For most retirees, the number on the IRA statement and the number their family actually keeps start out identical. By the time both spouses have passed and the inheritance has cleared the SECURE Act 10-year window, those two numbers can be hundreds of thousands of dollars apart — sometimes millions. The drift between “statement balance” and “what the family keeps” isn’t caused by markets. It’s caused by four specific decisions inside the household’s Roth conversion approach, and most DIY investors are only aware of one of them.
Consider a typical client pattern our team has worked through many times. Tom is 62, a retired engineer who has tracked the household’s investments in spreadsheets for nearly 30 years. He didn’t panic in 2008. He didn’t chase meme stocks in 2021. He and Linda have built up roughly $1 million in their traditional IRA by doing things the right way over a long stretch. Two years ago, Tom started doing Roth conversions — converting to the top of the 24% tax bracket each year, with his CPA reviewing the math and agreeing. On paper, everything checks out.
After more than 14 years and over 2,400 multi-year conversion plans, our team has watched households just like Tom and Linda’s quietly leave hundreds of thousands of dollars on the table because no one mapped all four conversion decisions together. This article walks through each one using Tom and Linda as the running example, shows how each quietly works against the family, and explains why all four compound rather than simply add.
Decision #1: How You Invest Inside Your IRA (Before You Convert)
The first decision has nothing to do with the conversion itself. That’s exactly why most people miss it.
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Tom managed his own portfolio for 30 years and was better at it than most. But like nearly every self-directed investor — and most professional managers — there was a gap between what the market returned and what Tom actually captured. The gap was the small things: a position sold during a 2008 downturn that took years to climb back into, a few months sitting in cash that turned into longer, a fund that looked great in the brochure and underperformed its benchmark over a decade.
A 1% or 2% annual gap doesn’t stay small. Compounded over thirty years on a growing balance, it produces hundreds of thousands of dollars in foregone wealth. Tom’s IRA reads $1 million today. With a low-cost, behaviorally-disciplined setup, it could plausibly be closer to $2 million.
Fees compound the same way. Tom’s advisor charged close to 2% all-in once fund expense ratios and platform costs were stacked on the advisory fee. The vast majority of active managers fail to outperform their benchmark over a decade — and the ones that do often can’t repeat it for three years in a row. Underperforming funds get quietly closed, which makes the surviving universe look better than reality.
This is the first compounding layer. The conversion math that follows operates on whatever balance reaches conversion year. For more on planning errors that derail conversion strategies broadly, see our team’s analysis of 5 costly Roth conversion mistakes.
Decision #2: How Much You Convert
Tom converts to the top of the 24% bracket every year. The CPA approved. The strategy looks responsible.
The problem is the calculation only considers this year’s bracket. It doesn’t model what happens to the balance Tom leaves behind, or what happens to Linda after Tom is gone.
At Tom’s RMD age — currently 73 for his cohort — the IRS forces taxable income out of the remaining traditional IRA balance on its schedule, not Tom’s. After another decade of growth, that forced income can push Tom into the 32% bracket or higher. IRMAA Medicare surcharges kick in and add thousands of dollars a year for the rest of his life. For more on the IRMAA impact specifically, see our team’s analysis of how Roth IRA conversions impact Medicare premiums.
The piece Tom didn’t see coming: if Tom passes first, Linda files as a single taxpayer. Single-filer brackets and IRMAA thresholds hit at much lower income levels than joint thresholds. The money Tom thought he was protecting by staying in the 24% bracket becomes meaningfully more expensive for Linda. This is the “widow’s trap,” and it lands harder than most families expect.
The “safe” conversion amount, viewed across a lifetime instead of a year, frequently turns out to be the most expensive one. Getting the right number requires modeling RMD trajectory, Social Security timing, IRMAA thresholds, life expectancy, and cash flow together — not one variable at a time on a spreadsheet.
Decision #3: When You Convert
Tom converts every December. Same time of year, same approach. Wait until income is mostly settled, check with the CPA or tax software, execute.
It feels organized. It also ignores the single biggest tactical advantage available to a Roth conversion strategy.
In 2022, the broad market dropped sharply and growth-heavy holdings lost nearly a third of their value. Tom did what most disciplined DIY investors do when things get shaky — he paused. He waited to see if the market would fall further. By the time it became clear the bottom had passed, the recovery was already underway and the depressed valuations were gone.
That pause is what made it the most expensive year. When a holding drops in value and the household converts at the lower price, the conversion tax is calculated on the smaller amount — straight tax savings. But the bigger benefit is the recovery itself: the climb back up happens inside the Roth IRA, tax-free permanently. Tom didn’t just overpay conversion tax in 2022. He gave up tax-free growth he can never get back.
Our team’s research across thousands of conversion plans shows that waiting until December is consistently the least beneficial conversion timing. The optimal moments arrive during the year, often during exactly the kind of volatility that makes most households freeze. For more on capitalizing on volatility, see our team’s analysis of navigating Roth conversions in a volatile market.
Decision #4: Which Assets You Convert First
Tom’s portfolio is a traditional 60% stocks, 40% bonds and cash. When he converts, he moves a proportional slice — if he’s converting $75,000, it breaks down as roughly $45,000 from equities and $30,000 from bonds and cash.
It feels balanced. It feels like exactly what a responsible investor would do. It also gives up most of the tax-free compounding benefit the conversion is supposed to deliver.
The reason: tax-free compounding scales with the underlying growth rate. Bonds growing at 3% to 4% a year inside the Roth still grow tax-free, but the tax-free benefit on a low-growth asset is modest. Growth equities averaging 8% to 10% a year over 20 or 30 years inside the Roth produce enormous tax-free compounding. The order of conversion determines how much tax-free runway the highest-growth holdings actually get.
Growth assets should generally cross into the Roth first. Bonds and cash can convert later — or stay in the traditional IRA, where their slower growth doesn’t carry the same future tax cost.
This decision also connects directly to Decision #3. A household that has converted growth assets first ends up holding more cash inside the Roth and more equities inside the traditional IRA over time. During a market downturn, that cash inside the Roth becomes immediately deployable into equities at depressed prices — and the entire recovery happens tax-free. Timing and order work together, and that combination is where significant value lives.
The Compounding Effect: How the Four Decisions Magnify Each Other
The most common assumption is that the four decisions add up. They don’t. They compound.
A smaller balance (Decision #1) converted at the wrong amount (Decision #2) at the wrong time (Decision #3) in the wrong order (Decision #4) leaves dramatically more on the table than the sum of those four taken individually. Each layer makes the next layer worse.
| Decision | DIY Default | Optimized Approach |
|---|---|---|
| #1: Investment setup before converting | High fees, behavior drag, underperforming funds | Low all-in cost, disciplined allocation, benchmark-tested management |
| #2: How much to convert each year | Top of current bracket | Multi-year sequence modeling RMDs, IRMAA, survivor brackets, life expectancy |
| #3: When to convert during the year | December | Throughout the year, with deliberate execution during market drawdowns |
| #4: Which assets to convert first | Proportional slice across all holdings | Growth assets first; cash and bonds last (or never) |
The dollar cost of those four compounding decisions never shows up on Tom’s quarterly statement. It shows up on Linda’s tax return after Tom is gone, when she files single. It shows up in the heirs’ inherited IRA tax exposure when the 10-year window arrives during their highest-earning years. For more on the size of those compounded differences in real plans, see our team’s analysis of strategic Roth conversions that save over $1 million in taxes.
Why Your CPA Won’t Flag This Gap
A reasonable response at this point is: if all of this were true, my CPA would have brought it up.
Most CPAs are excellent at what they’re trained to do — preparing accurate returns and minimizing the household’s tax bill for the current filing year. That work matters. It keeps the household compliant and captures real annual savings.
It is also a different question than how do we minimize the household’s lifetime tax bill? The strategies that look most responsible on this year’s return — staying under the next bracket, avoiding IRMAA spikes, deferring income — frequently increase the household’s lifetime tax bill. The single-year frame and the lifetime frame produce opposite conclusions on many of the same questions.
This is not a CPA failing. It is a scope difference. The lifetime question requires a different toolkit, a different time horizon, and a different planning specialty.
Common Mistakes to Avoid
Several errors quietly compound the cost of an under-optimized DIY approach:
- Treating the investing layer as separate from the conversion plan. It is the foundation the conversion math operates on.
- Stopping at the top of the current tax bracket by default. The most expensive default among IRA Millionaires.
- Converting on a December schedule. Misses the years when market timing creates the largest opportunities.
- Converting proportionally across all holdings. Leaves the largest tax-free compounding benefit unrealized.
- Treating conversions as a one-time decision. Most optimized plans run four to ten years and recalibrate annually against current income, balances, and tax-law context. For more, see our team’s analysis of multi-year Roth conversion strategies.
About Q3 Advisors
Q3 Advisors is a flat-fee fiduciary firm specializing in tax-efficient retirement planning for high-income professionals and retirees. As practitioners of Rothology® — the science of Roth conversion optimization — our team brings the multi-year modeling, market-aware execution, and asset-sequencing discipline that DIY approaches and single-year tax preparation aren’t designed to provide. We don’t sell financial products and we don’t manage investment accounts — we sit on top of what households already have and help them make accountable, fully-coordinated decisions across all four conversion layers. With over $10 billion in projected tax avoidance for our clients over more than 14 years, we have the track record to guide your strategy.
Frequently Asked Questions
What’s the biggest mistake DIY Roth converters make?
Treating the conversion as a one-decision question — “how much do I convert?” — when it’s actually four decisions. The investing setup before any conversion happens, the amount converted each year, the timing within the year, and the order in which assets get converted all interact. Optimizing any one of them in isolation leaves most of the lifetime value on the table.
Can I just keep converting to the top of my current tax bracket?
For households with modest IRA balances, sometimes yes. For IRA Millionaire households, the math frequently says otherwise. Future RMDs sit in much higher brackets for decades, the surviving spouse files single, and the heirs inherit at their highest-earning years. The “safe” current-bracket cap often produces the highest lifetime tax bill.
Why does the timing within the year matter so much?
Because the conversion tax is calculated on the value at the moment of conversion. A market decline of 15% to 30% means the same shares can be converted at a smaller dollar value — straight tax savings. More importantly, the eventual recovery happens inside the Roth IRA tax-free. A December-only conversion habit gives up that opportunity every year except the rare years when December itself happens to be the bottom of a decline.
Why convert growth assets before bonds and cash?
Tax-free compounding scales with the underlying growth rate. A bond yielding 4% inside a Roth still grows tax-free, but the benefit is modest. A growth equity averaging 9% over 25 years inside a Roth produces enormous tax-free compounding. The conversion order determines how much tax-free runway the highest-growth holdings actually get.
What is the “widow’s trap”?
When a married household leaves a large traditional IRA, the surviving spouse files as a single taxpayer. Single-filer tax brackets and IRMAA surcharge thresholds hit at much lower income levels than joint-filer thresholds. The same RMD income that landed comfortably in the 24% bracket for a married couple can land in the 32% bracket — plus higher IRMAA — for a surviving single filer.
Is the problem really that bad if my CPA reviews everything?
CPAs typically optimize for the current filing year. That work is correct and important — but it answers a different question than “how do we minimize the household’s lifetime tax bill?” The strategies that look most responsible on a single-year return often increase the lifetime bill for IRA Millionaire households. The two questions need two different planning toolkits.
Plan Your Roth Conversion Strategy Today!
Each of the four conversion decisions can be optimized independently — but the largest gains come from coordinating all four together, across a multi-year plan calibrated to your household’s specific numbers. To find out what your gap actually looks like — and what an integrated plan would do to close it — schedule a consultation with our team and get a multi-year projection built around your numbers.
