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

A couple retiring at 62 with $1.4 million in traditional IRAs and no pension plans to delay Social Security until age 70 for the largest monthly benefit. Waiting increases the eventual Social Security amount by about 25% to 30%, but it creates a gap between retirement and claiming. During ages 62 through 69, taxable income can be controlled because required minimum distributions have not started. When Social Security begins at 70 and RMDs begin at 73, the two stack and can make up to 85% of Social Security taxable for married couples above about $44,000 of combined income. Roth conversions in the earlier window can move IRA dollars into Roth at lower marginal rates, reducing later tax burdens.

"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."

"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."

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