Yes, you can convert a 401(k) to a Roth IRA, but the process and tax consequences depend on whether your 401(k) is with a current employer, a former employer, or already rolled over

A 401(k)-to-Roth conversion moves money from a traditional 401(k) into a Roth IRA. The conversion itself is straightforward: you instruct your 401(k) plan administrator to send the funds to a Roth IRA you've opened, and the money moves directly. What makes conversion complicated is the tax bill. When you convert, you owe income tax on the full amount you move — as if you'd withdrawn it that year. The IRS taxes it at your ordinary income tax rate, which can push you into a higher tax bracket. You pay this tax from your own pocket, not from the conversion amount itself.

Whether you can convert depends first on your employment status. If you still work for the company that sponsors your 401(k), most plans do not allow in-service conversions to a Roth IRA — you'd have to wait until you leave the job, retire, or reach age 59½. If you've left the employer, you can convert at any time. If your 401(k) is already rolled into a traditional IRA, conversion is always available. The second factor is your income: there is no income limit on conversions themselves, but a high income can trigger the pro-rata rule, which affects how much of your conversion is taxed.

Key Takeaways

  • You can convert a 401(k) to a Roth IRA only if you've left the employer, reached age 59½, or your plan allows in-service conversions — most do not.
  • You owe income tax on the full amount converted in the year you convert, calculated at your ordinary tax rate.
  • If you have other traditional IRAs or SEP IRAs, the pro-rata rule may increase your tax bill by treating all your traditional IRA balances as one pool.
  • You can convert as much or as little as you want, and there is no income limit on conversions, though high earners may face higher tax consequences.
  • After conversion, the money in your Roth IRA grows tax-free and you can withdraw earnings without penalty after age 59½ and five years of Roth ownership.

When your 401(k) plan allows conversion while you're still employed

Most 401(k) plans do not permit in-service conversions to a Roth IRA while you remain employed. Your plan document controls this, and you can ask your HR or benefits department whether yours allows it. If it does, you can convert without leaving the job. If it does not, you have three paths: wait until you leave the employer, wait until you turn 59½ (some plans allow conversions at that age), or roll the 401(k) into a traditional IRA and convert from there.

Rolling into a traditional IRA first, then converting to a Roth, is a common workaround. You contact your 401(k) administrator and request a direct rollover to a traditional IRA at a bank or brokerage. Once the money lands in the traditional IRA, you can convert to a Roth when ready. This route takes a few business days but avoids waiting until retirement or job separation.

How the pro-rata rule affects your tax bill

The pro-rata rule is the most common surprise in conversions. If you have any money in traditional IRAs, SEP IRAs, or straightforward IRAs — whether you're still contributing to them or not — the IRS treats all your traditional IRA balances as one pool for tax purposes. When you convert, a portion of the conversion is taxed based on the ratio of pre-tax money to after-tax money across all your traditional accounts.

Here's the math: suppose you have $100,000 in a traditional IRA (all pre-tax contributions) and you want to convert $50,000 from your 401(k) to a Roth. The IRS sees $150,000 in traditional accounts total. Of that, $100,000 is pre-tax. That's 66.7% pre-tax. So 66.7% of your $50,000 conversion — about $33,350 — is taxable. The other $16,650 is treated as after-tax basis and is not taxed again. If you have no traditional IRA balances, the entire conversion is taxable.

The pro-rata rule applies only to IRAs, not to 401(k)s. If you have a 401(k) with your current employer and a traditional IRA, they are not pooled together. This is why some people roll their traditional IRA into their 401(k) before converting — it removes the IRA from the pro-rata calculation. Not all 401(k) plans accept rollovers in, so check with your plan administrator first.

The tax you owe and when to pay it

When you convert, you owe federal income tax on the taxable portion in the year of conversion. The 401(k) administrator does not withhold this tax automatically — you have to pay it yourself by April 15 of the following year (or when you file your tax return). You can ask the administrator to withhold a portion of the conversion amount to cover estimated taxes, but most people pay from a separate bank account to avoid reducing the amount that actually moves to the Roth.

The tax is calculated at your ordinary income tax rate for that year. If you convert $50,000 and your tax bracket is 24%, you owe $12,000 in federal tax. State income tax may explore as well, depending on where you live. Some states do not tax retirement income, while others tax conversions as ordinary income. The larger your conversion, the more it can push your income into a higher bracket, increasing the tax rate on the conversion itself and potentially on other income that year.

You have until December 31 of the year you convert to undo the conversion through a recharacterization — but only if your plan allows it and only if you do it before filing your tax return for that year. Recharacterization sends the money back to the 401(k) or traditional IRA, and you owe no tax. This is useful if the market drops after you convert and you want to avoid paying tax on money that's now worth less. However, recharacterization rules are strict, and not all plans permit them, so confirm with your administrator before converting.

Roth conversion ladder and the five-year rule

After you convert, the money sits in your Roth IRA under two separate five-year clocks. The first clock is the five-year holding period: you must own a Roth IRA for at least five tax years before you can withdraw earnings tax-free. This clock starts January 1 of the year you open your first Roth IRA, not the year you convert. If you open a Roth in 2024, the clock runs through December 31, 2028.

The second clock applies to conversions specifically. Money you convert can be withdrawn tax-free at any time — you already paid tax on it when you converted. But if you withdraw earnings that accumulated after the conversion, those earnings are subject to tax and a 10% penalty if you're under 59½, unless an exception applies. This is why some people use a Roth conversion ladder: they convert a portion each year, wait five years, then withdraw the converted amount (not the earnings) to live on. The earnings stay in the Roth to grow tax-free.

Comparing conversion timing: now versus later

The decision to convert depends on your current tax bracket, expected future tax bracket, and market conditions. If you're in a low-income year — between jobs, taking a sabbatical, or recently retired — converting then means paying tax at a lower rate. If you expect to be in a higher tax bracket in retirement, converting now locks in today's rate. Conversely, if you're in a peak earning year, converting adds to your taxable income and may not make sense.

Market timing also matters. If the market drops after you convert, the value of your Roth drops too, but you've already paid tax on the higher pre-drop value. Some people wait for a market correction to convert. Others convert steadily regardless of market conditions, treating it as a long-term tax strategy rather than a market bet. There is no single right answer — it depends on your situation, your tax bracket, and your timeline to retirement.

Frequently Asked Questions

Do I have to convert my entire 401(k) at once?

No. You can convert part of your 401(k) and leave the rest in place. Some people convert in stages over several years to spread the tax bill across multiple years and stay in a lower tax bracket. Your 401(k) administrator can process a partial conversion if you request it.

What happens if I convert and then go back to work for the same employer?

The conversion is permanent — you cannot undo it just because you return to the employer. The money stays in your Roth IRA and grows tax-free. However, if you had recharacterified the conversion before filing your tax return, you could have sent it back to the 401(k) before returning to work.

Can I convert my 401(k) if I'm still making contributions to it?

Only if your plan allows in-service conversions. Most plans do not. If yours does not, you can roll the 401(k) into a traditional IRA and convert from there, or wait until you leave the employer or reach age 59½.

Will converting affect my Social Security benefits or Medicare premiums?

Conversions count as taxable income for the year you convert, which can increase your Modified Adjusted Gross Income (MAGI). A higher MAGI may trigger higher Medicare premiums (IRMAA surcharges) and can affect how much of your Social Security is taxed. Plan conversions with this in mind if you're near Medicare age.

What if I convert and the market drops before I file my taxes?

You can recharacterify the conversion — send the money back to your 401(k) or traditional IRA — if you do so before filing your tax return and your plan allows recharacterification. This erases the tax bill. After the filing important date, recharacterification is no longer available, and you're locked into the tax you owe on the original conversion amount.