How Bracket-Filling Roth Conversions Cut This Couple’s Tax Bill by $14,000 a Year

Picture a couple at 62 with $1.4 million in traditional IRAs, no pension, and a plan to delay Social Security until age 70 for the largest monthly check. Their personal balance sheet is healthy. Their worry is the tax bill in retirement, because almost every IRA dollar will come out as ordinary income.

This is where disciplined savers often land. One retiree on a finance forum described it bluntly: we did everything right with the 401(k) and now the IRS is our biggest beneficiary. Waiting until 70 boosts the eventual benefit by 25% to 30%, real money for life, a point underscored in analysis of why supplemental tax-advantaged accounts matter alongside benefits. But waiting creates a window between retiring and claiming, and what happens there can rewrite the tax bill for the next two decades.

The Eight Year Window That Changes Everything

What makes the window between 62 and 73 so valuable is how required minimum distributions (RMDs) interact with Social Security taxation. Once benefits start at age 70 and required withdrawals kick in at 73, the two stack together. Above roughly $44,000 of combined income for a married couple, up to 85% of Social Security becomes taxable, and the marginal rate on the next IRA dollar jumps well above 12%.

Ages 62 through 69 are the only stretch when taxable income is essentially whatever they choose. For 2026, a married couple filing jointly gets a $32,200 standard deduction, and the 12% bracket runs up to $96,950 of taxable income. By converting roughly $77,000 a year from the IRA to a Roth, they stay inside that 12% bracket. Over eight years that’s $616,000 moved out of the tax-deferred bucket at a blended cost of about $73,920 in federal tax.

Without conversions, that same $1.4 million balloons to roughly $2 million by age 70 and produces a first-year required distribution near $77,000. Stacked with $60,000 of combined Social Security, the couple lands around $159,000 of taxable income and a federal bill near $24,500 a year.

With conversions done, the IRA is closer to $1.2 million by age 73. The required distribution falls to about $45,000, taxable income drops to roughly $115,000, and federal tax owed is closer to $12,500. The annual saving is $12,000 to $14,000, repeating for as long as both spouses live.

How the Pieces Fit Together

Conversions only work because Social Security is delayed. If this couple claimed at 62, the 12% bracket would already be partly occupied by taxable benefits, leaving far less room to convert cheaply. Waiting until 70 keeps the bracket empty for nearly a decade and locks in a larger lifetime benefit that, even after taxation, anchors the household budget.

Two practical details decide whether the strategy pays off. The conversion tax should be paid from a regular brokerage account, not from the IRA itself, so the full converted amount keeps compounding tax free. The couple should hold at least a year of living expenses in cash, because selling stocks in a down market to fund a conversion can wipe out the tax savings in a single bad market cycle.

What to Sit With Before Pulling the Trigger

Bracket-filling conversions are not free money. They pull a tax bill forward in exchange for a smaller one later, and the math depends on staying inside the 12% federal bracket. In a high-tax state, the combined cost can erase the advantage. The strategy works best for couples with low state income tax or who plan to relocate. Across a 20-year retirement, tax savings of roughly $240,000 to $280,000 are realistic, with conversions paying for themselves in about six to seven years of retirement.

The costlier mistake is inaction. It is reaching 73, watching the first required distribution land on top of Social Security, and realizing the cheapest tax years of your life have passed you by. Every situation has its own variables, and a conversation with a tax professional who can see the full picture is time well spent.