I’m doing Roth conversions, but my IRA balance keeps going up. When do I stop?

Beth Pinsker| MarketWatch | July 18th, 2025

Retirement blogger Fritz Gilbert is trying to reduce his future tax burden, but it’s surprisingly harder than he thought.

With Roth conversions, you are trying to empty your bucket while it’s constantly being refilled.

Fritz Gilbert was taking a break from his popular retirement blog, “The Retirement Manifesto,” but came back recently to discuss an issue that was vexing him: No matter how aggressive he thought he was with Roth conversions over the past several years, his balance kept going up. It was a little bit like the opposite-world version of the nursery rhyme “There’s a hole in the bucket.” He keeps taking money out, but the bucket is still full.

The way Roth conversions work is that you take money out of a pretax retirement account like an IRA or a 401(k), pay the tax and then transfer the money to a Roth IRA where the money will grow tax-free into the future. The impetus for doing this is if you think you have a lower tax rate today than you (or your inheritors) will have in the future. In Gilbert’s case, he is trying to reduce the large balance in his IRAs to reduce the burden on his wife in the event of his death. If she’s suddenly filing as a single person, but has to draw required minimum distributions from both of their accounts combined, the tax hit could be significant.

The question then becomes: If you can’t really get to zero in your pretax accounts with Roth conversions, when should you stop?

One guardrail is age, said Sam Huszczo, a certified financial planner and chartered financial analyst based in Detroit. The sweet spot for Roth conversions is the time between when you stop work and when you start having to take required minimum distributions from pretax accounts at the same time as Social Security. For today’s retirees, that would be at age 73, after 2033 it will be 75, unless rules change further.

“We estimate what tax bracket you will be in once RMDs kick in with Social Security, and then compare it to your tax bracket today,” Huszczo said.

When to stop Roth conversions

If you’re going along doing Roth conversions, as Gilbert is, you’ll know when to stop when the tax-rate arbitrage flips. Before you withdraw money each year, or at whatever interval you chose, you need to do that same analysis Huszczo suggested. If the money is intended to eventually pass to heirs, at some point you want to also consider your tax rate vs. theirs. 

“In terms of tax efficiency, it needs to be based on tax brackets,” Huszczo said. “But it should all be customized advice. The math gets tighter as you go along and there’s more opportunity to make a bad decision.”