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If you've been doing any research on Roth conversions, you've probably seen a lot of spreadsheets, tax bracket charts, and breakeven analyses. And look, that stuff matters. I've done plenty of deep-dive, numbers-heavy content myself, and there's real value in it. But before you ever open a spreadsheet, there's a more fundamental question you need to answer. One that most people skip entirely.

What are you actually trying to solve for?

Not in a vague, "I want to pay less taxes" kind of way. I mean specifically. Because when it comes to Roth conversions and legacy planning, the answer to that question changes everything: your timeline, your strategy, how aggressive you should be, and whether conversions even make sense for your situation at all.

After working with clients who are approaching retirement with significant tax-deferred balances, I've found the clearest way to frame this is with three numbers: Two, One, and Zero. That's it. Once you know which number you're solving for, the rest of the planning process becomes a whole lot clearer.

Let's walk through each one.

First, Why "Legacy Goals" Beat "Goals"

When I sit down with someone who's five to ten years from retirement and they have a large pre-tax IRA or 401(k), the first thing I ask isn't "what are your goals?" That question is too broad. It leads to answers like "I want to be comfortable" or "I want to leave something for my kids," and while those are fine starting points, they don't give us enough to build a strategy around.

Instead, I ask: What is this money ultimately for, and who is it for?

That's what I mean by legacy goals. And the reason it matters so much in the context of Roth conversions is this. You have a window. If you're retiring between 55 and 65, there is a finite period of time where you have the most flexibility to do conversions efficiently. Once Social Security kicks in at 70, once required minimum distributions start, once Medicare IRMAA surcharges become a factor, your flexibility shrinks. The window closes.

So if you're going to do this, you need to know what you're doing it for before that window narrows. That's where the Two, One, Zero framework comes in.

Solving for Two: Optimizing for the Couple

When you're solving for two, you're planning for both spouses over the full arc of retirement. Think about it this way: if you retire at 60 and you plan to live to 90 or 95, that's a 30+ year horizon. The goal here is to minimize the total taxes you pay as a couple over that entire lifetime. Not just this year, not just the next five years, but the whole run.

This is probably the most common starting point for married couples who retire around the same time and are in reasonably similar health. And when you frame it this way, it often justifies being fairly aggressive with conversions in those early retirement years, before Social Security, before RMDs, before the income picture gets crowded.

Think about what that window actually looks like. You retire, your income drops. You're not drawing from Social Security yet. Your IRAs aren't being forced out through RMDs yet. Your taxable income is lower than it will ever be again for a long stretch of time. That is the opportunity. That is the window where you can move money from pre-tax to Roth at a relatively low tax cost.

Once you hit 70, that window starts closing. You can only delay Social Security so long. RMDs have their own schedule. For couples with pension income on top of that, the picture gets even tighter. Solving for two means you recognize that window early and you use it.

Now, this approach also comes with some assumptions. It assumes both spouses live long lives and that those lives end reasonably close together. In reality, that's not always how it plays out. Which brings us to number one.

Solving for One: Planning for the Surviving Spouse

This is where things get really important, and honestly, it's where I think a lot of couples underplan.

You would want to solve for one, meaning you're optimizing primarily for the tax situation of the surviving spouse, if there's a significant age gap between partners, if one spouse has health concerns or a family history that suggests a shorter life expectancy, or if you simply want to be conservative and plan for that possibility.

Here's why this matters so much. When the first spouse passes, the surviving spouse goes from filing jointly to filing as a single taxpayer. That is a massive shift in the tax picture. The tax brackets compress dramatically. A couple that was comfortably in the 22% bracket filing jointly may find the surviving spouse suddenly in the 32% or even 35% bracket, on the same income, just because of filing status.

Add to that the full value of both spouses' Social Security benefits collapsing down to one (the higher of the two), plus RMDs on any remaining pre-tax assets, and you can see how a surviving spouse can end up in a really difficult tax position.

So if you're solving for one, your Roth conversion strategy looks different. You may convert more aggressively, or prioritize converting the accounts that the surviving spouse will inherit. The goal isn't just to minimize taxes for two people over time. The goal is to make sure that one person, in what is already a really hard season of life, isn't also getting crushed by an unexpected tax bill.

This is the kind of planning that can make a real, tangible difference for families, and it often gets overlooked because couples naturally tend to think of themselves as a unit. But thinking ahead about what life looks like for one can be one of the most loving financial decisions you make together.

Solving for Zero: Planning for the Next Generation

Now we get to the one that surprises people most. Solving for zero means you're not primarily optimizing for either spouse during retirement. You're thinking about what happens after you're both gone. You're planning for your heirs.

There are a few different reasons someone might be in this camp.

The first scenario is the one that sounds counterintuitive: you're already in the highest tax bracket, 37%, and you know you're going to stay there. Maybe you have rental income, pension income, Social Security, and RMDs all stacking on top of each other. You're never going to be in a lower bracket. In that case, does it still make sense to do Roth conversions?

Sometimes, yes. Not because of tax arbitrage. If you and your heirs are both in the 37% bracket, there's no rate difference to capture. But there's something else: flexibility and simplicity. If your adult children are also high earners, inheriting a large traditional IRA means they're going to owe federal and state tax on every dollar they pull out, in their highest-earning years. If you've already got plenty of money and you can prepay that tax now, you can leave them a clean, tax-free inheritance that gives them options instead of obligations. It's a gift, plain and simple.

The more common scenario is when there's a rate gap between generations. Say you're in the 24% bracket in retirement. You've got Social Security, maybe some pension income, but you're not actually drawing on your IRA because you don't need to. Your child, on the other hand, is a high-earning professional in the 37% bracket. Every dollar they inherit from your traditional IRA gets hit with their tax rate, not yours.

In that case, doing conversions at your 24% rate and leaving them a Roth IRA, where they can take distributions tax-free, is a genuinely smart move. You're essentially paying 24 cents on the dollar so they don't have to pay 37. That's real money.

The flip side is also worth mentioning, because solving for zero isn't always about aggressive conversions. If you know your heir is in a very low tax bracket, maybe they work for a nonprofit, maybe they're in ministry, maybe they've chosen a simpler life, they may actually be better off inheriting traditional IRA money and pulling it out at their low rate. In that case, you're not in a rush to convert at all.

The point is: when you're solving for zero, the right answer depends entirely on the tax situation of the people who will receive what you leave behind.

Putting the Framework to Work

So now you've got the framework. Two, One, Zero. The question is: where do you start?

Here's how I think about it. Pick your primary goal, whichever of these three is most aligned with what you care about, and let that be your anchor. From there, you start asking the harder questions. Do I have the window to actually execute on this? What does my income timeline look like between now and 70? What's the breakdown of my assets between taxable brokerage, pre-tax IRA, and Roth? What happens when Medicare kicks in and IRMAA becomes a factor?

Those are real, important questions. But they're much easier to answer, and the trade-offs are much easier to evaluate, once you know what you're trying to accomplish.

In a lot of cases, this is genuinely a gray area. It's not a slam dunk either way, and anyone who tells you it's simple probably isn't accounting for all the variables. Tax law can change. Lifespans are unpredictable. Family situations evolve. A good plan has to be flexible enough to adapt.

But here's what I know for sure: the couples and individuals who start this conversation with a clear sense of what they're solving for, Two, One, or Zero, are always better positioned to make good decisions than those who start by picking an arbitrary dollar amount to convert and hoping for the best.

Start Here

If you're in that 50-65 age range with a significant amount of pre-tax money and retirement is somewhere in your five-year horizon, this is the conversation to start having now. Not next year, not when you retire. Now. Because the window where you have the most control and flexibility is the one you're in right now.

So ask yourself the question: Am I solving for Two, One, or Zero?

Answer that first, and then everything else becomes a lot easier to figure out.

Forrest Dutton is a CERTIFIED FINANCIAL PLANNER™ and the owner of Brightworks Financial Planning. This content is for educational purposes only and is not intended as personal financial, tax, or investment advice. Please consult a qualified professional before making decisions based on your individual situation.