A 73-Year-Old Feared Her RMD Would Drain Her IRA and Tax Her Social Security. The IRS Formula Is Built So It Won’t.

She turned 73 this year, and her IRA custodian’s letter arrived with weight. Her first required minimum distribution (RMD) is due, and weeks of back-of-the-envelope math keep producing the same frightening result: forced withdrawals will drain her traditional IRA, and the extra income will push more of her Social Security into taxable territory. Online forum threads from new retirees in their first RMD year echo that same worry, with the recurring suspicion that the IRS has rigged the rules to empty the account.

The reassurance is right there in the IRS Uniform Lifetime Table. The table is built on a single structural assumption that makes the required withdrawal far smaller than most people expect, and that one design choice also softens the Social Security tax hit.

The Divisor Assumes a Younger Beneficiary

The Uniform Lifetime Table calculates the required withdrawal as if the IRA had a beneficiary exactly 10 years younger than the owner. No such person is required. The IRS bakes that assumption into the math, stretching the payout schedule well beyond any realistic single-life expectancy. At age 73, the exact divisor is 26.5, which produces a required withdrawal of roughly 3.8% of the prior December 31 balance.

Compare that to the Social Security Administration’s actuarial tables, which put a 73-year-old’s remaining life expectancy in the 13-to-15-year range. If the IRS used actual life expectancy, the required percentage would be nearly double. Instead, the rule is structurally generous. The account is designed to last.

The required percentage climbs gradually with age. By 80, the divisor falls to 20.2 and the required withdrawal rises to roughly 5% of the balance. By 85, with a divisor of 16.0, it reaches about 6.25%. Even at those later ages, the math is gentler than a retiree’s actual remaining years would justify. A balance earning a reasonable return through the 70s can still grow in dollar terms while the owner takes the required amount each year.

Why a Smaller Withdrawal Means Less Tax on the Benefit

Social Security taxation works on a sliding scale tied to combined income, which the IRS defines as adjusted gross income (AGI) plus any tax-exempt interest plus half of the Social Security benefit. Once combined income crosses $25,000 for a single filer (or $32,000 for a married couple filing jointly), a portion of the benefit becomes taxable. Above $34,000 for single filers (or $44,000 for joint filers), up to 85% of the benefit can be included in taxable income. That 85% refers to the share added to taxable income, which then gets taxed at the ordinary income rate. It is not a tax rate of 85%.

Because the RMD is smaller than feared, the dollar amount added on top of Social Security is smaller too, which keeps a larger portion of the benefit out of the taxable column. The same logic applies to Medicare. A lower forced income reduces the chance of crossing into a higher Income-Related Monthly Adjustment Amount (IRMAA) tier, which would raise Part B and Part D premiums two years later.

The RMD itself is fully taxable as ordinary income and can pull some additional Social Security into the taxable zone. The divisor’s design caps how severe that effect can be in any single year.

The COLA Effect

The 2026 cost-of-living adjustment (COLA) of 2.8% raised gross Social Security income before any of this tax math applies. That bump matters because the combined-income thresholds for Social Security taxation have not been indexed to inflation since they were set in the 1980s. Every COLA nudges more dollars of benefit into the taxable zone over time, regardless of what the IRA is doing.

A qualified charitable distribution (QCD) lets a retiree send part of the RMD directly from the IRA to a qualifying charity. The transferred amount never appears in AGI. In 2026, the annual QCD limit is $111,000 per taxpayer. For someone who already gives to her church or a cause she cares about, this move can shrink the tax torpedo without requiring more generosity than she already planned.

A New Deduction That Changes the Calculus for Many Retirees

One meaningful development since this article’s original publication: the One Big Beautiful Bill Act, signed into law in July 2025, created a temporary $6,000 bonus deduction per person age 65 and older for tax years 2025 through 2028. A married couple where both spouses are 65 or older qualifies for up to $12,000 in combined additional deductions. The deduction phases out for single filers with modified AGI above $75,000 and for joint filers above $150,000.

The deduction does not change the combined-income formula the IRS uses to determine whether Social Security is taxable. But by reducing taxable income, it can pull many retirees below the thresholds that trigger taxation of their benefits in the first place. For a retiree whose RMD is already modest because of the 26.5 divisor, stacking this new deduction on top of the standard deduction can substantially reduce her federal tax bill on both the RMD and her Social Security.

What Actually Matters

Two points are worth holding onto. First, the IRS designed the Uniform Lifetime Table to preserve the account. The first-year required percentage is small enough that the IRA can keep growing in favorable markets, and the table is calibrated to leave most retirees with a balance well into their 90s. Second, the tax effect on Social Security is bounded by the size of the RMD. Because the required amount is modest, the share of the benefit pulled into taxable territory is modest too. The 85% ceiling applies in extreme cases; most retirees at moderate income levels land well below it.

The mistake hardest to undo is panic-selling assets inside the IRA or withdrawing far more than required because the rules felt threatening. RMD age remains 73 for those born between 1951 and 1959, and 75 for anyone born in 1960 or later, so the timing rules will vary for friends and siblings who ask. A conversation with a tax preparer who has worked through this scenario before can resolve the remaining questions.

Editor’s note: This update adds the specific Social Security combined-income thresholds ($25,000/$34,000 single; $32,000/$44,000 joint), the exact age-73 Uniform Lifetime Table divisor of 26.5, revised age-85 withdrawal rate to 6.25%, the 2026 QCD annual limit of $111,000, and a new section covering the One Big Beautiful Bill Act’s $6,000 senior bonus deduction and its interaction with Social Security taxation for retirees taking RMDs.

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