Liz Weston

Dear Liz: I thought your readers would benefit from additional knowledge about Roth conversions. I started converting our IRAs to Roth IRAs when my wife and I turned 60 years old. Years later, I realized that our premiums for Medicare Part B and D were higher because our income in those years exceeded $174,000.

Answer: Triggering Medicare’s income-related monthly adjustment amount (IRMAA) is just one of the potential side effects of a later-in-life Roth conversion.

That’s not to say these conversions are a bad idea.

People with substantial amounts in traditional retirement accounts might benefit from transferring some of that money to Roth IRAs, particularly if the required minimum withdrawals that start at age 72 would push them into a higher tax bracket. They may have a window after they retire, when their tax bracket dips, to convert money and pay the tax bill at a lower rate.

Roths also don’t have the required minimum distributions that apply to other retirement accounts, so people have more control over their future tax bills.

Converting too much, however, can push people into higher tax brackets. Many financial advisors suggest their clients convert just enough to “fill out” their current bracket.

For example, the 12% bracket for married people filing jointly was $19,401 to $78,950 in 2019. A couple with income in the $50,000 range might convert $28,000 or so, because a larger conversion would push them into the 22% tax bracket.

But there are other considerations, as you discovered.

People with modified adjusted incomes above certain levels pay IRMAA adjustments that can add $144.60 to $491.60 each month to their Medicare Part B premiums for doctor visits and $12.20 to $76.40 to their monthly Part D drug coverage premiums. Higher income could reduce or eliminate tax breaks that are subject to income phaseouts, and conversions can subject more of your Social Security benefits to taxation.

At the very least, you should consult a tax pro before any Roth conversions to make sure you understand the ramifications. Ideally, you’d also be talking with a fee-only, fiduciary financial planner to make sure conversions, and your retirement plan in general, make sense.