If you retired between 60 and 72 and have a traditional IRA, you are sitting on a tax window most retirees never use. Roth conversions inside the window can shave six figures off your lifetime tax bill. Outside it, you pay full freight when RMDs kick in.
The window closes the year RMDs begin. The math is simple. The decision is not always obvious. Here is how to think about it.
The income valley: why it matters
Most retirement planning focuses on accumulation. How much to save, which accounts to use, how to invest. What gets less attention is the six-to-twelve year window many retirees have between stopping work and starting required minimum distributions (RMDs).
In 2026, RMDs begin at age 73 under SECURE 2.0. If you retire at 62 or 65 and delay Social Security until 70, you may have several years where your taxable income is unusually low. Maybe the lowest it will be for the rest of your life.
That is the window. And it is one of the best tax planning opportunities available to preretirees and recent retirees.
The 2026 specific window dates
For a 62-year-old who retired in 2024:
- No RMDs until age 73, that is 2037
- Social Security delayed until 70, that means relatively low income from 2024 to 2030
- Peak conversion window: roughly 2024-2029
For a 65-year-old who retired in 2025:
- RMDs begin 2034
- If Social Security delayed to 70, income valley runs 2025-2030
- Optimal window: 2025-2029
The specific dates matter because the window closes when RMDs begin. At that point, you may have less room to convert without jumping to higher marginal brackets, and you cannot use RMD dollars to fund conversions.
The marginal bracket math
Here is where conversion decisions get concrete. The 2026 federal income tax brackets for married filing jointly:
- 10%: $0-$23,200
- 12%: $23,200-$94,300
- 22%: $94,300-$201,050
- 24%: $201,050-$383,900
- 32% and above: Over $383,900
A retired couple with $40,000 in Social Security income (85% taxable = $34,000), a $15,000 pension, and no other taxable income has roughly $49,000 in gross income. After the standard deduction of $30,000 for a married couple 65+, their taxable income is around $19,000, in the 10% bracket.
They could convert up to $75,000 of traditional IRA money before their taxable income reaches $94,300 and the 12% bracket ends. Everything above that threshold hits the 22% bracket.
The question is whether paying 12% now beats whatever rate they will pay later when RMDs begin and the conversions are no longer their choice.
How children’s ages affect the decision
If you plan to leave IRA assets to heirs, the analysis shifts. Non-spouse heirs must empty inherited IRAs within 10 years under SECURE 2.0. If your heirs are in their peak earning years during that 10-year window, say ages 45-55 with household income of $200,000+, they will pay tax on your traditional IRA at 24-32%.
Converting at 12% now so your heirs inherit a tax-free Roth instead of a fully taxable traditional IRA is compelling math. The break-even depends on both your current bracket and the expected tax rate of your heirs.
If your heirs are young adults just starting their careers and likely to be in low brackets for many years, the case is weaker.
A simple decision framework
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Calculate your taxable income in retirement, excluding any conversions. Use your Social Security estimate, pension, required distributions from any annuities, rental income, and part-time work.
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Find your top marginal bracket. At that income level, how much room do you have before hitting the next bracket?
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Fill to the top of the 12% bracket. For most retirees in the income valley, filling the 12% bracket each year with Roth conversions is the sweet spot. You pay a low rate and reduce future RMD exposure.
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Model the IRMAA impact. Before converting above $206,000 (individual) or $258,000 (married), check whether you cross into Medicare premium surcharge territory.
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Decide on conversion size and timing. Smaller annual conversions over several years reduce the risk of bracket creep and give you room to adjust if your situation changes.
Open your IRA custodian’s portal this week. Run the conversion estimator. The window is open. It will not be for long.