Roth IRA Conversion Rules

Anyone can convert a Traditional IRA to a Roth IRA, regardless of income, at any age. There is no annual limit on how much you can convert — you could move $1 million into a Roth in a single year if you have the funds. The price: you'll owe income tax on the amount converted in the year you do it. Once converted, the money grows tax-free forever. Conversions are permanent — since 2018, you cannot undo them through recharacterization.

What Is a Roth Conversion?

A Roth conversion is the process of moving money from a pre-tax retirement account into a Roth IRA. The converted money loses its pre-tax status—you pay income tax on it immediately—but then it grows tax-free forever inside the Roth.

The most common conversion is Traditional IRA to Roth IRA. But conversions can also happen from:

• SEP IRA to Roth IRA — if you're self-employed and have a SEP, you can convert.
• SIMPLE IRA to Roth IRA — allowed only if the SIMPLE has been held for at least 2 years. Converting within 2 years triggers a 10% penalty on the pre-tax portion.
• 401(k), 403(b), 457(b) to Roth IRA — available if your plan allows "in-service distributions" or after you leave the employer.
• 401(k) to Roth 401(k) — if your employer plan has a Roth 401(k) option, you can roll pre-tax funds directly (though this still triggers ordinary income tax).

Why Convert? The Tax Rate Arbitrage

The conversion strategy is fundamentally simple: if you believe you'll be in a higher tax bracket in retirement than you are today, converting now at a lower rate saves taxes over your lifetime. Conversions exploit a window of opportunity.

Consider a 55-year-old who retires early, has no income, and won't touch Social Security until 70. For 15 years, they're in a low tax bracket. During that window, they could convert $50,000 of Traditional IRA to Roth, pay 10-12% tax, and then—when Social Security kicks in and they enter the 24% bracket—that Roth grows completely tax-free. The arbitrage: they paid tax at 10-12% instead of 24%, saving 12-14 percentage points on the entire converted balance for the next 30 years.

For high earners expecting to maintain or increase income into retirement, or for legacy planning (passing tax-free wealth to heirs), conversions also serve strategic purposes beyond simple tax-rate matching.

No Income Limits or Annual Limits on Conversions

Unlike Roth IRA contributions, there is no income limit on conversions. A person earning $500,000/year can convert just as easily as someone earning $50,000. The IRS changed this rule specifically to enable the backdoor Roth strategy, which high earners use to circumvent contribution limits.

Conversions also have no annual dollar limit. You can convert $10,000, $100,000, or $1 million in a single year. The only constraint is the balance in your eligible accounts.

This is a major difference from contribution limits, which cap you at $8,600 annually (age 50+) or $7,500 (under 50) in 2026. Conversions let you move substantially more money into Roth tax-deferred growth.

How Conversions Are Taxed

When you convert funds from a Traditional IRA to a Roth, the converted amount is added to your taxable income for that tax year. This applies regardless of whether you actually withdraw the money or simply move it between custodians.

The IRS treats conversions as if you took a distribution and immediately recontributed it to a Roth IRA. For tax reporting, your broker will issue a Form 1099-R showing the conversion amount in Box 1, and you'll report this as a distribution on your tax return.

Example: Tax Impact of a $30,000 Conversion

Suppose you're single, have $40,000 in AGI (taxable income of $23,900 after the 2026 $16,100 standard deduction), and convert $30,000 from Traditional IRA to Roth. Your new taxable income is $53,900. The $30,000 conversion fills the remainder of the 12% bracket and pushes you just into the 22% bracket (2026 single 12% bracket ends at $50,400, per Rev. Proc. 2025-32):

• First $26,500 of conversion taxed at 12% = $3,180
• Next $3,500 of conversion taxed at 22% = $770
• Total tax owed: $3,950 (about 13.2% average effective rate on the $30,000)

Once in the Roth, that $30,000 (less the $3,950 you paid in taxes) grows tax-free indefinitely. If it doubles to $60,000 over 20 years, you owe $0 in taxes on the $30,000 gain.

Conversions Are Permanent (No Recharacterization)

Before 2018, you could convert a Traditional IRA to Roth, then recharacterize it back if you changed your mind or if the market declined and you wanted to avoid the conversion's tax bill. This was called a "do-over" strategy.

The Tax Cuts and Jobs Act of 2017 eliminated recharacterization of conversions effective January 1, 2018. Now, conversions are permanent. Once you convert, you cannot undo it.

This has significant planning implications: before converting, carefully consider whether you can afford the tax bill and whether the conversion aligns with your long-term strategy. Conversions are not timing plays anymore—they're strategic decisions with permanence.

Note: Recharacterization of contributions (not conversions) is still allowed. You can recharacterize a Roth contribution as Traditional (or vice versa) before the tax filing deadline. See Contribution Rules for details.

The Pro-Rata Rule and Embedded Tax Liability

Here's where conversions get complicated: the IRS treats all of your Traditional, SEP, and SIMPLE IRAs as a single pool for tax purposes. If you have pre-tax and after-tax money in this pool, conversions are taxed proportionally.

This is called the pro-rata rule, and it's one of the biggest conversion gotchas.

How the Pro-Rata Rule Works

Imagine you have three accounts totaling $100,000:

• Traditional IRA: $80,000 (pre-tax)
• SIMPLE IRA: $15,000 (pre-tax)
• After-tax (non-deductible) contribution: $5,000
• Total IRA universe: $100,000 (95% pre-tax, 5% after-tax)

You want to convert the $5,000 after-tax portion to Roth and avoid the tax. Sorry—the IRS doesn't allow this. Instead, the pro-rata rule says: 95% of any conversion is pre-tax (and thus taxable), 5% is after-tax (and thus tax-free).

If you convert $5,000, you owe tax on $4,750 (95% of $5,000) even though you were trying to convert only after-tax money. This is a major barrier to the backdoor Roth if you have existing pre-tax IRA balances.

For a detailed breakdown of the pro-rata rule and strategies to minimize it, see Pro-Rata Rule Guide.

The 5-Year Rule for Conversion Withdrawals

There are three separate 5-year rules for Roth IRAs. For conversions specifically, the rule is: if you're under age 59½, each conversion has its own 5-year clock. You cannot withdraw the converted amount (the principal) penalty-free until 5 years have passed.

Example: You convert $50,000 in 2026. The 5-year clock starts January 1, 2026, and ends December 31, 2030. If you withdraw the $50,000 in 2029 while under 59½, you'd owe a 10% early withdrawal penalty—despite the money technically being "in" a Roth. If you wait until 2031, no penalty applies.

Important note: The earnings generated by the conversion are still subject to the original account's 5-year rule (the one that started when you first opened a Roth). The conversion layer and the earnings layer have independent clocks.

For those age 59½ and above, the 5-year rule for conversions doesn't apply—you can withdraw conversions at any time penalty-free (though you still need the original account's 5-year rule to have been met for earnings to be tax-free).

For more details, see 5-Year Rule for Conversions.

Should You Convert? A Decision Framework

Bracket Filling: Maximizing the Conversion Window

A sophisticated conversion tactic is "bracket filling"—converting just enough to fill up your current tax bracket without moving into a higher one.

Example: You're single, have $30,000 in income, and the 12% bracket for single filers goes up to $50,400 in 2026 (per Rev. Proc. 2025-32). After the $16,100 standard deduction, your taxable income is $13,900, leaving $36,500 of room in the 12% bracket. Instead of converting $100,000, convert $36,500. You pay 12% tax on the entire conversion, minimize bracket creep, and still move money to Roth.

The math: $36,500 × 12% = $4,380 in taxes. If that $36,500 grows to $73,000 over 20 years, you've paid $4,380 in tax to save roughly $7,300–$10,200 in future taxes (depending on your future bracket).

This strategy requires knowing your exact tax bracket and remaining room, which is why working with a tax professional during conversion years is valuable.

Medicare IRMAA Impact: The Hidden Cost of Conversions

Here's a conversion gotcha many people miss: conversions increase your Modified Adjusted Gross Income (MAGI), which affects your Medicare Part B and Part D premiums through Income-Related Monthly Adjustment Amounts (IRMAA).

The key: IRMAA is calculated on your MAGI from two years prior. So a conversion in 2026 affects your Medicare premiums in 2028.

IRMAA Thresholds (2026)

Medicare Part B IRMAA surcharges kick in above certain MAGI levels. The 2026 brackets (based on your 2024 MAGI), per CMS and the SSA sliding scale (POMS HI 01101.020, effective December 2025):

Part D (prescription drug) surcharges use the same six-tier MAGI structure, added on top of whatever plan premium you're paying. For 2026, the Part D surcharges range from $14.50 up to $85.80 per month at the top tier.

For a single filer converting $100,000 who would otherwise have $80,000 MAGI, the conversion pushes them from the standard tier ($202.90) to Tier 3 ($527.50) — a jump of $324.60/month or $3,895/year, for both spouses if married and both on Medicare. That's a significant hidden cost that shows up two years after the conversion.

How to Pay Conversion Taxes: Critical Mistake to Avoid

When you convert $100,000 from Traditional IRA to Roth, you owe federal (and usually state) income tax on that $100,000. The question is: where does that tax money come from?

The right way: pay from external funds (savings, current income, a checking account). This maximizes the amount staying in the Roth.

The wrong way: have the custodian withhold the taxes from the converted amount. This is a major mistake because:

1. You still owe tax on the full amount. If you convert $100,000, you owe tax on $100,000. Withholding reduces the amount transferred to Roth, but doesn't reduce your tax bill. Example: You convert $100,000 with $20,000 withheld. You owe tax on $100,000, but only $80,000 lands in the Roth. You have to pay the remaining $20,000 from other funds anyway.
2. The withholding counts as a distribution. The IRS treats the withheld amount as if you withdrew it from your IRA. This affects ordering rules and could trigger unexpected 10% penalties if you're under age 59½.
3. Your Roth ends up smaller. If you convert $100,000 but withhold $20,000, your Roth gets $80,000 instead of $100,000. Over 20 years, that $20,000 difference compounds—at 7% growth, it becomes $77,000 you could have had.

State Tax Implications

Federal income tax applies to all conversions. But several states don't tax retirement income, including Roth conversions.

If you live in Florida, Texas, Nevada, South Dakota, Tennessee, Washington, or Wyoming (no state income tax), conversions have zero state tax impact. Some states treat Roth conversions favorably: Illinois exempts qualified retirement plan distributions (including Roth conversions) from state income tax under 35 ILCS 5/203. Mississippi exempts qualified retirement income for recipients who have separated from service and reached qualifying age. Pennsylvania generally does NOT tax traditional-to-Roth conversions under PA personal income tax. The PA Department of Revenue (REV-636) treats a Roth conversion fully rolled into the Roth IRA (directly or within 60 days) as a non-taxable event — regardless of the taxpayer's age. Any federal-withholding amount not deposited in the Roth remains PA-taxable. Later distributions of earnings before 59½ follow PA's cost-recovery method. Verify your state's specific rule before relying on this.

For other states, conversions are fully taxable at your state income tax rate. This can add 3-13% to the total tax bill, depending on your state. If you're considering a large conversion, doing it in a state with no income tax is a legal tax-saving tactic. Some retirees shift residence to low-tax states before executing large conversions.

The Backdoor Roth: Leveraging the No-Income-Limit Rule

The backdoor Roth is a specific conversion strategy for high earners. Because conversions have no income limit, you can:

1. Contribute $7,500 to a Traditional IRA
2. Immediately convert the $7,500 to Roth
3. Pay minimal tax (unless the conversion generates gains before the conversion)
4. Keep the $7,500 in Roth permanently

This lets high earners contribute to Roth despite income limits on direct Roth contributions. The catch: if you have pre-tax IRA balances, the pro-rata rule applies, and the conversion becomes inefficient.

For a full breakdown, see Backdoor Roth Guide.

NUA: The 401(k) Employer-Stock Strategy That Competes with Conversion

If your traditional 401(k) holds employer stock with significant appreciation, Net Unrealized Appreciation (NUA) treatment under IRC §402(e)(4) can be more tax-efficient than converting that stock to a Roth IRA. NUA is the most powerful retirement-tax strategy virtually no retail article mentions.

How NUA Works

Instead of rolling employer stock from your 401(k) into an IRA (which would convert all future growth into ordinary income), you distribute the stock in-kind to a regular taxable brokerage account as part of a “lump-sum distribution” of the entire 401(k) balance. You pay ordinary income tax only on the stock's cost basis (what the plan paid for it). All appreciation above that cost basis — the NUA — is taxed at long-term capital gains rates when you eventually sell, regardless of holding period.

Example: You have $500,000 of employer stock in your 401(k) with a $50,000 cost basis. If you roll it to a traditional IRA and convert to Roth, you pay ordinary income tax on the full $500,000 — roughly $160,000 at 32%. Under NUA, you distribute the stock to a taxable account, pay ordinary income tax on only $50,000 ($16,000), and the $450,000 of NUA is taxed at 15–20% long-term capital gains when sold — about $90,000 max. Total NUA tax: $106,000 versus $160,000 for conversion. That's a $54,000 savings, and the cost basis resets to market value at the NUA distribution date, so future appreciation after distribution is only capital gain.

When NUA Beats Roth Conversion — and When It Doesn't

NUA beats conversion when: the stock has appreciated at least 3–4x its cost basis, your marginal ordinary rate is significantly higher than your long-term capital gains rate, and you plan to sell the stock within 10–15 years (to crystallize the benefit). NUA loses to conversion when: the stock has little appreciation (the savings are trivial), you want tax-free compounding for multiple decades (Roth wins eventually), or you plan to hold the stock until death (step-up in basis via Section 1014 eliminates both strategies' advantage, but the Roth keeps building tax-free).

The Strict Eligibility Requirements

NUA has four non-negotiable requirements: (1) the distribution must be a “qualifying lump-sum distribution” — the entire plan balance distributed within one tax year following a triggering event (separation from service, death, disability, or reaching 59½); (2) employer stock is distributed in-kind, not cashed out; (3) the stock was held inside the 401(k) (not purchased after distribution); (4) no part of the plan is rolled over to an IRA before the lump-sum distribution — partial rollovers disqualify NUA treatment for any subsequent distribution. One misstep and the NUA opportunity is gone forever.

Estimated Tax Rules: Getting the Timing Right on a Conversion Year

A large Roth conversion creates an unusual tax bill that typical wage withholding won't cover. Underpaying triggers a Section 6654 underpayment penalty — not large in dollar terms but irritating in its avoidability.

Safe Harbor Math

You avoid the underpayment penalty by meeting any of three safe harbors during the tax year: (1) total tax payments equal 100% of your prior year's tax (110% if your prior-year AGI exceeded $150,000); (2) total tax payments equal 90% of your current year's tax; or (3) you owe less than $1,000 in total. For most moderate earners, the 100%/110% of prior year is easiest because you know the number with certainty. A conversion that roughly doubles your tax bill can be entirely covered by maintaining prior-year payment levels, with the shortfall paid with your April 15 return — no penalty.

Timing Within the Year

Estimated taxes are paid quarterly: April 15, June 15, September 15, and January 15 of the following year. The IRS uses an “annualized income installment method” for irregular income: if you convert in December, you can pay all the associated estimated tax with the January 15 (Q4) installment without penalty, provided you file Form 2210 Schedule AI to annualize. Conversely, conversions done earlier in the year require earlier estimated payments proportionally.

The Withholding Shortcut

Federal income tax withheld from any source (wages, IRA distributions, pension, Social Security) is treated as if paid evenly throughout the year, regardless of when it was actually withheld. A practical hack for conversion years: in December, take an IRA distribution (not a conversion) equal to the expected tax liability and elect 99% withholding — the IRS treats that December-withheld amount as if paid quarterly throughout the year. Redeposit the distribution to the IRA via a 60-day rollover to restore the principal, but keep the withheld amount as tax payment. This technique, while complex, can eliminate a Q1–Q3 underpayment retroactively. It uses your one-rollover-per-12-months allowance and requires meticulous execution.

Conversion Strategy for Estate Planning and Heirs

One of the most overlooked conversion benefits is estate planning. When you convert a Traditional IRA to Roth during your lifetime, you pay tax on the converted amount. But when you pass the Roth to your heirs, they inherit it tax-free—and under the SECURE Act's 10-year rule, they get 10 years of tax-free growth.

Example: You convert $200,000 from Traditional IRA to Roth, paying $50,000 in taxes. You pass away 5 years later, and your heirs inherit the Roth with $250,000 (after growth). They take distributions over the next 10 years. Every dollar they withdraw is tax-free. If they had inherited the Traditional IRA instead, each distribution would be ordinary income to them.

For a high-net-worth family, converting to Roth is a multi-generational wealth-transfer strategy. You pay tax now so your heirs never do. This is particularly valuable if you expect your children to be in higher tax brackets than you.