How Two RMDs at 73 Pushed a Retiree Into the 85% Social Security Tax Trap

A married couple in their early 70s built a $1.4 million traditional IRA. The husband still has a $400,000 traditional 401(k) from an old employer he never rolled over, and they collect $32,000 a year in combined Social Security benefits. For years they kept taxable income low by leaving retirement accounts untouched. Everything changed when they turned 73: the IRS started demanding withdrawals, and the tax picture shifted overnight.

One commenter on a retirement forum said it felt like punishment for saving too well, watching a chunk of Social Security suddenly become taxable just as his first required minimum distribution (RMD) kicked in. As certified financial planner Thiago Glieger explained, “Tax on tax on taxes is the problem we’re trying to solve for here. And it catches people by surprise by the time they get into their 70s.”

The Threshold That Hasn’t Budged Since 1984

The single rule driving this couple’s reality is a formula that determines how much Social Security gets taxed. The IRS adds adjusted gross income (AGI), any tax-exempt interest, and half of Social Security benefits to calculate combined income. For a married couple filing jointly, once that figure crosses $44,000, up to 85% of benefits become taxable. That threshold was set in 1984 and has never been indexed for inflation, which is why it now snares middle-class retirees it was never intended to touch.

Here’s what that looks like in practice. Each retirement account requires its own RMD calculation. Multiple IRAs can be aggregated, but a 401(k) must be calculated separately. Using the 2022 Uniform Lifetime Table divisor of 26.5 for age 73:

1. IRA RMD: $1,400,000 divided by 26.5 equals roughly $52,830 that must be distributed this year.
2. 401(k) RMD: $400,000 divided by 26.5 equals about $15,094, calculated separately and withdrawn from that plan.
3. Combined mandatory withdrawals: $67,924 of ordinary income they didn’t previously have to recognize.

Plug that into the Social Security formula. Combined income becomes $67,924 plus half of $32,000, or $83,924, nearly double the $44,000 ceiling. The result: 85% of their Social Security, about $27,200, gets piled onto their AGI. A benefit they assumed was largely tax-free is now taxed at their marginal rate.

What the Full Tax Picture Resembles

Stack the pieces together and AGI lands near $95,124. The 2026 standard deduction for a married couple filing jointly with both spouses over 65 comes to roughly $35,500, leaving taxable income at around $59,600. That falls inside the 10% and 12% federal brackets, producing a federal tax bill of around $6,800. A real bite for a couple who paid almost nothing the year before.

One bright spot: their modified adjusted gross income (MAGI) sits below the 2026 Income-Related Monthly Adjustment Amount (IRMAA) first tier of $218,000 for joint filers. This means Medicare Part B and Part D premiums remain unaffected by surcharges for now. That cushion shrinks every year the IRA grows and the divisor falls.

Two Levers That Still Work Before Turning 73

The hardest mistake to unravel is doing nothing between the ages of 65 and 72. Once RMDs start, the income is forced. Two moves change the math meaningfully:

1. Roth conversions before 73. Converting traditional balances during low-income years between retirement and the RMD start date shrinks the future base. Pay tax in a 12% bracket now to avoid 22% later, and keep more of Social Security out of the 85% zone permanently.
2. Qualified charitable distributions (QCD) starting at age 70.5. A QCD sends IRA money directly to charity, counts toward the RMD, and never enters AGI. The 2026 limit is $111,000 per person, or $222,000 for a charitably inclined couple. For retirees who already donate, this is the cleanest way to keep combined income under the Social Security threshold.

Banking on the $44,000 threshold to budge is wishful thinking. It has held for over four decades through every cost-of-living adjustment (COLA) Social Security has paid out, and planning around it is more reliable than waiting for Congress.

Details like account mix, charitable goals, and state tax situation all shift the equation from one retiree to the next. The couple above is simply paying for a planning window they didn’t realize was closing. The years before 73 are where the leverage lives, and the choices made then echo through every tax return that follows.