Roth Conversions Explained: When They Make Sense

Bill retired at 61 with $1.2 million and a tax bill of almost nothing.

For ten years he lived off a savings account, reported barely any income, and told everyone at church he had beaten the IRS.

Then he turned 73. The required withdrawals started. His wife died the following spring, which moved him into single tax brackets that are half as wide. And his Medicare premium went up, because of a tax return he had filed two years earlier and forgotten about.

Bill did not beat the IRS. He scheduled an appointment with it, twelve years out, and then forgot he had made it.

Here is the thing that would have fixed it, and it fits in one sentence.

You pay tax on money now, so you never pay tax on it again.

That is a Roth conversion. Everything else in this article is just working out whether that trade is good for you, and the answer comes down to one comparison: is the rate you pay today lower than the rate you would have paid later?

If yes, convert. If no, do not. If you have no idea, you are in the same position as almost everyone, and that is what the next 3,000 words are for.

You move money from a traditional IRA or 401(k) into a Roth account. The amount moved becomes taxable income in that year. After that, it grows tax free and qualified withdrawals come out tax free.

The IRS covers the mechanics on its Roth IRA page, with the detailed distribution rules in Publication 590-B.

Two features matter more than the headline tax saving.

No required minimum distributions for the owner. A traditional IRA eventually forces money out on a schedule set by the IRS, using the life expectancy tables on its required minimum distribution page. A Roth IRA never does that to you. That means you control your reported income for life, which turns out to be worth a great deal.

One thing you should know up front: conversions cannot be undone. The ability to reverse one, once called recharacterization, was eliminated for conversions. Once you convert, that is the decision.

Strip away the noise and it is one question.

That looks simple and then people get stuck, because predicting your future rate feels impossible.

It is not impossible. It is arithmetic, and it usually goes the same direction.

Here is why your future rate is frequently higher than people expect:

The widow's penalty in particular is the reason conversions are far more valuable for married couples than most calculators suggest. We took that apart in the widow's penalty explainer, and it is the single most underrated argument for converting.

There is a specific stretch of years where conversions are cheap, and most people sleep through it.

The second row is the opportunity. No wages. No Social Security yet. No forced distributions. Your taxable income is whatever you decide it is, which happens exactly once in a life.

Retire at 62 and you might have ten or eleven of those years. Spend them living quietly off a savings account and reporting almost no income, and you have not saved on taxes. You have wasted a decade of cheap tax brackets and handed the bill to your seventies.

A couple retires at 62 with $900,000 in traditional IRAs and modest other savings. They can live on about $70,000.

The couple on the right paid more tax in their sixties and much less for the following twenty five years. On a portfolio this size the lifetime difference commonly lands in the six figures.

And notice the last two rows, which no simple calculator captures. They also bought themselves a dial: the ability to spend from the Roth in any year when adding income would be expensive.

This is the detail that decides whether a conversion works, and it has nothing to do with tax rates.

Pay the conversion tax with outside money, not with the converted money.

Converting $50,000 and withholding the tax means only $39,000 actually reaches the Roth. You paid full price and received 78% of the product.

So the practical rule is blunt: if you do not have cash outside the retirement account to pay the tax, the conversion is usually weaker than it looks. That single constraint disqualifies more people than any bracket math.

Here is where people get genuinely confused, because there are two separate five year clocks and they do different jobs.

Two practical takeaways.

If you have never had a Roth IRA, open one now. Even a small contribution starts clock one. It costs almost nothing and it means the clock is already old when you need it.

If you are under 59 and a half, plan around clock two. Converting money you intend to spend within five years can create a penalty. The full ordering rules are laid out in Publication 590-B, and this is one of the few places where reading the actual IRS text beats reading a summary.

If you have ever made a nondeductible contribution to a traditional IRA, you have basis, and basis does not come out first.

The IRS treats all your traditional, SEP and SIMPLE IRAs as one pot when calculating how much of a conversion is taxable. You cannot convert only the after tax portion.

This is tracked on Form 8606, and if you have ever made a nondeductible contribution and never filed that form, this is your reminder to go find out.

There is a well known workaround: money in a 401(k) is not part of that calculation. Rolling a pretax IRA into an employer plan, where the plan accepts it, can empty the pot and make conversions cleaner. That is the reverse of the usual rollover advice, and it is one of the reasons the rollover decision is not as obvious as it looks. We covered that trade-off in the 401(k) rollover guide.

A conversion is income, and income has consequences beyond your tax bracket.

The Medicare one is the most common surprise. Premiums are based on a two year lookback, and the thresholds are cliffs rather than gradual phase-ins, so a single dollar over a line can cost a couple thousands for the year. The CMS and Medicare rules are summarized on the Medicare costs page. We wrote the full version of this trap in Roth conversions and IRMAA.

The ACA one is the most underestimated. For someone retired before 65 and buying coverage on the marketplace, every extra dollar of conversion income reduces the premium credit. In the phase-out range, the combined effect of income tax plus lost subsidy can exceed 30% even when the stated bracket is 12%. That is why most early retirees do very small conversions before 65 and save the aggressive converting for after Medicare starts.

The technique has no glamorous name. It is filling a bracket, deliberately, once a year.

Step one says November for a reason. Convert in January and you are guessing about a year that has not happened. Convert in December and you already know your dividends, your capital gains distributions and your actual spending.

Step six exists because of things you do not control. A mutual fund can declare a large capital gains distribution in the third week of December and push you over a line you carefully measured in October.

And step four matters enormously for one reason people miss: the tax year you turn 63 is the first year that feeds your Medicare premiums. Before that, conversions are invisible to Medicare. That makes your very early sixties the most valuable conversion years of all.

Two rows deserve a note.

The charity row. If a traditional IRA is going to a qualified charity at death, converting is actively wasteful. The charity pays no tax on it either way, so you would be paying tax voluntarily for no benefit. The same logic applies to qualified charitable distributions during life, which let you move IRA money to charity without it ever appearing in your income.

The market drop row. Converting after a decline moves more shares for the same tax bill, and the entire recovery then happens inside the Roth, tax free. It requires doing the emotionally hardest thing at the worst moment, which is why almost nobody does it.

Same tax bill, roughly 43% more tax free money at the end. This is one of the few genuinely free lunches available to an ordinary investor, and it is available only during the exact weeks people least want to think about their accounts.

Rules changed in recent years and most retirees have not updated their thinking.

Most non-spouse beneficiaries must now empty an inherited retirement account within ten years rather than stretching it across a lifetime. That compresses the tax into a decade, and often that decade is the heir's peak earning years.

A quarter of a million dollars of difference, decided by which container the money happened to sit in.

So the honest framing is that a conversion is partly a gift. You are volunteering to pay tax at your rate so your heirs never pay at theirs. Whether that appeals to you is a values question, not a math question, and it is worth being explicit about it rather than letting a spreadsheet decide.

There is a step people skip entirely, and it often beats converting.

If you have room in a low bracket and you also need money to live on, you do not have to convert. You can just withdraw from the traditional IRA and spend it, leaving your taxable account alone.

Both approaches drain the traditional IRA at low rates, which is the actual goal. Converting adds the tax free growth benefit but requires outside money for the tax. Spending directly from the IRA is simpler and still accomplishes the main objective.

A lot of people conclude they cannot do Roth conversions and therefore do nothing. That is the wrong conclusion. If you cannot convert, withdraw and spend instead. The enemy is a decade of reporting almost no income while the pretax balance compounds.

Once you reach the qualifying age, a qualified charitable distribution lets you send money straight from an IRA to a qualifying charity, and the amount is excluded from your income entirely. Not deducted. Excluded.

For a charitably inclined retiree sitting near an income threshold, this does four useful things in one transaction. The eligibility age, annual limits and interaction with deductible IRA contributions all have specifics worth confirming on the IRS's distribution guidance before executing.

And it changes the conversion math. Money earmarked for charity should generally be the last money you ever convert, because it can leave the account tax free anyway.

Here is what a real sequence looks like for a couple retiring at 61.

Nothing exotic there. No products, no trusts, no insurance. Just arithmetic done once a year in November instead of never.

The decision about when to start Social Security interacts with all of this, because claiming early fills your bracket with income you cannot switch off and closes the conversion window years early. Delaying is as much a tax strategy as a longevity strategy.

Converting in January. You are guessing at a year that has not happened.

Withholding the tax from the conversion. Shrinks the Roth and can trigger a penalty under 59 and a half.

Converting one huge amount. Pushes you into higher brackets and Medicare tiers instead of spreading across years.

Forgetting Form 8606. If you have basis and never filed it, you may pay tax twice on the same dollars.

Ignoring the state. Converting before moving from a high tax state to a no tax state can be an expensive sequencing error.

Converting while on an ACA plan without modeling the subsidy. The lost credit can exceed the benefit.

Doing nothing at all. The most expensive mistake on this list. A decade of unused low brackets is a real, permanent loss that simply never shows up as a line item anywhere.

A Roth conversion is a rate arbitrage with three extra features attached: no forced withdrawals for you, control over your reported income for life, and a cleaner inheritance.

The decision framework is short enough to memorize:

Sit down in November with last year's tax return and this year's account balances. Find the top of your bracket. Subtract what you already have coming. Whatever is left is your conversion room, and it expires on December 31.

See you next issue. 🪙

This is general education, not financial or tax advice. Tax brackets, income thresholds, Medicare premium tiers, RMD ages, contribution limits, five year rule mechanics and beneficiary distribution rules are set by federal law, change over time, and depend entirely on individual circumstances. State income tax treatment varies and can change the answer completely. All dollar figures and rate examples here are simplified illustrations, not projections. Roth conversions are irreversible. Consult a licensed tax professional before converting any amount.

Sources: IRS guidance on Roth IRAs, Publication 590-B on distributions from individual retirement arrangements, Form 8606 for nondeductible contributions, and required minimum distribution rules; Medicare.gov information on Medicare costs and income related premium adjustments.Here is the entire concept, and it fits in one sentence.