Roth Conversion Explained: When It Makes Sense and How to Do It

A roth conversion moves money from a pretax account, usually a traditional IRA or an old 401k you rolled into an IRA, into a Roth IRA, and you pay ordinary income tax on every dollar you move in the year you move it. That is the whole deal. You are choosing to pay tax now so the money grows tax free and comes out tax free later, instead of deferring the tax and paying it on every withdrawal in retirement. Nothing leaves the retirement system. The dollars just change tax character, from money that is taxed later to money that is taxed now and then never again. The IRS lays out the mechanics in Publication 590-A, which covers contributions and conversions into IRAs, and the overview of the destination account lives on the IRS Roth IRAs page. People hear the word conversion and picture something exotic. It is not. It is a transfer between two retirement accounts that happens to trigger a tax bill. Once you have a roth conversion explained this way, the rest of the planning is just arithmetic about rates and timing.

Here is how it runs through your return. Say you convert 50,000 dollars from a traditional IRA in 2026. That 50,000 lands on your Form 1040 as ordinary income, stacked on top of your wages and everything else you earned that year. If your marginal rate is 24 percent, the conversion costs roughly 12,000 dollars in federal tax. The custodian sends you a Form 1099-R coded for the conversion, and you report the taxable amount on Form 8606, the form that also tracks any after-tax basis you carry from year to year. There is no 10 percent early withdrawal penalty on the conversion itself, even if you are under 59 and a half, as long as the money goes straight into the Roth and you do not pull it back out too soon. That last clause matters, and it trips people up, which I get into below. The conversion is not a withdrawal you spend. It is a relocation of retirement money, and the tax is the toll you pay to cross from the pretax side to the Roth side.

Why would anyone volunteer to pay tax sooner? Because of where rates are likely to sit when you finally tap the money. If you believe your retirement tax rate will be the same or higher than today, paying tax now at a known rate beats paying an unknown, possibly higher rate later on a much larger balance. A Roth also has no required minimum distributions during your lifetime, so the money can keep compounding untouched, and it passes to heirs income tax free. Those features are why high earners and early retirees lean on conversions so heavily. The tax-free growth runway is longer the earlier you convert, so a 40-year-old who converts and lets the Roth ride for 25 years captures decades of untaxed compounding, while a 70-year-old gets a shorter runway and has to weigh the upfront tax more carefully against the time the money has left to grow.

The mistake we see every year is people paying the conversion tax out of the IRA itself. Do not do that. If you convert 50,000 and have the custodian withhold 12,000 for taxes, only 38,000 actually reaches the Roth, and if you are under 59 and a half that withheld 12,000 counts as an early distribution subject to the 10 percent penalty. Pay the tax from a taxable account, a savings or brokerage account outside the IRA, so the full amount converts and keeps compounding tax free. One edge case worth flagging. A conversion is not the same as a contribution, and it does not count against your annual 7,500 dollar IRA contribution limit, 8,000 dollars if you are 50 or older. You can convert a million dollars in a year if you want and still make a separate regular contribution. If you want us to model the tax hit before you pull the trigger, start at our tax strategy consulting page or reach out through our new client inquiry form.

Every pretax dollar you convert is taxed as ordinary income in the year the conversion happens, full stop. It is not capital gains, there is no preferential rate, and it stacks on top of your other income, which is what makes the timing matter so much. The amount you convert can push part of your income into a higher bracket, so a clean conversion plan looks at where the top of your current bracket sits and fills it up without spilling over. The taxable portion flows onto your Form 1040 and gets reported on Form 8606, and the IRS describes the income treatment of these distributions and conversions in Publication 590-B. The contribution side and the conversion ordering are covered in Publication 590-A. Read those two together and you have the federal picture.

Run the numbers on a married couple filing jointly in 2026. Their standard deduction is 32,200 dollars. Suppose their taxable income before any conversion is 150,000 dollars, which leaves them comfortably inside the 22 percent bracket. The top of that bracket for joint filers sits well above their income, so they have room to convert a chunk and still stay at 22 percent. If they convert 40,000 dollars, that whole amount gets taxed at 22 percent, about 8,800 dollars, assuming it does not cross into the next bracket. Convert too much and the overflow gets taxed at 24 percent, then 32 percent, and the marginal cost climbs fast. That is the core discipline of conversion planning. You convert to the top of a bracket, not past it. The bracket you target is a choice, not an accident, and it should reflect what you expect rates to look like for you in retirement.

The trap people fall into is forgetting that conversion income ripples into other parts of the return. It raises your adjusted gross income, which can shrink credits, trigger the 3.8 percent net investment income tax on your other investment income, and bump up how much of your Social Security is taxable if you are already collecting. A conversion can also reduce or wipe out income-based deductions and phase-ins you were counting on. We also see people convert in December without checking their estimated taxes, then eat an underpayment penalty in April because the withholding never matched the new income. If you convert late in the year, you may need a fourth quarter estimated payment or extra withholding to stay clean, and there are timing tricks with withholding that can cure an underpayment if you plan for them in advance rather than discovering the gap at filing time.

There is also the question of how much basis, if any, rides along with the conversion. If you have ever made nondeductible contributions, part of what you convert is after-tax money you already paid tax on, and that part is not taxed again. Form 8606 is where you prove it. Skip the form and the IRS will happily tax the whole conversion a second time, because the burden is on you to document your basis. We see returns every season where prior preparers never filed the 8606, and the client has been losing the tax-free portion of conversions for years without realizing it.

The edge case to know. State tax applies too. New York taxes conversion income as regular income, so a New York City resident is layering city and state tax on top of the federal hit, which can add another ten points or so to the effective cost of converting. That changes the calculus on whether to convert now or wait until you have moved to a lower-tax or no-tax state in retirement. We coordinate the federal, state, and city pieces when we prepare individual tax returns, and we pressure test the bracket math through tax strategy consulting before you convert. You can get that started through our new client inquiry page. One more practical point on timing within the year. Because the tax attaches to the year of the conversion, a conversion done on December 31 and one done on January 1 fall in different tax years, which lets you split a large planned amount across two years and two sets of brackets with only a single day between them.

The pro-rata rule says you cannot cherry-pick only your after-tax dollars to convert. The IRS makes you treat all your traditional, SEP, and SIMPLE IRAs as one big pooled account, and any conversion comes out proportionally pretax and after-tax based on the whole pool. This is the single most misunderstood piece of conversion mechanics, and it wrecks a lot of backdoor Roth attempts. The calculation lives on Form 8606, and the rules are spelled out in Publication 590-A. The thing to burn into memory is that the IRS does not see your separate accounts the way you do. To you, the nondeductible IRA at one custodian and the rollover IRA at another are two different buckets. To the formula, they are one pool, and every conversion dollar draws proportionally from pretax and after-tax money in that pool.

Walk through a real example. You have 7,000 dollars of after-tax basis sitting in a nondeductible traditional IRA, and you also have 63,000 dollars of pretax money in a rollover IRA from an old job. Total pool, 70,000 dollars, of which 10 percent is after-tax basis. You convert 7,000 dollars hoping it is all tax free because it was your nondeductible contribution. It does not work that way. Because 90 percent of your total IRA money is pretax, 90 percent of your 7,000 dollar conversion, or 6,300 dollars, is taxable, and only 700 dollars comes out tax free. The remaining basis stays trapped and prorates across every future conversion until the pretax money is gone. You report all of this on Form 8606, which tracks your basis year over year, and the IRS reference for how distributions carry basis is Publication 590-B. People expect a tiny tax bill on that conversion and instead get taxed on almost the whole thing, which is a brutal surprise at filing time.

The fix we recommend constantly. If your employer plan accepts incoming rollovers, roll your pretax IRA money into your current 401k before December 31 of the conversion year. Pretax dollars sitting inside a 401k are not part of the IRA pool for the pro-rata calculation, which the IRS measures on December 31. Empty out the pretax IRA into the 401k, leave only the nondeductible basis behind, and now your conversion is nearly all tax free. This single move is what makes a clean backdoor Roth possible for high earners who already have pretax IRA money lying around. The order of operations is the whole game. Roll the pretax money out first, confirm the IRA holds only basis, then convert.

The common mistake is doing this in the wrong order or in the wrong year. The snapshot is your total IRA balance on December 31, not the day you convert, so a rollover that lands on January 2 does not help that year. We also see people forget that a SEP IRA or SIMPLE IRA they opened for a side business counts in the pool. Self-employed clients are especially prone to this, because they set up a SEP, stuff it with deductible contributions, and then wonder why their backdoor Roth got taxed. If it is a traditional, SEP, or SIMPLE IRA in your name, it is in the pool. The edge case worth knowing. A spouse’s IRAs are not pooled with yours. Pro-rata is per person, so the rule looks at your IRAs only, which means a couple can sometimes run the backdoor for one spouse cleanly while the other spouse untangles a pretax balance first. Another edge case. Inherited IRAs you hold as a beneficiary generally sit outside the pro-rata pool for your own conversions, though you cannot convert an inherited IRA itself unless you are a surviving spouse who has treated it as your own. And the December 31 measurement means a poorly timed rollover can quietly ruin an otherwise clean year, so we confirm the pretax balance is actually at zero before signing off on the conversion. This gets technical fast, and a clean backdoor Roth depends on getting every step right. We map it out as part of investment coordination and through tax strategy consulting, and you can bring us your statements through the new client inquiry form.

There are two separate five-year clocks, people constantly confuse them, and recharacterization of a conversion is dead. Take the recharacterization point first because it changes how you should plan. Before 2018 you could convert, watch the market drop, and undo the conversion to erase the tax bill. The Tax Cuts and Jobs Act killed that for conversions. Once you convert, it is permanent, you owe the tax, and there is no rewind button. The IRS confirms conversions cannot be recharacterized on its Roth IRAs page. That is exactly why you never convert more than you can comfortably pay tax on, because you cannot take it back. Note the narrow exception that still exists. You can still recharacterize a regular annual contribution, say moving a Roth contribution to a traditional one before the deadline, but a conversion is locked the moment you do it.

Now the two clocks. The first five-year rule governs whether your earnings come out tax free. For a Roth to produce qualified, fully tax free distributions of earnings, you need to be at least 59 and a half and have had any Roth IRA open for at least five years. That clock starts January 1 of the year of your first Roth contribution or conversion and never resets, so once you clear it you are done forever, no matter how many new Roth accounts you open later. The second five-year rule is conversion specific and exists to stop people from using a conversion to dodge the early withdrawal penalty. Each conversion has its own five-year clock, and if you are under 59 and a half and pull out converted principal before its clock runs, you owe the 10 percent penalty on it even though you already paid income tax at conversion. Publication 590-B at the IRS distributions guide walks through the ordering rules, and the contribution side is in Publication 590-A.

Here is the example that makes it click. You convert 50,000 dollars at age 52. You already paid income tax on it. If you withdraw that 50,000 at age 55, only three years later, you owe a 5,000 dollar penalty, 10 percent, because the conversion’s own five-year clock has not finished and you are under 59 and a half. Wait until age 57, past the five years, and the penalty is gone. Each conversion you do has its own clock, so a conversion in 2026 and another in 2027 are tracked separately, oldest first. The mistake we see. Clients assume they paid the tax, so the money is theirs to take whenever. The income tax and the penalty are two different gates, and clearing one does not clear the other.

The reason these clocks rarely bite the people they are designed for is the ordering rule. Roth distributions come out in a fixed sequence, your direct contributions first, then your conversions oldest to newest, then earnings last. Contributions can always come out tax and penalty free, so most people who need cash are pulling from the contribution layer and never touch a conversion clock at all. The clocks only matter when you start dipping into converted principal early or into earnings before you are qualified. The edge case worth flagging. Once you turn 59 and a half, the conversion five-year clock stops mattering entirely for the penalty, because the early withdrawal penalty itself disappears at that age. So the conversion clock is really a young-saver problem, not a retiree problem. Another edge case. The death or disability of the account owner can also lift the penalty regardless of the clock, as do several other statutory exceptions such as certain medical and first-home situations, so the 10 percent is far from automatic even inside the five-year window. The point is that the two clocks and the exceptions interact, and a withdrawal that looks penalized on paper sometimes is not once you apply the right exception. Coordinating conversions with your actual withdrawal timeline so you never trip a clock you did not see coming is core to investment coordination and to building a sane multiyear plan through tax strategy consulting. Bring us the account statements through our new client inquiry form.

A conversion makes sense when you can pay the tax at a lower rate today than you expect to pay on that money in retirement. That is the entire question. Everything else is detail. The strongest candidates are low-income years, a market dip that lets you convert more shares for the same tax, and the long stretch between retiring and starting required minimum distributions or Social Security when your taxable income often bottoms out. The IRS overview of how these accounts work sits on its Roth IRAs page, and the contribution and conversion mechanics are in Publication 590-A, with the distribution side in Publication 590-B. If your answer to the rate question is that retirement looks lower than today, you probably should not convert much. If it looks higher, or even just the same, converting now starts to pay off.

Low-income years are the prize. Say you retire at 62 with no wages, you are not yet taking Social Security, and your taxable income for a couple of years is near zero. With the 2026 married filing jointly standard deduction at 32,200 dollars, you can convert that much and pay nothing, then convert more to fill the 10 and 12 percent brackets cheaply. A retiree who converts 60,000 dollars a year for five years during that low window can move 300,000 dollars into a Roth at single-digit and low-double-digit rates, money that would otherwise come out at 22 or 24 percent once Social Security and required minimum distributions stack on at 73. That window between retirement and age 73 is the sweet spot, and the people who plan for it years ahead capture far more than the people who wake up at 72 and try to cram it all into one year. A market dip is the other moment. If your IRA drops 20 percent, converting the same number of shares costs 20 percent less tax, and the rebound happens inside the Roth tax free. We see people freeze during downturns. That is precisely when conversion math is best, because you are moving depressed shares and paying tax on the lower value.

Now the brakes, because conversions are not free and the cliffs are real. Two adjusted gross income driven traps catch people. The first is IRMAA, the income-related surcharge on Medicare Part B and Part D premiums. A conversion that spikes your AGI today raises your Medicare premiums two years later, since IRMAA looks back at your return from two years prior, so a big one-year conversion can cost thousands in surcharges down the line and the increase applies per person on a married couple. Spreading conversions over several years keeps you under the IRMAA thresholds. The second is bracket bumping plus the Social Security taxation and net investment income tax effects we covered earlier. A lump conversion can simultaneously push you into a higher bracket, make more of your Social Security taxable, expose your investment income to the 3.8 percent surtax, and raise your Medicare premiums two years out. That is four separate costs stacking on one decision.

The mistake. People convert one giant lump and trigger every cliff at once. Smaller annual conversions, sized to bracket and IRMAA thresholds, almost always beat one big year. The backdoor Roth, a nondeductible contribution converted right away, is the move for high earners locked out of direct Roth contributions, but only if you have cleared the pro-rata trap first by getting pretax IRA money into a 401k. The edge case worth weighing. If you expect to leave this money to heirs, a conversion can be a gift to them, because they inherit a Roth that comes out income tax free rather than a traditional IRA they must drain within ten years and pay tax on at their own rates, possibly during their peak earning years. This is judgment work, not a formula, and the right answer depends on your bracket today, your bracket later, your state, your Medicare status, and your estate goals. We build multiyear conversion ladders through tax strategy consulting and coordinate the account mechanics through investment coordination. Start at our new client inquiry page.