How Roth Conversions Are Taxed: What You Owe in the Year You Convert

You pay ordinary income tax on the converted amount in the year you move the money

When you convert money from a traditional IRA, SEP-IRA, or SIMPLE IRA to a Roth IRA, the IRS treats the converted amount as taxable income on your federal tax return for that year. You do not pay the tax from the converted funds themselves—you owe it separately, from other money you have on hand. The tax bill arrives when you file your return the following spring, not when you execute the conversion.

The tax you owe depends on how much you convert and your total income for the year. A conversion of $50,000 does not automatically mean a $50,000 tax bill; it means $50,000 gets added to your taxable income, and you pay tax on that amount at your marginal rate. If you are in the 24 percent federal bracket, converting $50,000 costs roughly $12,000 in federal tax. State income tax, where your state has one, applies on top of that.

The conversion itself is not optional tax-wise. Once the money lands in the Roth account, the IRS has already decided it is taxable income for that year. You cannot undo the tax consequence by moving the money back—though you can undo the conversion itself through a process called a recharacterization, which reverses the transaction and erases the tax bill, but only under specific circumstances and with strict timing rules.

Key Takeaways

• Converted amounts are taxed as ordinary income at your marginal tax rate in the year the conversion happens, not spread across multiple years.
• You pay the tax bill separately from the converted funds, usually when you file your return the following April.
• The pro-rata rule applies if you hold both pre-tax and after-tax money in any IRA; you cannot convert only the after-tax portion without triggering tax on a portion of the pre-tax balance.
• Conversions can push you into a higher tax bracket or trigger Medicare premium surcharges, so timing and amount matter significantly.
• A recharacterization can undo a conversion and erase the tax bill, but only if completed by the tax-filing deadline of the following year.

The pro-rata rule: why you cannot convert only the after-tax money

If you have both pre-tax and after-tax contributions sitting in any of your IRAs combined, the pro-rata rule forces you to treat a conversion as coming proportionally from both. This rule applies across all your IRAs as one group—you cannot isolate a single account and convert only its after-tax portion.

Here is a concrete example: suppose you have $80,000 in a traditional IRA (pre-tax contributions and earnings) and $20,000 in a SEP-IRA (also pre-tax). You also have $10,000 in a Roth IRA that you opened years ago. You want to convert the $10,000 in after-tax basis you contributed to a backdoor Roth account. The IRS sees your total IRA balance as $90,000 pre-tax and $10,000 after-tax. When you convert $10,000, the pro-rata rule says $10,000 × (90/100) = $9,000 of it is taxable, and only $1,000 is tax-free. You owe tax on $9,000 of the conversion.

The pro-rata rule is why people with large pre-tax IRA balances often cannot execute a backdoor Roth conversion without a significant tax bill. The only way around it is to move the pre-tax money out of the IRA system entirely—usually by rolling it into a workplace 401(k) plan that accepts rollovers—before you convert the after-tax money.

How conversions interact with tax brackets and Medicare premiums

A conversion can push your total income into a higher federal tax bracket, meaning you pay a steeper rate not just on the converted amount but potentially on other income too. The effect depends on your filing status and other income sources. Someone converting $40,000 in a year when they already earned $100,000 in wages may jump from the 22 percent bracket into the 24 percent bracket, paying 24 percent on the last portion of the conversion.

Conversions also affect Modified Adjusted Gross Income (MAGI), which determines Medicare Part B and Part D premiums if you are over 65 or approaching that age. Higher MAGI can trigger income-related monthly adjustment amounts (IRMAA), which are surcharges added to your Medicare premiums. These surcharges are based on your MAGI from two years prior, so a conversion in 2024 affects your 2026 Medicare costs. For someone on Medicare, a large conversion can cost thousands in additional premiums over two years.

This is why many people time conversions strategically—converting in years when their income is lower, or spreading conversions across multiple years to stay below bracket thresholds or MAGI limits. A financial or tax professional can model the impact for your specific situation.

State income tax on conversions

Most states that have an income tax treat Roth conversions the same way the federal government does: as taxable income in the year the conversion occurs. You owe state tax on the converted amount at your state's rate, in addition to federal tax. A few states have no income tax (Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, Wyoming), so residents of those states owe only federal tax on a conversion.

If you move to a different state after a conversion but before you file your return, tax residency rules determine which state gets to tax the conversion. Generally, the state where you lived on December 31 of the conversion year taxes the income. This matters if you are moving from a high-tax state to a no-tax state or vice versa, because the timing of your move relative to the conversion can shift your tax bill significantly.

Recharacterization: undoing a conversion and erasing the tax

A recharacterization is a formal reversal of a Roth conversion. You instruct your IRA custodian to move the converted funds (plus or minus any earnings or losses since the conversion) back into a traditional IRA. Once the recharacterization is complete, the IRS treats the conversion as if it never happened, and you owe no tax on it.

Recharacterizations are useful when market conditions change after you convert. If you convert $50,000 and the market drops 20 percent before you file your return, the converted balance is now worth $40,000. A recharacterization erases the tax bill on the original $50,000, even though you only have $40,000 to move back. You can then reconvert later if you wish, locking in the lower value for tax purposes.

The deadline to recharacterize is the tax-filing deadline of the year following the conversion—normally April 15, though it can be extended to October 15 if you file an extension. You must notify your IRA custodian in writing and include the recharacterization on your tax return (or an amended return if you already filed). Missing the deadline means the conversion stands, and you owe the tax regardless of market performance.

Withholding and estimated tax payments

When you convert, your IRA custodian does not automatically withhold tax from the converted funds. The money moves to your Roth account in full, and you are responsible for paying the tax bill when it comes due. If you do not set aside money to cover the tax, you may face a shortfall when you file your return.

If the tax bill is large relative to your other income, you may need to make an estimated tax payment to the IRS before year-end to avoid penalties. Estimated payments are due on April 15, June 15, September 15, and January 15 of the following year. Your tax software or a tax professional can calculate whether you need to make these payments based on your total expected income and withholding for the year.

Some people pay the conversion tax from the converted funds themselves—for example, converting $50,000 but only moving $40,000 to the Roth and using $10,000 to pay the tax bill. This is allowed, but it reduces the amount growing tax-free in the Roth account and counts as a taxable distribution from the traditional IRA if you are under 59½.

Conversions and the net unrealized appreciation rule

If you hold company stock in a traditional IRA, the conversion is straightforward: the stock moves to the Roth at its fair market value on the conversion date, and that value is taxable income. However, if you hold company stock in a 401(k) plan and roll it to an IRA before converting, you lose access to the net unrealized appreciation (NUA) strategy, which allows you to defer tax on the stock's growth until you sell it.

NUA is a separate tax strategy that applies only to 401(k) plans, not IRAs. If you have company stock in a 401(k) and are considering a conversion, consult a tax professional before rolling the stock into an IRA, because the move may cost you significant tax savings down the road.

Frequently Asked Questions

Can I convert just a portion of my IRA to avoid a large tax bill?

Yes, you can convert any amount you choose, but the pro-rata rule still applies if you hold pre-tax money in any IRA. Converting $10,000 instead of $50,000 reduces your tax bill proportionally, but it does not eliminate the pro-rata calculation. If you want to avoid the pro-rata rule entirely, you must move all pre-tax IRA money into a 401(k) plan first.

What happens if I cannot pay the tax bill by April 15?

You can request a payment plan from the IRS, which allows you to pay the tax in installments over time. Interest and penalties accrue on the unpaid balance. Alternatively, some people borrow money to pay the tax bill in full by the deadline, then repay the loan over time. Paying late triggers penalties and interest, so it is worth exploring payment options before the deadline.

Does a conversion count as income for Social Security taxation?

A Roth conversion increases your Modified Adjusted Gross Income (MAGI), which can trigger taxation of your Social Security benefits if your combined income exceeds certain thresholds. The thresholds are $25,000 for single filers and $32,000 for married filing jointly. If you are close to these limits, a large conversion could push you over and result in up to 85 percent of your benefits becoming taxable.

Can I undo a conversion if I change my mind after filing my return?

If you filed your return without recharacterizing, you can still file an amended return (Form 1040-X) to claim a recharacterization, but only if you are within the statute of limitations—generally three years from the original filing date. You must also complete the recharacterization with your custodian before filing the amended return. After the three-year window closes, the conversion is permanent and cannot be reversed for tax purposes.

Do I have to report a conversion on my tax return?

Yes. You report the conversion on Form 8606 (Nondeductible IRAs), which calculates how much of the conversion is taxable based on your total IRA balances and any pre-tax contributions. Form 8606 attaches to your Form 1040. If you recharacterize, you report that on Form 8606 as well. Failing to file Form 8606 can result in penalties, even if you reported the conversion correctly elsewhere on your return.