Roth Conversion After Retirement

Most people assume Roth conversions are a working-years move. You earn less one year, you convert, you move on. What I find in practice is almost the opposite: for many pre-retirees and newly retired clients, the window between the last paycheck and the first required minimum distribution is the single most valuable conversion opportunity they will ever have. The problem is that most people don't recognize the window until it's already closing.

Why Retirement Opens the Conversion Window

The moment you retire, your taxable income often drops to its lowest point in decades. W-2 wages disappear. You may delay Social Security. You're not yet drawing RMDs (which don't begin until age 73 under current law). What's left is investment income, perhaps some part-time work, and whatever you choose to pull from savings.

That gap, sometimes three to ten years wide, is bracketed space. The 22% federal bracket in 2026 runs to $103,350 for married filers. The 24% bracket extends to $197,300. If your combined income sits well below those ceilings, the room between your actual income and the top of a bracket is real estate you can fill with a Roth conversion at a known rate.

Converting in that window means paying tax now, at a rate you can see, rather than later, at a rate you can't. RMDs starting at 73 have a way of stacking on top of Social Security (up to 85% of which may be taxable), capital gains distributions, and anything else that arrives without your permission. The conversion is voluntary. The RMD is not.

The Rules and Tradeoffs Worth Understanding

A Roth conversion is straightforward mechanically: you move money from a traditional IRA or 401(k) into a Roth IRA, and the converted amount is added to your ordinary income for that year. No contribution limits apply. No income cap phases you out. Any amount is eligible.

What makes the math interesting, and dangerous if you ignore it, is what else rises with your income.

IRMAA. Medicare Part B and Part D premiums are means-tested on a two-year look-back. A large conversion in 2026 affects your 2028 premiums. The surcharges are real: a couple crossing the first IRMAA threshold in 2026 (around $212,000 MAGI) pays meaningfully more per month per person for the rest of that two-year period. A single large conversion can trigger thousands of dollars in premium surcharges you didn't account for.

Social Security taxation. If you're already drawing Social Security, a conversion increases your provisional income, which can push more of your benefit into taxable territory. This creates a phantom bracket effect where each additional dollar of conversion income is more expensive than the marginal rate suggests.

The five-year rule. Converted funds must remain in the Roth for five years before the earnings are penalty-free (assuming you're under 59½). If you're already past 59½ and the Roth account itself is at least five years old, this largely stops being a concern. But it matters for anyone who converts and needs liquidity near term.

State taxes. Federal bracket math doesn't include what your state adds. A conversion that looks attractive at the federal level may be less compelling once you factor in state ordinary income tax, especially if you plan to move to a no-income-tax state in the next few years.

The right conversion amount in any given year is the number that fills the bracket efficiently, stops before a cliff (IRMAA threshold, the point where Social Security becomes more taxable), and accounts for what's coming in future years. That's a calculation, not a rule of thumb.

An Illustrative Example

Consider a married couple, both 66, recently retired. They're delaying Social Security until 70. Their only income is $30,000 in portfolio dividends. They have $1.4 million in a traditional IRA and $200,000 in a taxable brokerage account.

In this scenario (illustrative only, not a specific client), their taxable income before conversions is well below the top of the 22% bracket. They have roughly $70,000 of bracket space before reaching the 24% threshold, and more before the first IRMAA cliff. A disciplined four-year strategy of converting $60,000 to $70,000 annually could move $240,000 to $280,000 into Roth before RMDs begin at 73, at a known blended rate in the low-to-mid twenties percent range.

Done without a plan, a single $300,000 conversion in year one might save taxes in theory while triggering IRMAA surcharges, pushing Social Security income into higher taxation, and creating a large tax bill in April with no withholding offset. The lever is real. The sequencing is what makes it work.

How This Connects to the Roth Conversion Strategy

The mechanics I've described here are one slice of a larger picture. The decision to convert after retirement sits squarely in what I call the Harvest stage of a well-built plan: the years when the discipline is not accumulation but tax-aware withdrawal sequencing. The question is never simply "should I convert?" It's "convert how much, in which years, against which other income events, and in which accounts?"

For the full picture on bracket math, the ACA interaction, and how conversions fit into a coherent pre-retirement strategy, I'd point you to our parent guide: Roth Conversion: A Practical Guide for High Earners and Pre-Retirees. The cluster of decisions around timing, amount, and account type is covered there in more depth.

Frequently Asked Questions

Is there an age limit on Roth conversions after retirement?

No. There is no age limit on converting traditional IRA or pre-tax 401(k) funds to Roth. Even after you begin taking RMDs at 73, you can convert additional amounts beyond the required minimum. (You cannot convert the RMD itself, but anything above the RMD is eligible.)

Do I have to pay the tax from the converted amount, or can I pay it separately?

You can pay the tax from outside funds, which is generally the better approach. If you withhold taxes from the converted amount itself, that withheld portion never reaches the Roth and the tax benefit shrinks accordingly. Paying from a taxable account preserves the full conversion value inside the Roth.

Does a Roth conversion affect my Medicare premiums?

Yes, through IRMAA. Medicare uses your MAGI from two years prior to set Part B and Part D premiums. A conversion that pushes you above an IRMAA threshold in 2026 will affect your 2028 premiums. This should be modeled before you convert, not discovered afterward.

What happens to my Roth conversion if tax rates change?

A Roth conversion is a bet that future rates, or your future effective rate, will be higher than today's rate on the converted amount. If rates fall significantly, the conversion was less valuable than it appeared. Most planning assumes current rates are near historical lows for high earners, but no one can guarantee what Congress does next.

Can I undo a Roth conversion if I change my mind?

No. Recharacterization of Roth conversions was eliminated by the Tax Cuts and Jobs Act in 2018. A conversion is permanent in the tax year it occurs. This makes the upfront calculation more important, not less.

Does a Roth conversion count as income for ACA subsidy purposes?

Yes. If you purchase insurance through the ACA marketplace before Medicare eligibility at 65, a large conversion can push your MAGI above the subsidy cliff. For pre-retirees aged 60 to 64 still on marketplace coverage, this is one of the most commonly overlooked conversion watchouts.

What to Do Next

1. Pull your most recent tax return and identify your current MAGI and how much bracket space sits between your income and the next meaningful threshold (24% bracket top, first IRMAA cliff).
2. Project your income from age 73 forward: estimated Social Security, RMD amounts from your pre-tax accounts, and any other expected sources. That picture tells you what the problem is if you do nothing.
3. If the gap between now and 73 is at least three years and your pre-tax balance is substantial, a year-by-year conversion model is worth building. That's where a fiduciary advisor earns the conversation.
4. If you're not working with an advisor yet, use the analysis above as a checklist to pressure-test any proposal you receive. The right plan will account for IRMAA, Social Security taxation, and state taxes, not just the federal bracket math.

The information provided is for educational purposes only and does not constitute investment, legal, or tax advice. Tax law changes frequently — verify current rules before acting. Consult with qualified professionals for guidance specific to your situation.