A Retired Couple Waiting on Social Security Can Convert About $47,500 to a Roth This Year and Owe $0 Federal Tax on It. Most Convert Nothing, Then Pay Tax on the Same Money at 73

A retired couple in their mid-60s who have stopped working but have not yet filed for Social Security occupy an unusual financial position. The paychecks are gone, and the benefit checks have not started. In tax terms, this gap is the most valuable window they will ever have, and it closes fast. Let’s consider a scenario in which a couple converts roughly $47,500 from a traditional IRA to a Roth and owes zero federal tax on the move. The exact number varies by household, but the mechanism does not.

Why the Empty Space Exists

A married couple filing jointly starts with a standard deduction that shields income before calculating tax. For 2026, the base standard deduction for a married couple filing jointly is $32,200, with additional age-based deductions stacked on top. Together, these absorb a substantial slice of gross income before you owe the first dollar of federal tax.

Unused deduction space does not carry forward, and whatever room is left at year-end expires on December 31. That single fact turns the pre-Social Security years into a use-it-or-lose-it opportunity, the quiet stretch we sized up in detail in a free guide to the Roth window.

How a Roth Conversion Works

A conversion is a self-directed move, so the account holder tells the custodian to shift a chosen amount from a pre-tax IRA into a Roth IRA. The amount moved counts as ordinary income for the conversion year, and you owe tax on it at that year’s rates. After the conversion, the money grows tax-free, comes out tax-free in retirement, and is not subject to required minimum distributions during the original owner’s lifetime.

The conversion is voluntary, and the couple decides whether to do one, how much to convert, and when the right time is, which requires some real thinking.

Doing Nothing Is Still a Decision

Money left inside a pre-tax IRA does not stay untaxed forever. At an age that depends on year of birth, mandatory withdrawals begin. The required amount is calculated from the account balance, so a larger balance produces a larger required distribution, and the entire withdrawal is ordinary income in the year it is taken.

By the time those mandatory withdrawals start, Social Security is almost always flowing. The withdrawal stacks on top of benefit checks rather than filling empty space that existed a decade earlier. The same dollars leave the same account, but at a higher marginal rate, in a year the couple didn’t choose, on a schedule dictated by a divisor rather than the household’s plan.

Ripple Effects Worth Knowing

Conversion income shows up in the measure that governs how much of a Social Security benefit becomes taxable. Converting before benefits start keeps that calculation cleaner in later years. For Medicare, the income-related premium surcharge is assessed on income from two years earlier. A couple not yet enrolled in Medicare can convert without risking a surcharge trigger this year. A Roth passed to heirs is a materially different asset than a pre-tax IRA passed to heirs. The beneficiary receives money that has already been taxed and can be drawn without the same income-tax drag.

Where the Strategy Gets Complicated

The senior deduction that helps create this space has an income phase-out and is not permanent under current law, so the size of the window varies household by household and year by year. Converting more than the empty space is a separate decision you should make deliberately. Ideally, the tax comes from outside the retirement account, because paying it from the converted dollars shrinks the amount that actually reaches the Roth.

Anyone buying coverage through the health insurance marketplace before Medicare should also know that conversion income can reduce premium assistance, which can make a conversion more expensive than the tax bill alone suggests. The right conversion amount depends on each household’s specific circumstances.

Bottom Line

The window between the last paycheck and the first Social Security deposit is short, and the deduction space inside it resets every December. A couple that converts nothing has simply postponed the tax into a year with worse terms, when benefits are already flowing, and the withdrawal amount is no longer theirs to set. Those future benefits are still growing, with the 2027 cost-of-living adjustment currently tracking toward 3.1%, which only enlarges the base that future required withdrawals will stack on top of. This is an illustration for educational purposes only.

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