The Roth Conversion Window: After Work, Before RMDs
Updated May 2026
The Roth conversion window is the stretch after you stop working but before required minimum distributions begin, often roughly age 60 to 73. Income is typically lower, control over taxable income is higher, and converting traditional IRA or 403(b) dollars to Roth at today's rates can shrink future RMDs, reduce future Medicare IRMAA exposure, and potentially improve after-tax wealth transfer to heirs. It can also create real tax cost and trigger an IRMAA cliff if mistimed.
This piece walks through how the window works, what a conversion costs today versus what it can save later, how IRMAA and Social Security claiming change the math, when conversions are a poor fit, and how to think about sizing year by year. It is written for retirees and pre-retirees who have meaningful balances in traditional 401(k), 403(b), or IRA accounts, including the Mayo Clinic employees and retirees we work with most. The views in this blog are the views of Fortress Financial and not the views of Mayo Clinic. Mayo Clinic and Fortress Financial Group are not affiliated.
What is the Roth conversion window?
The Roth conversion window is a planning term, not an IRS term. It refers to the period between two events: the last year of your working income, and the first year of mandatory withdrawals from your tax-deferred accounts. For most retirees today, that means the years between roughly 60 and 73.
Under SECURE 2.0, required minimum distributions (RMDs) generally start in the year you turn 73 if you were born between 1951 and 1959, and the year you turn 75 if you were born in 1960 or later. RMDs apply to traditional IRAs, SEP and SIMPLE IRAs, and most workplace plans like 401(k)s, 403(b)s, and 457(b)s. They do not apply to Roth IRAs, and beginning in 2024 they no longer apply to designated Roth accounts inside 401(k) and 403(b) plans during the original owner's lifetime. Source: IRS, "Retirement topics, Required Minimum Distributions".
In our work with Mayo retirees, this window is usually the first three to ten years after separation. The Mayo pension may have started, the 403(b) is sitting untouched, the 457(b) is being drawn down, and Social Security is often deferred. That combination is one reason retirees may evaluate conversions during this period.
Why are post-retirement years often the lowest-income years?
When the W-2 paycheck stops, taxable income usually drops sharply, and you gain real control over what hits your return. A typical pre-retirement year might include $200,000 of wages, taxable interest, and capital gain distributions. The first year fully retired might be a Mayo pension annuity of $40,000, modest interest, and nothing else, until you choose to add to it.
The 2026 standard deduction is $32,200 for married couples filing jointly and $16,100 for single filers. Couples both age 65 or older add another $1,650 each. There is also a temporary $6,000 senior bonus deduction per qualifying taxpayer age 65 and over, available for tax years 2025 through 2028, that phases out above $75,000 of MAGI for singles and $150,000 for joint filers. Source: IRS, "IRS releases tax inflation adjustments for tax year 2026".
For a 67-year-old couple with $40,000 of pension income and standard deductions, the math works like this: gross income of $40,000, standard deduction plus age add-ons of roughly $35,500, taxable income of roughly $4,500. That is well inside the 10% bracket. There is significant room before they reach the top of the 12% bracket ($100,800 of taxable income MFJ in 2026), the 22% ($211,400), or the 24% ($403,550). Each of those ceilings is a possible conversion target.
How does a Roth conversion reduce future RMD pressure?
A Roth conversion moves money from a traditional retirement account to a Roth account. The conversion itself is taxable. The result is that you have a smaller traditional balance going forward, which means smaller future RMDs, which means less forced taxable income at 73 or 75 and beyond.
Consider a simplified example. A 65-year-old has $1,000,000 in a traditional IRA. If she does nothing, by age 73 her balance might grow to roughly $1,470,000 at a 5% return. Her first RMD at 73 would be that balance divided by 26.5 (the IRS Uniform Lifetime Table factor for age 73), or about $55,500 of forced taxable income that year, growing each year afterward.
If instead she converts $50,000 per year for eight years between 65 and 72, her traditional balance at 73 might be roughly $1,000,000, depending on returns and how the tax is paid. Her first RMD then becomes about $37,700. Over a 25-year retirement, the cumulative reduction in forced taxable income is substantial, and the converted dollars compound tax-free in the Roth from the day of the conversion forward.
The key insight: RMDs are a percentage of the traditional balance. Anything that shrinks that balance, before age 73, shrinks every future RMD. For more on related tax-side moves, see our companion piece on retirement tax moves that may result in paying less.
What does a Roth conversion cost today?
A conversion is treated as a distribution from the traditional account and ordinary income on your tax return. There is no 10% early withdrawal penalty on the converted amount, regardless of age. But the converted dollars stack on top of any other taxable income that year and fill brackets accordingly.
A few principles we work with. The marginal rate on the conversion is what matters, not the average. If the next dollar of conversion is taxed at 22% but you expect to be in the 24% bracket in retirement, the conversion is favorable. If the next dollar is at 24% and you expect to drop to 22% later, it usually is not.
Pay the tax from non-IRA money if you can. If you withhold the tax from the conversion itself, fewer dollars actually land in the Roth and the math gets weaker. Cash, taxable brokerage, or proceeds from a sale work better as the funding source for the tax bill.
You cannot undo a conversion. Recharacterization of conversions was eliminated by the 2017 Tax Cuts and Jobs Act, which the One Big Beautiful Bill Act made permanent. Once you convert, you owe the tax. For other ways retirees get blindsided by the tax code, see why so many retirees are blindsided by taxes.
How do conversions interact with Medicare IRMAA?
This is where careful clients get tripped up. Medicare's Income-Related Monthly Adjustment Amount (IRMAA) is a surcharge added to Part B and Part D premiums when modified adjusted gross income (MAGI) exceeds certain thresholds. For 2026, IRMAA begins at $109,000 for single filers and $218,000 for joint filers, with the standard Medicare Part B premium at $202.90 per month before the surcharge. Source: Centers for Medicare & Medicaid Services, "2026 Medicare Parts A & B Premiums and Deductibles."
Two features make IRMAA painful in conversion years. First, it uses a two-year lookback: your 2026 IRMAA is determined by your 2024 MAGI, so a Roth conversion done in 2026 affects your 2028 Medicare premiums. Second, it is a cliff, not a phase-in. One dollar of MAGI over a threshold triggers the full surcharge for that tier, for both spouses if both are on Medicare. The first tier above $218,000 MFJ adds roughly $2,300 per year for a couple on top of regular premiums.
When we plan multi-year conversions for clients on or near Medicare, we project MAGI for each year of the ladder and check the IRMAA implication two years downstream. The pre-Medicare years (typically 60 to 64) are particularly attractive because conversions in those years carry no IRMAA exposure.
If income drops because of a qualifying life event, most commonly retirement, Form SSA-44 lets you appeal a current IRMAA determination. A recently retired client who shows a full year of W-2 income on the 2024 return that drives 2026 premiums may be able to request reconsideration using projected current-year income. For a wider view of the RMD, Social Security, and IRMAA traps that compound this problem, see 3 retirement tax traps to avoid.
How does a Roth conversion interact with Social Security claiming?
Social Security benefits are taxed based on "provisional income" thresholds that have not been indexed for inflation since the early 1990s. For joint filers, up to 50% of benefits become taxable at $32,000 of provisional income, and up to 85% above $44,000. For singles, the thresholds are $25,000 and $34,000.
A Roth conversion increases provisional income dollar for dollar. If you have already claimed Social Security, conversions can quickly push more of the benefit into the 85% taxable zone, which raises the effective rate on the conversion above its statutory bracket. That is the "tax torpedo" effect.
One planning approach some retirees consider is delaying Social Security until 70 and use the gap years to do larger conversions before benefits start. Delayed claiming also produces larger lifetime benefits (8% per year of delayed retirement credits between full retirement age and 70), which is a separate consideration. For a deeper look at the claiming decision, see our guide on when to take Social Security.
When should you not convert?
Five common reasons we tell clients to skip a conversion year, or skip conversions entirely.
You expect to be in a meaningfully lower bracket in the future. The whole strategy depends on paying tax now at a lower rate than you would pay later. If retirement spending will be modest and you have no large taxable income sources coming, the future bracket may stay below today's.
You will need the converted money within five years and you are under 59½. Each conversion has its own five-year clock for penalty-free withdrawal of the converted principal before age 59½. Past 59½ this rule is less of a constraint, but the broader Roth ordering rules still matter.
The conversion would push you over an IRMAA tier. The two-year lookback means the surcharge can ambush a conversion that looked fine on the federal return alone.
You are a heavy charitable giver and plan to use Qualified Charitable Distributions (QCDs) once eligible. Starting at age 70½, you can satisfy part or all of an RMD by sending money directly from an IRA to charity, with no income recognition. For someone giving $20,000 a year to charity from age 70½ onward, traditional IRA dollars going out as QCDs are essentially never taxed. Converting those dollars first wastes that benefit.
You do not have non-IRA cash to pay the tax. Withholding the tax from the conversion is allowed, but it leaves fewer dollars in the Roth and weakens the long-term math, especially for clients under 59½ where the withheld portion may itself face penalties.
What about Mayo retirees specifically?
For the Mayo Clinic employees and retirees we work with, a few specifics shape the conversion conversation.
The Mayo 403(b) Plan permits in-plan Roth rollovers for participants who are eligible to receive an in-service withdrawal, who are over 59½, or who have separated from service. That means you can convert without rolling out to an IRA, if you prefer. Source: Mayo 403(b) Plan Summary Plan Description (January 2026), pages 13 to 14.
Mayo Pension payment timing matters. If you elected a lump sum from the Mayo Pension Plan and rolled it to an IRA, that IRA balance becomes part of the conversion-eligible pool. If you elected an annuity, it shows up each year as ordinary income that fills your brackets before any conversion lands on top.
For retirees who elected the Stable Lump Sum formula during the 2023 Mayo Retirement Choice window, a lump sum in the same year as planned conversions is usually a mistake. The lump sum itself, if not rolled, lands as a giant taxable spike. Sequencing matters: pension event in one year, conversions in subsequent years.
The window between Mayo separation and Social Security claiming is often where the heaviest conversion lifting happens for our clients. A 62-year-old who retires from Mayo, defers Social Security to 70, and has $1.5 million of pre-tax balances may be a strong candidate for evaluating Roth conversions. For the broader Mayo benefits picture, see our Mayo 403(b) plan guide.
How much should you convert each year?
There is no single right answer, but two common framings work well together.
Bracket-fill: convert up to the top of a chosen bracket. For 2026, the top of the 12% bracket for joint filers is $100,800 of taxable income, the top of the 22% is $211,400, and the top of the 24% is $403,550. A common target is filling the 22% or 24% bracket, depending on the size of the traditional balance and the future bracket projection.
IRMAA-aware: stay below the relevant IRMAA tier two years out. For most clients we cap conversions so that MAGI lands $5,000 to $10,000 below the next threshold to leave room for unexpected interest, dividends, or capital gains.
A multi-year ladder usually beats one large conversion. Spreading $400,000 of conversions across five years at $80,000 a year is almost always more tax-efficient than $400,000 in a single year, because brackets and IRMAA tiers refill annually.
| Filing Status | Top of 12% Bracket (2026) | Top of 22% Bracket (2026) | Top of 24% Bracket (2026) |
|---|---|---|---|
| Married Filing Jointly | $100,800 | $211,400 | $403,550 |
| Single | $50,400 | $105,700 | $201,775 |
Source: IRS Revenue Procedure 2025-32. These are taxable income thresholds, not MAGI.
For broader context on the recent batch of retirement rule changes that frame this conversation, see the retirement rules changed again.
What this means for you
The Roth conversion window is one of the highest-impact planning tools in retirement, and one of the easiest to misuse. Done well, it shrinks future RMDs, may improve long-term tax flexibility, reduces future IRMAA risk, and leaves Roth dollars to grow tax-free for the rest of your life and your heirs' next decade. Done poorly, it accelerates tax for no reason and can trigger Medicare surcharges that recur every year you stay above a threshold.
For most retirees, the right answer is not "convert everything" or "do not convert." It is "build a multi-year plan, start small, watch IRMAA, and revisit each year as facts change." For a wider Rochester-focused tax view, see our overview of taxes in retirement.
Frequently asked questions
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 of 2017 and made permanent by subsequent legislation. Once a conversion is processed, the tax is owed for that year. You can stop future conversions at any time, but the one already done is final.
What is the five-year rule on Roth conversions?
Each Roth conversion has its own five-year clock that determines whether the converted principal can be withdrawn before age 59½ without a 10% penalty. If you are already 59½ or older, the conversion-specific five-year rule for principal withdrawals does not apply. A separate five-year rule applies to whether earnings on Roth dollars come out tax-free, which begins with your first Roth contribution or conversion.
Are Mayo 403(b) Roth conversions different from IRA conversions?
Mechanically they are similar: pre-tax dollars become Roth dollars, and the converted amount is taxable in the year of conversion. The Mayo 403(b) Plan permits in-plan Roth rollovers for eligible participants. Some clients prefer to roll the 403(b) to an IRA at separation and convert from there, mainly for investment flexibility. Either path produces the same federal tax outcome.
When does a Roth conversion actually reduce my heirs' taxes?
Most non-spouse beneficiaries who inherit a traditional IRA must empty it within 10 years under the SECURE Act rules. Distributions from the inherited traditional account are taxable to the heirs at their own marginal rates. An inherited Roth IRA also follows the 10-year rule, but withdrawals come out tax-free if the original 5-year rule was met. For an heir in their peak earning years, this can be a meaningful difference.
Does a Roth conversion count toward my RMD?
No. RMDs and Roth conversions are separate transactions. If you are RMD age, you must take the full RMD as a taxable distribution before any conversion, and the RMD itself cannot be converted to a Roth. Conversions can happen on top of the RMD but not in place of it.
How do I know if a conversion makes sense for my situation?
The honest answer is that it depends on the projected difference between your current marginal rate and your future marginal rate, your IRMAA exposure, your charitable plans, and your time horizon. A simple rule of thumb: if you are confident your future bracket will be higher than today's, conversions may be worth evaluating. If you are confident it will be lower, they usually are not. Most retirees fall somewhere in between, which is where running real multi-year projections earns its keep.
Disclosures
Disclosures
This article is for educational purposes only and does not constitute personalized investment, tax, legal, or financial advice. The information provided is general in nature and may not apply to your specific situation. Please consult with a qualified financial advisor, tax professional, or attorney about your individual circumstances before making any financial decisions.
Fortress Financial Group is a Registered Investment Adviser. Registration does not imply a certain level of skill or training. Fortress Financial Group operates as a fee-only fiduciary.
Tax content
Tax laws and regulations change frequently. The information in this article reflects rules in effect as of May 2026 and may not reflect subsequent changes. Tax outcomes depend on your specific situation. Consult a qualified tax professional before making decisions based on tax considerations.
Social Security content
Social Security claiming decisions involve numerous factors specific to your situation, including health, marital status, work history, and other income sources. The Social Security Administration is the authoritative source on benefit calculations and eligibility. Visit ssa.gov or speak with a qualified advisor before making a claiming decision.
Medicare and IRMAA content
Medicare rules, premiums, and IRMAA brackets change annually. The information in this article reflects rules in effect as of May 2026. Medicare.gov is the authoritative source for current premiums, brackets, and enrollment rules. Decisions about Medicare coverage should be made with consideration of your specific health needs and financial situation.
Mayo Clinic benefits content
This article describes Mayo Clinic retirement benefits as we understand them based on publicly available information and our experience working with Mayo Clinic employees and retirees. Plan provisions can change, and your specific benefits depend on your hire date, employment classification, and other factors. Consult Mayo Clinic Human Resources, your plan documents, or a qualified advisor for guidance specific to your situation. The views in this blog are the views of Fortress Financial and not the views of Mayo Clinic. Mayo Clinic and Fortress Financial Group are not affiliated.
Forward-looking content
Statements about future market behavior, economic conditions, or planning outcomes are forward-looking and subject to numerous risks and uncertainties. Actual results may differ materially. Use forward-looking statements as one input among many, not as a basis for specific decisions.
