When it comes to making decisions about whether or not to convert pretax IRA or 401(k) savings to Roth — paying the tax now or waiting until later — a lot of people get caught up in the math.

They turn to financial-planning software, either through professional planners or via one of the few programs available to do-it-yourselfers with subscriptions, like Boldin or ProjectionLab. The Roth conversion calculators in these financial-planning programs are designed to model and quantify the analysis to tell you whether you will end up paying more tax now or more tax later.

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“It’s going to be wrong,” said Andy Panko, a certified financial planner and educator who blogs, podcasts and runs a popular Facebook group through his platform Retirement Planning Education.

This is the surprising message Panko recently gave to a group of advisers gathered for a professional conference as he walked them through the latest strategies for helping clients figure out retirement income strategies. Roth conversions are a huge topic among retirees facing required minimum distributions at age 73, but they may be too hot a topic. “It’s the industry’s fault for being too vocal, for beating the drum on Roth conversions. Consumers are just bombarded with conversion, conversion, conversion,” Panko said. “Doing a Roth conversion won’t magically make your plan work, so don’t lose sleep on it.”

The problem with calculations projecting the value of Roth conversions is that they rely a lot of assumptions, like future tax rates, inflation and portfolio growth. They even delve into the order and timing of the deaths of the clients, which is particularly tricky when it involves a married couple.

For the bottom line, you usually get a number that is the estimated tax difference between converting and not converting. It might say something like, if you convert a $1 million IRA or 401(k) in $100,000 increments over 10 years, you’ll end up saving $400,000 in taxes over a long span of time. Or you may find that not converting saves you a similar amount of money by continuing to defer taxes (but ends up hitting your heirs when they have to convert the balance they inherit within the 10 years after your death).

Whatever that number is, it’s based on too many assumptions to be actionable, Panko said.

“It does provide some context and provide some directionality, or a sense of magnitude,” he added. “But do not rely on software using 30-year projections that says it will save you some amount of dollars over time. Don’t rely on it too blindly and speak of these reports as certainty or fact.”

Panko told the advisers to instead look at this as “directionality” to be considered: Solve first for the known factors and don’t try to get specific with the future unknowns. “It’s human nature to try to solve the unsolvable and be as precise as possible, but we also can’t kid ourselves that we know the answers,” he said.

The Roth conversion question starts with whether paying the tax now seems to be in your favor or not. It’s what Panko called an “optimization technique,” not the be-all and end-all of a retirement plan. “Whether a client does conversions or not is not going to make or break the feasibility of their financial plan,” he said.

To suss this out, you need to get specific about what you are trying to do today. Are you thinking about required minimum distributions and worried they will be too large? Panko has a client with an impending RMD that will be $280,000, and they will have to pay tax on that as income. Are you concerned about the tax burden on the surviving spouse if the other spouse dies? Is your main consideration paying the tax in advance for your heirs?

Sometimes, not doing a Roth conversion is the right answer.

For example, if you’re 60 and have $300,000, you’ll likely spend through the whole account by the end of your life without having to think about conversions. At the other end of the spectrum, Panko had a client recently who was going to be in the 37% tax bracket his entire life whether he converted his $7 million IRA to Roth or not. So it did not make sense at face value for him to bother converting.

For those in the middle, even if you decide a conversion is generally in your best interest, you have to plan year by year and determine an amount. “Conversions likely make sense or don’t make sense,” Panko said. “If it’s likely, then do some. Exactly how much? It’s hard to say.” That’s why the software uses so many assumptions.

You can stick with the specifics that you can figure out. Panko suggested some questions that clients, and their advisers if they have them, should ask. Do they want to stay:

Once you know your answers to these questions, you can back into your actual budget for a Roth conversion. But don’t act too fast. The final pro tip from Panko is to wait until as close to the end of the year as possible to make a final determination, since at that time you’ll know the rest of your income picture for tax purposes.

Got a question about investing, how it fits into your overall financial plan and what strategies can help you make the most out of your money? You can write to me at . Please put “Fix My Portfolio” in the subject line.

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