How a Roth conversion actually works

A Roth conversion means moving money from a traditional IRA, SEP-IRA, straightforward IRA, or a 401(k) into a Roth IRA. You withdraw the money from the pre-tax account, pay income tax on the amount you convert in that tax year, and deposit it into the Roth account. The money then grows tax-free, and you can withdraw it tax-free in retirement.

The IRS does not require your permission or approval before you convert. You initiate it yourself by contacting your financial institution — the bank, brokerage, or plan administrator that holds your account. There is no process form, no waiting period, and no income limit that stops you from converting (unlike traditional Roth contributions, which have income caps).

The conversion is permanent. Once the money is in the Roth, you cannot move it back to a traditional account. You can undo a conversion only within a narrow window — until the tax-filing important date of the year after the conversion — through a process called a recharacterization, but this is rare and requires specific steps with your financial institution.

Key Takeaways

  • You initiate a Roth conversion by contacting your financial institution directly; there is no government form to file or approval to receive.
  • You owe income tax on the full amount you convert in the year you convert it, calculated at your ordinary income tax rate.
  • The conversion happens in two steps: withdraw from the pre-tax account, then deposit into the Roth account, usually within 60 days.
  • You report the conversion on your tax return using Form 8606, which you file when you submit your 1040.
  • If you have other traditional IRAs, SEP-IRAs, or straightforward IRAs, the IRS treats them as one pool for tax purposes, which can increase your tax bill unexpectedly.

Step 1: Decide how much to convert and when

Before you contact your financial institution, decide the dollar amount you want to move. You can convert part of an account or all of it. There is no minimum or maximum, but converting a large amount in a single year will push you into a higher tax bracket and increase your tax bill significantly.

Many people convert in years when their income is lower than usual — after retirement, during a sabbatical, or in a year when they took a loss in their business. Some convert small amounts every year to spread the tax hit across multiple years. There is no rule about timing; it depends on your income and tax situation.

If you have a 401(k) through an employer, check whether your plan allows in-service conversions. Not all plans do. If yours does not, you can convert only after you leave the job or reach age 59½, depending on the plan's rules. If you have already left the job, you can convert when ready.

Step 2: Contact your financial institution and request the conversion

Call or log into the website of the bank, brokerage, or plan administrator that holds your traditional IRA or 401(k). Ask to speak with someone in the IRA or retirement accounts department. Tell them you want to do a Roth conversion and give them the dollar amount.

They will ask which account the money is coming from and confirm where it should go. If you do not yet have a Roth IRA, they can open one for you at the same institution, or you can open one elsewhere first. The money does not have to stay at the same place — you can convert from one institution to another.

Ask the financial institution whether they will handle the conversion as a direct transfer (also called a trustee-to-trustee transfer) or whether you will receive a check. A direct transfer is simpler and avoids the 60-day rule. If they send you a check, you have 60 days to deposit it into a Roth IRA, or the IRS will treat it as a withdrawal and you will owe a 10% penalty if you are under 59½.

Step 3: Complete the conversion and confirm receipt

If your financial institution handles the transfer directly, the money moves electronically and usually arrives within one to five business days. If you receive a check, deposit it into your Roth IRA account within 60 days. Keep the deposit receipt.

Once the money arrives in the Roth account, log in and verify the balance. Your financial institution should also send you a confirmation statement showing the conversion. Save this statement — you will need it to complete your tax return.

If the conversion took place late in the year, the confirmation may not arrive until January. Do not file your tax return until you have the statement in hand. The statement will show the date of the conversion and the amount, which you must report accurately on Form 8606.

Understanding the tax bill and the pro-rata rule

You owe income tax on the amount you convert, calculated at your ordinary income tax rate for that year. If you convert $50,000 and you are in the 24% federal tax bracket, you will owe approximately $12,000 in federal income tax (plus state tax if your state has an income tax). This tax is due when you file your return the following spring.

The tax bill is larger if you have other traditional IRAs, SEP-IRAs, or straightforward IRAs. The IRS applies the pro-rata rule, which treats all your traditional IRAs as a single account for tax purposes. If you have $100,000 in a traditional IRA earning interest and you convert $50,000 to a Roth, the IRS calculates what percentage of your total traditional IRA balance is pre-tax money (contributions you deducted) and what percentage is after-tax money (contributions you did not deduct). You pay tax only on the pre-tax portion of the $50,000.

This rule catches many people off guard. If you have a large traditional IRA and a small after-tax contribution, converting looks cheaper than it actually is. Work through the calculation with a tax professional before you convert, or use the IRS worksheet on Form 8606 instructions to estimate your tax bill.

Reporting the conversion on your tax return

When you file your federal income tax return, you must report the conversion on Form 8606: Nondeductible IRAs. This form calculates how much of your conversion is taxable and how much is not (the after-tax portion). You attach Form 8606 to your Form 1040.

Your financial institution will send you a Form 1099-R in January showing the conversion. This form reports the gross amount you converted. Form 8606 is where you account for any after-tax contributions and calculate your actual tax liability.

If you do not file Form 8606, the IRS will assume the entire conversion is taxable, even if part of it came from after-tax contributions. This can result in double taxation — you pay tax on the conversion and again when you withdraw the after-tax portion in retirement. Filing Form 8606 is not optional if you have any after-tax money in your traditional IRAs.

What happens if you have multiple IRAs or a 401(k)

If you have more than one traditional IRA, the pro-rata rule applies to all of them together. If you have a 401(k) at work, it is treated separately — the pro-rata rule does not include 401(k) balances. This creates a planning opportunity: if you have a large traditional IRA and a 401(k), you can roll the traditional IRA into the 401(k) first (if your plan allows it), then convert from the 401(k) to avoid the pro-rata rule.

If you have a SEP-IRA or straightforward IRA, those are also included in the pro-rata calculation with your traditional IRAs. straightforward IRAs have an additional restriction: you cannot convert during the first two years you own the account. After two years, the pro-rata rule applies.

Before you convert, list all your retirement accounts and their balances. Ask your financial institutions whether any of them allow rollovers into a 401(k). This step can save you thousands in taxes if your situation qualifies.

Frequently Asked Questions

Can I undo a Roth conversion if I change my mind?

Yes, but only within a narrow window. You can recharacterize (undo) a conversion until the tax-filing important date of the year after the conversion — normally April 15 of the following year. Contact your financial institution and ask them to reverse the conversion. You will owe no tax on the amount reversed, but you must file Form 8606 to report the recharacterization to the IRS.

Do I pay the conversion tax from the conversion money or from my other accounts?

You pay it from whatever money you have available. The tax is not withheld automatically, so if you convert $50,000 and owe $12,000 in tax, you must have $12,000 elsewhere to pay the IRS. If you use money from the conversion itself to pay the tax, you are converting less than you intended, and the pro-rata calculation changes. Most people pay the tax from savings or other income to keep the full amount in the Roth.

What if I convert and then my income is higher than I expected that year?

Your tax bill is based on the amount you convert, not on your total income. If you convert $50,000, you owe tax on $50,000 at your marginal rate, regardless of whether your income was $60,000 or $160,000 that year. However, a larger conversion can push you into a higher tax bracket, which increases the tax rate on the conversion itself and on your other income. This is why many people convert in lower-income years.

Can I convert a 401(k) directly to a Roth without going through a traditional IRA?

Yes, if your 401(k) plan allows it. This is called a direct Roth conversion or in-plan Roth conversion. Ask your plan administrator whether this option is available. If it is, you avoid the pro-rata rule entirely because the money never touches a traditional IRA. If your plan does not allow it, you must roll the 401(k) to a traditional IRA first, then convert to a Roth.

Do I owe the 10% early withdrawal penalty if I convert before age 59½?

No. Roth conversions are not subject to the 10% early withdrawal penalty, even if you are under 59½. However, if you withdraw the converted money from the Roth account within five years of the conversion, you may owe the penalty on the earnings portion. The five-year rule is separate from the pro-rata rule and applies to each conversion separately.