The Roth Conversion Window Between Retirement and Social Security

If you retire at 62 or 63 and don’t claim Social Security until 67 or 70, something quietly extraordinary happens to your tax return. Your W-2 income drops to zero. Your Required Minimum Distributions are a decade away. And for the first time in your adult life, your taxable income temporarily collapses into the bottom two brackets — sometimes into nothing at all.

That collapse is the most underused tax planning opportunity in retirement. It’s a window of three to seven years where the marginal cost of converting traditional IRA money into a Roth IRA is the lowest it will ever be. And most retirees walk through it without converting a dollar.

This is the conversation most pre-retirees never have with anyone. Here’s what the window is, why it exists, and how to use it without tripping the cliffs that close it early.

What the window actually is

The “Roth conversion window” describes the years between your last earned paycheck and the start of your fully-on retirement income. The boundaries vary by household, but the shape is consistent: you’ve stopped working, you haven’t claimed Social Security yet, and your tax-deferred accounts haven’t started forcing distributions because RMD age (currently 73, climbing to 75 in 2033 under SECURE Act 2.0) hasn’t arrived.

Inside that window, your taxable income is unusually low. You might be living on cash, taxable brokerage proceeds, a small pension, or a partial part-time wage — anything that doesn’t push you into a high bracket. The IRS still wants its income tax. But because your reported taxable income is so low, the brackets you’re filling are the cheapest brackets on the schedule.

That’s the asymmetry. A dollar of traditional IRA you convert now might cost you 12 cents in federal tax. The same dollar converted later — once Social Security and RMDs are both turned on — can cost 22, 24, or even 32 cents. The window is the period when those two prices diverge most.

Why those years are tax-cheap

A married couple filing jointly in 2026 gets a standard deduction north of $30,000. The 10% bracket runs from there to roughly $23,850 of taxable income. The 12% bracket runs up to about $96,950. Then it jumps to 22%.

For a 64-year-old couple who retired last year and hasn’t yet claimed Social Security, this means the first roughly $127,000 of any Roth conversion is sitting in the 10% and 12% brackets — assuming no other income. They could convert nearly that much from a traditional IRA each year, pay around $11,000 in federal tax, and never break the 12% bracket.

Compare that to what happens after age 70 if both spouses delayed: a combined Social Security benefit of $80,000, RMDs of $40,000 from a still-large traditional IRA, plus whatever taxable interest the cash bucket throws off. Suddenly the same conversion sits squarely in the 22% or 24% bracket. The math gets worse the longer you wait.

This is why the Roth conversion strategy interacts so directly with Social Security taxation — and why doing conversions before you claim is fundamentally cheaper than after. Once Social Security is turned on, every conversion dollar drags additional benefit dollars into taxable territory through the provisional income formula, layering a second tax on top of the first.

Thomas’ Take. I think about the Roth conversion window the same way I think about Social Security claiming: most retirees focus on the year they retire, when the real action is in the five to seven years after. The decisions that look small in your early sixties — convert how much, claim when, draw from where — compound into the biggest tax differences in your retirement plan. Doing nothing in the window isn’t “playing it safe.” It’s choosing the higher tax bill later by default.

A hypothetical: Eleanor, 64, looking at the next six years

Consider a hypothetical case: Eleanor, 64, just retired from a 30-year teaching career in Charlotte. She has $620,000 in a traditional 403(b), $90,000 in a Roth IRA, $140,000 in a taxable brokerage, and a small state pension of $1,400 per month that started this year. Her plan is to wait until 70 to claim Social Security to maximize the survivor benefit for her husband Marcus.

Without any conversions, here’s how her next six years look. From 64 to 69, her taxable income is the $16,800 pension plus whatever she draws from the brokerage for living expenses. After the standard deduction, she’s barely above zero on most years. Then at 70, Social Security flips on — roughly $44,000 a year. At 73, RMDs start. Her traditional account has grown over the intervening years, and her first RMD is around $30,000. Suddenly her taxable income is closer to $90,000, and her marginal rate is 22%.

Now run the version where she converts. In each of those six low-income years, Eleanor moves $50,000 from her traditional 403(b) — rolled to a traditional IRA — into a Roth IRA. Her total tax on each conversion is roughly $5,000, about 10%. Over six years she’s converted $300,000, paid about $30,000 in tax, and reduced her future RMD base by roughly that same $300,000 plus whatever it would have grown to.

When RMDs start at 73, her required distribution is materially smaller — sometimes by a third — because her traditional balance is smaller. She’s also built a Roth bucket that doesn’t generate any taxable income, can fund discretionary spending in a high-income year, and passes to her heirs tax-free. The “cost” of the conversion was a tax bill she would have eventually paid at a higher rate.

The exact numbers in your situation will differ. The shape doesn’t.

Four traps that close the window faster than people realize

The window is real, but it’s narrower than the raw bracket math suggests. Four common pitfalls shrink it.

IRMAA. Once you turn 63, your Modified Adjusted Gross Income two years prior starts determining your Medicare Part B and Part D premiums. In 2026 the first IRMAA threshold for couples is around $212,000 of MAGI. A large Roth conversion that pushes you above a threshold triggers premium surcharges on both spouses for the entire following year, and those surcharges scale up sharply. Roth conversions count as MAGI. The CMS Medicare premium thresholds are published annually and worth checking before sizing a conversion in your early sixties.

ACA subsidies. If you’re retired and on a marketplace health plan before Medicare kicks in at 65, your premium subsidy is based on MAGI. A Roth conversion can blow up the subsidy and turn a $300-a-month plan into a $1,500-a-month plan. The math may still favor converting, but it needs to be modeled, not assumed.

Social Security taxation. If you’ve already started Social Security inside your window — say at FRA but before RMDs — the provisional income formula taxes up to 85% of your benefit once your other income clears modest thresholds. A conversion that adds $50,000 of taxable income often drags an additional $42,500 of Social Security into the taxable pile, creating an effective marginal rate well above the headline bracket. The SSA publishes the provisional income formula — and it hasn’t been updated for inflation since 1984, which is why the thresholds bite more retirees every year.

State income tax. A handful of states tax Roth conversions at full income rates with no retirement-account exclusion. If your plan is to move to a no-income-tax state (Florida, Tennessee, Texas) in a few years, the conversion math sometimes argues for waiting until you’ve established residency there.

How much to convert — fill the bracket, don’t break it

The cleanest framework for sizing a conversion is to fill a target bracket and stop. For most retired couples in their early sixties, that bracket is the 12% bracket. You estimate your existing taxable income for the year, look at how much room is left until the top of the 12% bracket (roughly $97,000 for joint filers in 2026), and convert exactly that amount. No more, no less.

If you have more traditional IRA than six years of bracket-filling can convert, you reach into the 22% bracket — but only as far as the math justifies, and only after pressure-testing for IRMAA. Once you’re approaching age 63, the IRMAA two-year lookback becomes a hard ceiling for most planners.

This is also why the order in which you draw from your accounts matters so much. Pulling living expenses from your taxable brokerage during the window leaves more bracket space for conversions. Pulling from the traditional IRA closes that space and forces you to choose between living and converting.

The window is the cheapest tax planning real estate in retirement. The price of the conversion is fixed at today’s brackets. The cost of not doing it is paid later, at brackets you don’t get to set.

Key takeaways

• The Roth conversion window is the gap between your last paycheck and the start of Social Security plus RMDs. For most early retirees, it’s three to seven years long.
• Inside the window, your marginal tax rate often sits in the 10% or 12% bracket, making conversions materially cheaper than they will be later.
• IRMAA, ACA subsidies, Social Security taxation, and state income tax all narrow the window. Size conversions against the binding constraint, not just the federal bracket.
• The cleanest sizing rule is to fill the 12% bracket and stop, then reassess each year.
• The window is also why bucket planning and account ordering matter so much in your early sixties — they decide whether the window stays open.

FAQ

Should I still convert after claiming Social Security?
Sometimes yes, but the math changes. Provisional income taxation can push the effective marginal rate well above the headline bracket, so a 22% bracket conversion can cost closer to 27%. Modeling matters more here than in the pre-claiming years.

What if I’m working part-time?
A small wage doesn’t close the window — it just narrows it. Use your part-time income plus pension as the starting taxable-income figure, then convert into whatever bracket space is left.

Does the five-year clock matter for retirees?
The five-year clock on converted amounts applies before age 59½ to avoid the 10% early-withdrawal penalty. For anyone over 59½ doing planned conversions in their sixties, the clock is rarely a binding constraint, but the converted earnings still need to season to be qualified.

This article is published by Confluence Media Group LLC, an independent publisher of educational financial content. Thomas Clark is a Series 65 Investment Advisor Representative. The information provided is for educational and informational purposes only and is not personalized financial, tax, or legal advice. Past performance does not guarantee future results. All investing involves risk, including potential loss of principal. Consult a qualified professional before making financial decisions.

Confluence Media Group LLC is a separate entity from Confluence Capital Management, the investment advisory practice through which Thomas Clark provides advisory services. Advisory services are not offered through this publishing platform.

About Thomas Clark

Thomas Clark is the founder of Confluence Media Group LLC and a Series 65 Investment Advisor Representative. He has spent nearly two decades working with families on retirement planning, with a focus on Social Security optimization, retirement income coordination, and the bucket planning approach to building a guaranteed income floor.

Thomas writes and publishes at thomasclarkadvisor.com and is the author of The Just in Case Binder — a 148-page printable family financial organizer for households who want to make sure the people they love know where everything is.

He lives in North Carolina with his family.

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Thomas Clark

Thomas Clark is a Series 65 licensed investment advisor and experienced trader. He specializes in investing, retirement planning, and market analysis, helping individuals build wealth and make informed financial decisions.