Fidelity Roth Conversion: How to Do It Without Panic

The first time someone suggested I look at a Fidelity Roth conversion, I nodded like I already knew what they meant. Then I got home, opened a browser tab, and closed it about ninety seconds later. The whole thing felt like a scam I would be volunteering for. Pay taxes now on money I was pretty sure I would owe taxes on eventually anyway? Why would any human being sign up for that?

A Fidelity Roth conversion moves money out of your traditional IRA (or an old 401(k) rolled into one) and into a Roth IRA, and you pay ordinary income tax on the amount you convert in the year you do it, in exchange for that money then growing tax-free and coming out tax-free in retirement. That is the whole trade. Everything else is timing, math, and not tripping over the pro-rata rule.

I am not a financial advisor. I am a personal-finance guy who has done a small conversion, panicked briefly at tax time, and lived to write it down. What follows is a plain walkthrough of what the button on Fidelity’s site actually does, when a conversion is worth doing, and the pitfalls that turned “smart move” into “expensive lesson” for people I know. If your situation is unusual, talk to a CPA. If you just want to know what any of this means, keep reading.

Jump to a section

• What a Fidelity Roth conversion actually is
• Why anyone would trade a tax bill for one
• When a Roth conversion pays off (and when it just costs you)
• The downsides nobody puts on the marketing page
• The pro-rata rule, in plain money terms
• The five-year rule (yes, there are two of them)
• How to do a Roth conversion at Fidelity, step by click
• The tax bill: pay it from outside the IRA
• The multi-year game plan (the conversion ladder)
• Where the actual math lives (and what Dave Ramsey says)

What a Fidelity Roth conversion actually is

A Roth conversion is a paperwork move, not a market move. You are not selling anything and buying something new. You are taking money that already sits inside a tax-deferred account (a traditional IRA, or a former employer’s 401(k) that you rolled to Fidelity) and relabeling it as Roth money. In Fidelity’s system, that means the balance leaves one account number and lands in another. Same investments, often. Different tax future.

The trade is simple to say and painful to feel. Traditional IRA money went in pre-tax, so the IRS is still owed its share. When you convert, you pay that share now, at your current ordinary income tax rate. The Roth side then grows forever without another tax bill, and qualified withdrawals in retirement come out clean. If you want the broader context on the pre-tax side of the equation, my rundown on how retirement savings actually get started covers where these buckets came from in the first place.

You do not have to convert your whole traditional IRA. You can convert a slice. You can convert one year and not the next. You cannot, since the 2017 tax law changed the rules, undo a conversion once it is done. That last part is worth taping to your monitor.

Why anyone would trade a tax bill for one

The pitch for a Roth conversion is basically this: you are betting your tax rate today is lower than your tax rate will be when you actually pull the money out. If that bet is right, you win the difference, and it compounds for decades.

The wins that get people to click the button:

• Tax-free growth for as long as the account exists. A Roth IRA never gets taxed again once the conversion tax is paid. Twenty years of compounding lands in your lap without a partner in it.
• No required minimum distributions. Traditional IRAs force you to start taking money out around age 73 whether you want to or not. Roth IRAs do not. Your money stays yours to leave alone, spend, or pass on.
• A tax hedge on the future. Nobody knows what income tax rates will look like in 2045. Splitting your retirement between pre-tax and Roth is the same idea as owning bonds and stocks. You are not betting on one outcome.
• A gift to your heirs. Inherited traditional IRAs land on someone else’s tax return as ordinary income, usually inside a ten-year cleanout window. Inherited Roth IRAs mostly land as a tax-free gift.

None of these upsides matter if your current tax rate is already high and your retirement rate will clearly be lower. In that case, keep the traditional and take the deduction. A conversion is a tool, not a virtue.

When a Roth conversion pays off (and when it just costs you)

Timing is the whole game with this move. The same conversion done in the right year is a great decision, and done in the wrong year is a self-inflicted wound. Here is the shortlist of years to consider.

A low-income year. A gap between jobs, a sabbatical, an early-retirement window before Social Security kicks in, a year on a lower salary while starting a business. If your marginal bracket drops from 24 percent to 12 percent, converting during that window is a bargain. You are paying tomorrow’s tax at today’s discounted rate.

Before RMDs start. If you are in your 60s and staring at a traditional IRA that is going to force big required distributions later, converting some of it in your lower-income sixties can lower those forced withdrawals and the tax hit that comes with them.

Before a move to a higher-tax state. If you live in a no-income-tax state now (Texas, Florida, Tennessee, Nevada, and a few others) and are planning a move to California or New York, converting before the move can save you the state-level tax on that amount forever.

When you expect higher rates broadly. The current federal brackets are historically low. If you believe (as many economists do) that rates have nowhere to go but up eventually, paying today’s rate on some of your balance is cheap insurance.

The years to skip a conversion: any year you are already in a high marginal bracket, a year where you are near a phase-out for a benefit you rely on (ACA premium tax credits, IRMAA thresholds, FAFSA aid, student loan payments tied to AGI), and any year where you cannot pay the resulting tax from a separate cash account without draining an emergency fund.

The downsides nobody puts on the marketing page

Fidelity’s own landing page for the product mentions “consider the tax implication” and moves on. Fair. Every downside comes back to the same core fact: the amount you convert is added to your taxable income for the year, and that number cascades into things you might not be tracking.

The second-order costs I have watched blindside real humans:

• ACA premium tax credits vanish. If you buy health insurance on the marketplace and your income creeps over the cliff, a conversion can cost you thousands in subsidy in a single year. That loss can easily exceed the conversion’s benefit.
• IRMAA on Medicare premiums. Once you are on Medicare, higher AGI two years earlier means higher Part B and Part D premiums. A big conversion in your mid-60s can push you into a surcharge bracket you do not see until you are already paying it.
• Student aid math shifts. If you have kids applying to college, a conversion year is a bad FAFSA year. Plan around it.
• State tax you did not budget for. If your state taxes IRA income (most do), the conversion is state-taxable too. That number is easy to forget when Fidelity only shows you the federal withholding option.
• No recharacterization. Before 2018, you could undo a conversion. You cannot anymore. Once the numbers are entered and confirmed, the tax bill is real.

None of these are reasons to never convert. They are reasons to run the math before you click submit, ideally with a tax pro who has looked at your full return.

A Roth conversion is a tool for buying certainty about your tax rate. It only makes sense if today’s rate is a better deal than tomorrow’s, and only if you can pay the bill from outside the account without wrecking the rest of your plan.

The pro-rata rule, in plain money terms

This is the single most common trap, and it is worth understanding before you touch anything. The pro-rata rule (technically the IRA aggregation rule) treats every traditional, SEP, and SIMPLE IRA you own as one giant IRA for tax purposes on conversion day.

Say you have $95,000 of pre-tax money in a traditional IRA, plus a $5,000 after-tax “backdoor” contribution sitting in another traditional IRA waiting to be converted. You might think you can convert just the $5,000 and pay no tax on it, since you already paid tax on that money. You cannot. The IRS looks at both accounts together, sees the pool is 95 percent pre-tax, and taxes 95 percent of anything you convert. That $5,000 conversion becomes $4,750 of taxable income and only $250 truly tax-free.

The workaround: before doing a backdoor Roth, roll any pre-tax IRA balances into a current 401(k) if the plan accepts them, which empties the IRA “pool” and makes the after-tax dollars convert cleanly. This is fiddly and worth asking a CPA about. It is also the reason “the biggest Roth conversion mistake” is such a Googled question. Most people who tripped this got surprised at tax time, and there is no going back.

The five-year rule (yes, there are two of them)

The five-year rule sounds like one thing. It is actually two, and mixing them up is how people get slapped with penalties they did not know existed.

Rule one, on earnings. A Roth IRA has to have been open for five tax years before any earnings can come out tax-free, no matter your age. If you opened your first Roth in 2026, the earnings clock finishes on January 1, 2031. Contributions you can always take out; growth is what the clock protects.

Rule two, on each conversion. Every conversion you do has its own five-year clock, and if you touch the converted principal before that clock finishes AND you are under age 59½, you pay a 10 percent penalty on it. If you convert $20,000 this year and pull that $20,000 out at age 55 next year, you owe $2,000 in penalty, on top of any earnings tax. Once you are 59½, both clocks matter less, but the earnings-side five-year rule still applies.

The plain takeaway: money you convert is money you should plan to leave alone for at least five years, and ideally until 59½. If you might need it sooner, a conversion is not the right home for it.

How to do a Roth conversion at Fidelity, step by click

Once you have decided a conversion makes sense and you know how much to move, Fidelity’s process is one of the cleaner ones in the industry. You need a Fidelity traditional IRA and a Fidelity Roth IRA already open. If you do not have the Roth side yet, open one first (it takes about ten minutes on their site) and let it settle.

With both accounts open, the flow inside Fidelity.com looks like this:

• Sign in and open your traditional IRA. Click into the account, look for the “Transfer” or “Convert to Roth IRA” option in the account’s action menu.
• Choose the source and destination accounts. Traditional IRA on the left, your Fidelity Roth IRA on the right. Confirm you are the owner of both.
• Enter the amount you want to convert. You can enter a dollar amount or a percentage. Do not just type in a round number without doing the tax math first.
• Pick your tax withholding. Fidelity will ask if you want to withhold federal (and sometimes state) tax from the conversion. Say no if you can afford to (more on this in the next section).
• Review the acknowledgment screen. Fidelity shows you the tax implications and the no-recharacterization warning. Read it. Really.
• Submit. The money and the shares move that day if you submit before the market close cutoff (Fidelity’s own hard deadline for the tax year is 4 p.m. Eastern on December 31).

For an old workplace plan you are trying to convert directly, the process is different: call 800-343-3548, or roll the 401(k) to a Fidelity traditional IRA first and then convert from there. If you are still deciding what to do with an old 401(k) balance, my write-up on how a 401(k) plan actually works and where the free money hides is a useful sanity check before you move anything.

The tax bill: pay it from outside the IRA

Here is the rule that separates a good conversion from a great one. When Fidelity asks whether you want to withhold tax from the conversion itself, the default temptation is to say yes. It feels simple: pay the tax right out of the money that is moving anyway. Do not do that if you can possibly avoid it.

There are two problems with saying yes. First, any dollar Fidelity withholds is a dollar that never makes it into the Roth. You converted $20,000, they withheld $4,400, and your Roth balance is $15,600. You just shrank the whole reason you did this. Second, if you are under 59½, the withheld amount counts as an early withdrawal, and you owe a 10 percent penalty on it. The IRS charges you for the privilege of paying your own tax.

The move: pay the conversion tax out of a taxable brokerage account, your checking account, or an emergency fund cushion that you can rebuild. Every dollar of tax you cover from outside is another dollar of tax-free growth for the next thirty years. This is the single biggest lever people leave on the table.

If you are unsure how much tax to expect, the Fidelity Roth conversion calculator gives a rough estimate. So do the free versions from NerdWallet and any decent CPA’s software. Rough is fine; you will settle up on your actual return using IRS Form 8606, which is the form your tax software will prompt you to fill out if you converted.

The multi-year game plan (the conversion ladder)

Most people who benefit from Roth conversions do not do one big conversion. They do many small ones, spread across years, sized to fill a specific tax bracket without spilling over. This is called a Roth conversion ladder, and it is the strategy that turns “did I just make a mistake” into a boring long-term win.

The idea is bracket filling. Say you and your spouse expect to earn $80,000 of taxable income this year, and the top of the 12 percent federal bracket sits around $96,000 (adjust for the year). You have roughly $16,000 of room inside the 12 percent bracket. Convert $16,000. Every dollar of that conversion is taxed at 12 percent, not the 22 percent you would pay if you converted more and pushed into the next bracket. Next year, do it again with whatever room you have.

Over a decade of doing this, you move a huge chunk of your traditional IRA into Roth space at a below-average tax rate, without ever taking a single-year hit. This is a beautiful, boring move. For a look at how to think about the rest of your portfolio around the same time, my walkthrough on how to invest money in 2026 without losing your mind pairs well with a laddering plan.

Where the actual math lives (and what Dave Ramsey says)

Dave Ramsey, since it is a common question, is broadly a fan of Roth conversions, especially in low-income years. His audience skews toward “get the tax pain over with,” and the emotional appeal of never owing tax on this money again is real. That is defensible advice as a default, and for a lot of listeners it is the right call.

It is also not a substitute for running your own numbers. “Always convert everything” is not a plan, and treating any personality’s opinion as gospel skips over the three variables that actually decide the answer: your current marginal bracket, how many years the money has to compound before you touch it, and whether you can pay the tax from a source that is not the conversion itself. If a piece of advice ignores those three things, it is a slogan wearing a spreadsheet.

A rough “how much tax will I owe” gut check: on a $50,000 conversion, if you land in the 22 percent federal bracket, you are looking at roughly $11,000 of federal tax on the conversion, plus state tax if your state charges it, plus whatever second-order costs (IRMAA, ACA) that year triggers. Do that estimate before you click. The exact number lands on Form 8606 at tax time, but you should never be surprised by the general shape of it.

A Fidelity Roth conversion is not a get-rich move and it is not a shortcut. It is a small piece of paperwork that, done in the right year with the tax bill paid from the right account, compounds into real money you never owe tax on again. The people who benefit most are the ones who did the math, ran the numbers past a professional once, and then treated the whole thing like a chore, not a lottery ticket. Spend on purpose, pay tax on purpose, and let the boring parts do their job.

📌 Save this one for next January when the conversion window closes on December 31 and you need the calm walkthrough, not the tax-forum panic. And drop a comment: what is the piece of retirement math you wish someone had explained to you first?

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Who wrote this

Robby Naka writes The Millennial Budget, a no-shame take on money for people who want a great life now and later. He’s not a financial advisor, just a guy a little obsessed with spending on purpose and figuring out his own kind of rich. More about Robby. This article is general education, not financial or tax advice for your situation.