Required minimum distributions are one of the few elements of a retirement plan that arrive on a fixed government schedule regardless of what you prefer. At age 73, the IRS requires you to begin withdrawing a minimum amount from most pre-tax retirement accounts each year — traditional IRAs, 401(k)s, 403(b)s, and similar accounts. The amount is calculated using the prior year-end account balance divided by a life expectancy factor from an IRS table. You cannot delay it, reduce it below the minimum, or skip it without penalty.
For many retirees, the first RMD is a manageable addition to income. The problem is that RMDs are not static. They increase as a percentage of the account balance each year, and they interact with other income sources in ways that can significantly amplify the tax cost. A retiree who has not planned for this may find themselves at age 75 or 80 with a mandatory income stream that pushes them into higher tax brackets, triggers Medicare IRMAA surcharges, increases the taxable portion of their Social Security benefits, and creates a tax bill substantially larger than anything they experienced during the working years they spent building the account.
Understanding RMDs — how they are calculated, how they interact with the rest of the retirement income picture, and what can be done to manage their impact — is essential planning for anyone with significant assets in pre-tax accounts.
How RMDs Are Calculated
The RMD calculation is straightforward: divide the prior December 31 balance of each pre-tax account by the distribution period factor in the IRS Uniform Lifetime Table corresponding to your age. The resulting amount is your minimum required distribution for the year. For a 73-year-old with a $1 million IRA balance at year-end, the distribution period factor is 26.5, producing an RMD of approximately $37,736.
The distribution period factor decreases each year — reflecting reduced life expectancy — which means the required percentage of the account balance increases annually even if the account balance stays flat. At 73, the factor is 26.5 (about 3.77 percent). At 80, it is 20.2 (about 4.95 percent). At 85, it is 16.0 (about 6.25 percent). At 90, it is 12.2 (about 8.2 percent).
If the account balance also grows because investment returns exceed withdrawals — a common outcome in early retirement when RMDs are small and equity returns are positive — the absolute RMD dollar amount grows faster than the percentage calculation alone would suggest. A $1 million account earning 6 percent annually while paying out $38,000 in the first year will have a higher balance in year two, generating a larger year-two RMD despite the slightly higher withdrawal percentage. This compounding of both the balance and the percentage is the mechanism behind the RMD ratchet effect.
The Tax Cascade: How RMDs Interact With Other Income
The most significant planning implication of RMDs is not their direct tax cost — it is the cascade effect they create on other income sources. When an RMD pushes your total income above certain thresholds, it does not just cost you tax on the RMD itself. It can also increase the taxable portion of your Social Security benefits, trigger Medicare IRMAA surcharges on premiums you are already paying, and push dividends and capital gains into higher rate brackets.
Consider a married couple at age 77 receiving $48,000 in Social Security, $36,000 in CalPERS pension income, and a $65,000 RMD from a combined IRA balance of approximately $1.3 million. Their gross income before deductions is approximately $149,000, with 85 percent of their Social Security taxable. After the standard deduction, their taxable income is roughly $115,000 — squarely in the 22 percent federal bracket, with the first 85 percent of Social Security being taxed. A larger-than-projected market return in the prior year that grew the IRA balance more than expected pushes the following year’s RMD higher still.
For this couple, the effective marginal rate on additional income — accounting for the Social Security taxation interaction — may be closer to 27 or 28 percent rather than the stated 22 percent bracket rate. This “tax torpedo” effect is well-documented in the retirement planning literature and affects a significant share of middle-to-upper-middle-income retirees who do not anticipate it.
The IRMAA Interaction
RMDs interact with Medicare IRMAA surcharges through the same MAGI calculation that governs all IRMAA determinations. A retiree who has carefully stayed below the first IRMAA threshold throughout their early retirement years may find that growing RMDs push them above the threshold in their mid-70s — increasing their Medicare Part B and Part D premiums permanently for as long as the income remains elevated.
Because IRMAA is based on income two years prior, RMDs that begin growing significantly at age 75 affect Medicare premiums starting at age 77. Once the income pattern is established — and it is difficult to reduce RMDs once they have been taken — the IRMAA exposure becomes a recurring annual cost that compounds over years of Medicare enrollment.
This interaction reinforces the case for proactive RMD reduction strategies in the years before distributions become large. The payoff is not just in the Roth account’s tax-free growth — it is also in IRMAA premiums avoided for years.
Strategies to Reduce RMD Impact
The most effective strategies for managing RMD impact work primarily before age 73, during the window when there is still time to reduce the pre-tax balance through conversions or other distributions.
- Roth conversions during the low-income window: As detailed in this month’s first post, converting pre-tax IRA assets to Roth during the years between retirement and age 73 reduces the account balance subject to future RMDs. Each dollar converted now is a dollar whose future RMD is eliminated. For retirees with large pre-tax balances, this is the highest-impact RMD management tool available.
- Qualified Charitable Distributions: IRA owners age 70½ or older can direct up to $105,000 per year (indexed for inflation) from a traditional IRA directly to a qualified charity. A QCD satisfies the RMD requirement to the extent of the distribution but is excluded from taxable income — meaning it does not count toward MAGI for Social Security taxation or IRMAA. For charitably inclined retirees, a QCD is one of the most tax-efficient moves available, effectively allowing the RMD to leave the IRA without ever appearing on the tax return.
- Spending down pre-tax accounts early: Retirees who do not need to minimize current income taxes can draw more heavily from pre-tax accounts in their early retirement years — before RMDs begin — deliberately reducing the balance that will be subject to mandatory distributions later. This strategy is simply accelerating the RMD, on your terms and on your schedule, at whatever rate keeps you in your preferred bracket.
- Employer plan vs. IRA distinction: Required minimum distributions from a current employer’s 401(k) can be deferred beyond age 73 if you are still working and do not own more than 5 percent of the company. For retirees who continue working part-time, this provides limited additional deferral. For all other accounts, the standard rules apply.
The Penalty for Missing an RMD
The penalty for failing to take a required minimum distribution was reduced by the SECURE 2.0 Act from 50 percent to 25 percent of the shortfall — and to 10 percent if corrected within a specified correction window. These are still severe penalties on income you would have owed tax on anyway. Missing an RMD is rarely intentional but occasionally the result of overlooking an account, miscalculating the amount, or failing to account for an inherited IRA’s own RMD schedule. A systematic review of all accounts subject to RMD requirements before year-end each year is the simple administrative fix.
FAQ: Can I Take More Than My RMD to Reduce Future RMDs?
Yes — the RMD is a minimum, not a maximum. You can always withdraw more than the required amount in any given year. Taking more than the minimum reduces the account balance on which next year’s RMD is calculated, which is one form of pre-emptive RMD management. However, additional distributions beyond the RMD are also taxable income in the year taken, so the benefit needs to be weighed against the current-year tax cost. In most cases, a Roth conversion is more tax-efficient than a simple additional distribution, because the converted amount moves into a Roth account where it continues to grow tax-free. A plain additional distribution generates a tax bill without the corresponding future tax elimination. Both strategies reduce future RMDs; the Roth conversion produces a better long-term outcome for most retirees who do not need the additional distribution for current spending.
If you are within ten years of age 73 and have significant assets in traditional IRA or 401(k) accounts, the RMD planning window is open now. Understanding how those distributions will interact with your income picture at 75 and beyond is one of the most financially consequential things you can do with your planning time.
Schedule a complimentary RMD planning consultation with our office. We will project your RMD schedule, model the tax cascade effect against your full income picture, and identify the most effective strategies for your situation to reduce the impact before the mandatory distributions lock in.
