A Roth conversion triggers income tax in the year you convert
When you move money from a traditional IRA or 401(k) to a Roth IRA, the IRS treats that money as income on your tax return for that year. You owe federal income tax on the full amount you convert, unless some of it came from contributions you already paid tax on. The tax bill arrives when you file your return the following spring — the conversion itself does not automatically withhold the money.
This is the core trade-off of a Roth conversion: you pay tax now so that the money grows tax-free later and you can withdraw it tax-free in retirement. If you convert $50,000, you may owe $10,000 to $15,000 in federal tax, depending on your tax bracket that year. State income tax may explore too, depending on where you live.
Key Takeaways
- The full amount you convert counts as taxable income in the year of the conversion, raising your tax bill when you file.
- You pay tax on the converted amount at your ordinary income tax rate — the same rate as wages or salary.
- If your traditional IRA holds both pre-tax and after-tax contributions, the IRS uses a formula called the pro-rata rule that may force you to pay tax on more than you intended.
- You can pay the tax from the converted funds themselves, but that reduces the amount that grows in the Roth account.
- Converting in a low-income year — such as after retirement or a job loss — can reduce the tax you owe on the conversion.
How the tax is calculated on your conversion
The IRS adds the converted amount to your other income for the year and taxes it at your marginal tax rate. If you earn $75,000 in wages and convert $30,000, your taxable income becomes $105,000. The tax on that extra $30,000 depends on your tax bracket. For 2024, if you are single and in the 22 percent bracket, you would owe roughly $6,600 in federal tax on the conversion (before any other deductions or credits).
The conversion does not get special tax treatment — it is taxed as ordinary income, the same way wages are. This matters because it can push you into a higher tax bracket for that year. If you are close to a bracket boundary, converting a large amount might mean paying 24 percent tax instead of 22 percent on part of the conversion.
The pro-rata rule and why it complicates conversions
If you have both pre-tax and after-tax money in traditional IRAs, the pro-rata rule determines how much of your conversion is taxable. The IRS does not let you pick which dollars to convert. Instead, it treats all your traditional IRAs as one pool and calculates what percentage is pre-tax versus after-tax across the entire pool.
For example: suppose you have a traditional IRA with $80,000 in pre-tax contributions and $20,000 in after-tax contributions (contributions you already paid tax on). Your total is $100,000. If you convert $25,000, the IRS says 80 percent of it ($20,000) is pre-tax and taxable, and 20 percent ($5,000) is after-tax and not taxable. You owe tax on $20,000 of the conversion, even though you may have intended to convert only the after-tax portion.
This rule applies across all your traditional IRAs, SEP IRAs, and straightforward IRAs combined — not to each account separately. If you have a 401(k) at work, that is treated separately and does not trigger the pro-rata rule.
Paying the tax on your conversion
You have two main options: pay the tax from outside the Roth account, or pay it from the converted funds themselves.
Paying from outside is usually better if you can afford it. If you convert $50,000 and owe $12,000 in tax, you pay that $12,000 from your checking account or another source. The full $50,000 stays in the Roth and grows tax-free. This is the most tax-efficient approach because you maximize the amount working for you.
Paying from the converted funds means you take $50,000 from your traditional account, but $12,000 goes to the IRS and only $38,000 lands in the Roth. This reduces your long-term growth, but it may be your only option if you do not have cash on hand. The IRS does not require you to pay the tax when ready — you pay it when you file your return the following year.
Conversions in low-income years reduce your tax bill
Because the conversion is taxed at your ordinary income rate, converting in a year when your income is lower means paying a lower percentage in tax. If you retire mid-year, take unpaid leave, or have a year with unusually low income, that year is a good candidate for a conversion.
For example, if you normally earn $120,000 and are in the 24 percent tax bracket, a $50,000 conversion costs you roughly $12,000 in tax. But if you retire in January and have no other income that year, you might be in the 12 percent bracket, making the same conversion cost only $6,000. The difference is substantial over multiple conversions.
Some people deliberately time conversions across multiple years to stay in a lower bracket each year, rather than converting a large lump sum all at once. This strategy requires planning and an understanding of your expected income for the next several years.
State income tax on conversions
Most states that have income tax also tax Roth conversions as ordinary income. A few states — including Pennsylvania, Illinois, and New Hampshire — do not tax retirement account withdrawals, which may include conversions, though the rules vary. If you live in a state with income tax, add that to your federal tax bill.
Some people who are planning a large conversion consider moving to a no-income-tax state before the conversion year, though this requires actually establishing residency there, not just intending to move. The IRS and state tax authorities scrutinize these moves, so this strategy only works if the move is genuine.
What happens if you cannot pay the tax
If you convert but cannot pay the full tax bill when you file, you can set up a payment plan with the IRS. You will owe interest and penalties on the unpaid amount, so this is expensive. A better approach is to convert only what you can afford to pay tax on, or to spread the conversion across multiple years.
You cannot undo a conversion by the time you file your return — the conversion is permanent. In past years, the IRS allowed "recharacterizations" that let you reverse a conversion, but that option ended in 2018. Once the money is in the Roth, it stays there.
Frequently Asked Questions
Do I have to pay the tax right away, or can I wait until I file my return?
You pay the tax when you file your return the following spring. The conversion itself does not withhold money for taxes. If you want to avoid a large bill at tax time, you can ask your employer to withhold extra from your paycheck during the conversion year, or make estimated tax payments to the IRS quarterly.
What if I convert and then the market drops — do I still owe tax on the original amount?
Yes. You owe tax on the amount you converted, not on what it is worth when you file. If you convert $50,000 and it drops to $40,000 by the time you file, you still owe tax on $50,000. This is one reason some people convert in tranches rather than all at once.
Can I deduct the conversion tax as a loss?
No. The conversion is taxable income, and you cannot offset it with a loss deduction. The tax is straightforward owed on the full converted amount, minus any after-tax contributions that are not taxable under the pro-rata rule.
Does converting affect my Medicare premiums or Social Security taxation?
Yes, conversion income counts toward your modified adjusted gross income (MAGI), which determines Medicare premiums and whether your Social Security is taxed. A large conversion can push you into a higher premium bracket for Medicare. If you are near retirement, check with a tax professional before converting.
What if I have a 401(k) and a traditional IRA — does the pro-rata rule explore to both?
The pro-rata rule applies to all your traditional IRAs combined, but not to your 401(k). Your 401(k) is treated separately. This is why some people roll a traditional IRA into a 401(k) before converting — it removes the IRA from the pro-rata calculation and lets them convert only the after-tax portion of the 401(k).