A 62-year-old who spreads a $400,000 Roth conversion across 11 years pays about $48,000 in federal tax at 12%, saving roughly $24,100 compared with a 70-year-old who has only three years to convert.
The older couple’s compressed annual conversion of $133,333 pushes $80,333 into the 22% bracket each year and leaves income just $4,667 below the level that could trigger higher Medicare premiums.
Under SECURE 2.0, the 70-year-old must begin RMDs at 73, leaving three conversion years, while the 62-year-old is covered by the age-75 rule and has a window through age 74.
Two hypothetical married couples each have $400,000 in a traditional IRA and want to move the full amount into a Roth IRA before required minimum distributions, or RMDs, begin. In one case, the retiree is set to turn 62 in 2027. In the other, the retiree turns 70 the same year. Although both couples start with the same balance and face the same tax brackets, their conversion tax bills diverge sharply because they have very different numbers of years to spread the income.
Every dollar converted is treated as gross income in the year it is moved under 26 U.S.C. § 408A(d)(3)(A)(i). Roth IRAs do not have lifetime withdrawal requirements, unlike traditional IRAs, so the main issue is how much income gets stacked into each available year. With fewer years to work with, the annual conversion amount rises and can spill into higher brackets.
How SECURE 2.0 Shapes Each Deadline
Under current IRS rules, someone who reaches 72 after 2022 and 73 before Jan. 1, 2033 has an RMD age of 73. Someone who reaches 74 after Dec. 31, 2032 has an RMD age of 75. The 70-year-old reaches 73 in 2030, which leaves 2027 through 2029 as the available conversion years. The 62-year-old falls under the age-75 provision.
Running the Same $400,000 Through Current Brackets
The comparison uses the 2026 federal tax brackets for married couples filing jointly. For that year, the standard deduction is $32,200. The 12% bracket applies to taxable income above $24,800, and the 22% bracket begins above $100,800. To keep the example simple, this assumes no investment growth in the IRA and leaves out the separate senior deduction added by OBBB.
For the 62-year-old couple, assume $60,000 in other income from a pension or part-time work, which puts taxable income at $27,800 before any conversion. Converting roughly $36,364 per year raises taxable income to about $64,164, keeping the entire amount within the 12% bracket.
For the 70-year-old couple, Social Security has likely already started. In 2027, the Social Security Administration estimates the average benefit for an aged couple both receiving benefits at $3,355 per month after a 3.6% cost-of-living adjustment. This couple is assumed to have $80,000 in other taxable income, leaving $53,000 of room in the 12% bracket. Converting about $133,333 a year fills that space, and the rest is taxed at 22%.
Measure | Turning 62 | Turning 70 |
|---|---|---|
Annual conversion | $36,364 | $133,333 |
Taxed at 22% each year | $0 | $80,333 |
Federal tax per year | $4,364 | $24,033 |
Total tax on $400,000 | $48,000 | $72,100 |
For the older couple, about 60% of each year’s conversion is taxed at 22%. Over the full conversion, that adds up to roughly $24,100 more in federal tax on the same $400,000 balance.
Medicare Premiums Are Close Behind the Larger Conversions
Each year of the more compressed conversion puts the 70-year-old couple’s income at about $213,333. That is roughly $4,667 below the 2026 joint-filer threshold of $218,000.
Above that level, each spouse’s Part B premium rises from $202.90 to $284.10 a month. Slightly more other income, or some investment growth inside the IRA, could push the couple over the line. The younger couple’s income of about $96,364 leaves a much wider cushion.
Where Retirement Account Money Sits by Age
The Federal Reserve’s Distributional Financial Accounts show that households headed by someone aged 55 to 69 held 49.5% of defined contribution and annuity assets in the second quarter of 2026. Households headed by someone aged 70 and older held 9.4%. Those figures cover the entire household sector and do not describe any one family’s accounts.
What Could Change the Picture
This comparison depends on assumptions that can shift over time. Social Security benefits rise with each cost-of-living adjustment, which increases the income base for retirees already collecting. Tax brackets also move up with inflation each year. Future tax rates, the loss of a spouse that moves the survivor into single-filer brackets, and heirs’ tax rates can all affect whether a Roth conversion makes sense.
A recent MarketWatch article noted that people who worry about missing out on Roth conversions may be giving up less than they think. Each new inflation adjustment to brackets and benefits resets the income base that a household builds on top of.
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