, Social Security taxation, and Medicare premiums that becomes significantly harder to address once mandatory distributions have already begun. The most effective strategies, including Roth conversions, income diversification, and charitable distribution planning, require preparation well before the first distribution arrives at age 73.

Instead helps retirees and pre-retirees model the full income impact of required minimum distributions on their tax situation and Medicare costs, so decisions can be made while options are still open. Instead's intelligent system identifies which strategies apply to your specific situation and calculates the projected savings from acting early.

Use Instead's tax savings tools to analyze how your projected RMDs affect taxable income, Social Security benefit exposure, and IRMAA thresholds year by year. Access detailed multi-year projections through Instead's tax reporting features, and explore the plan that fits your retirement situation at Instead's pricing plans.

Frequently asked questions

Q: At what age do required minimum distributions begin in 2025?

A: RMDs begin at age 73 for individuals born in 1951 or later under the SECURE 2.0 Act. For those born in 1960 or later, the starting age increases to 75. The first RMD must be taken by April 1 of the year following the one in which you reach the applicable starting age.

Q: Can I reduce my RMDs to lower my Medicare premiums?

A: Yes. Strategies such as Roth conversions before age 73, qualified charitable distributions, and managing above-the-line deductions can all reduce the MAGI that flows into the IRMAA calculation. Because Medicare uses a two-year lookback period, income management today can lower premiums two years from now.

Q: Do Roth IRA withdrawals count toward IRMAA income?

A: No. Qualified withdrawals from Roth IRAs and Roth 401k accounts are excluded from modified adjusted gross income and do not trigger IRMAA surcharges. This is a primary advantage of building tax-free retirement balances during working years.

Q: What happens if I miss a required minimum distribution?

A: Missing an RMD triggers a 25% penalty on the amount that should have been withdrawn. The penalty decreases to 10% if the missed distribution is corrected within two years through the IRS Self-Correction Program. You must still take the missed distribution and pay ordinary income tax on the full amount.

Q: How do I appeal an IRMAA surcharge when income drops?

A: If income has fallen because of a qualifying life event such as retirement, marriage, divorce, or the death of a spouse, you can file Form SSA-44 with the Social Security Administration to request that Medicare use more recent income information rather than the standard two-year lookback figure.