Should Married Couples Do a Roth Conversion in One Year? (w/Examples) + FAQs

This article reflects federal rules as of June 2026 and covers tax year 2025 (with a look ahead to 2026). State rules vary and are addressed in general terms below. Tax law changes — confirm current figures before you file.

Quick Answer

Usually no. For most married couples, spreading a Roth conversion across several years beats converting one big lump sum in a single year. A staged conversion keeps you in lower tax brackets and avoids Medicare and Social Security traps. A one-year conversion only wins in narrow cases.

A Roth conversion moves money from a pre-tax traditional IRA or 401(k) into a Roth account. You pay income tax on the amount you convert now, and in exchange that money grows tax-free and comes out tax-free later. The catch: a large one-year conversion can stack on top of your other income, push you into a higher tax bracket, raise your Medicare premiums two years later, and make more of your Social Security taxable.

The timing matters because the federal tax system is built in brackets and cliffs. Married couples filing jointly get wider brackets than singles, which gives you room to convert smartly — but only if you respect where the next bracket and the next surcharge begin. Roughly 42% of U.S. households own an IRA, and many retirees hold the bulk of their savings in pre-tax accounts that will be taxed at withdrawal, which is exactly why conversion timing is one of the most valuable retirement decisions you can make.

Here is what you will learn:

• 🧮 How to figure out whether one year or several years saves your household more tax.
• 📊 The federal brackets, Medicare (IRMAA) tiers, and Social Security thresholds that decide the answer.
• 👫 Three named-couple examples with the full dollar math worked out.
• ⚠️ The most common mistakes that turn a smart conversion into an expensive one.
• ✅ The exact steps, forms, and deadlines to convert correctly.

What a Roth Conversion Actually Is

A Roth conversion is a voluntary taxable event. You tell your IRA custodian to move some or all of your traditional (pre-tax) IRA into a Roth IRA. The converted amount is added to your ordinary income for that year, and you pay tax on it at your regular rates. There is no early-withdrawal penalty on a conversion, even if you are under 59½, because the money stays inside a retirement account.

The reason couples do this is to trade a known tax bill today for a zero tax bill later. Money inside a Roth IRA grows tax-free, comes out tax-free in retirement, and — unlike a traditional IRA — is not subject to required minimum distributions during the original owner’s lifetime, as the IRS confirms for Roth IRAs. That makes a Roth a powerful tool for controlling future taxable income and for leaving tax-free money to heirs.

The consequence of ignoring conversion planning is steep. If you leave a large traditional IRA untouched, required minimum distributions (RMDs) begin at age 73 under the SECURE 2.0 rules, and those forced withdrawals can push you into higher brackets for the rest of your life. A common misconception is that a conversion “saves taxes” by itself — it does not. It only wins if you convert at a lower rate than the rate you would otherwise pay later. What you should do is project your future RMDs and tax bracket before you convert a dollar.

Why “One Year vs. Many Years” Is the Whole Question

The federal income tax is progressive. Each layer of income is taxed at a higher rate than the last. When you dump a large conversion into a single year, the top slice of that conversion gets taxed at the highest bracket it reaches. Spreading the same total across several years keeps each year’s top slice in a lower bracket.

For tax year 2025, the married-filing-jointly brackets, per Fidelity’s published 2025 tables, run 10% up to $23,850, 12% up to $96,950, 22% up to $206,700, 24% up to $394,600, then 32%, 35%, and 37% above that. The jump from 24% to 32% is large, and the jump from 12% to 22% is the one most retirees try to manage. The consequence of crossing one of these lines with a lump-sum conversion is that you permanently pay the higher rate on that slice — money you never get back.

The misconception here is that “a bracket applies to all your income.” It does not — only the income inside each band is taxed at that band’s rate. What you should do is identify the top of the bracket you are comfortable filling and convert just enough each year to reach it, then stop.

Which Situation Applies to You?

The right answer depends on your stage of life and income. Find yourself below.

• You are 55–63, retired or semi-retired, before Social Security and RMDs. These are the “gap years,” and they are usually the best time to convert. Your taxable income is temporarily low, so you can fill the 12% and 22% brackets cheaply. Spreading across these years almost always beats one lump sum.
• You are 64–72, on Medicare or about to enroll. Now IRMAA (your Medicare premium surcharge) and the new senior deduction enter the math. A lump-sum conversion can spike your premiums two years later. Multi-year conversions that respect the IRMAA tiers usually win.
• You are 73 or older and taking RMDs. You must take your RMD first; you cannot convert your RMD. Conversions on top of RMDs add to already-high income, so smaller annual conversions are typical.
• You expect a single low-income year (job loss, business loss, a gap before a pension starts). This is the rare case where a larger one-year conversion can make sense, because you may never see a lower bracket again.
• You have a huge IRA and a short runway (for example, an older couple wanting to reduce a surviving spouse’s future “widow’s penalty”). A bigger one-year conversion can be worth the higher rate to avoid an even higher rate later.

The Three Traps a Lump-Sum Conversion Springs

A one-year conversion is rarely just about the income tax bracket. Three other systems pile on.

Trap 1 — Medicare IRMAA Surcharges

IRMAA stands for Income-Related Monthly Adjustment Amount. It is a surcharge added to your Medicare Part B and Part D premiums when your income is high. It uses your modified adjusted gross income (MAGI) from two years prior, so a 2025 conversion affects your 2027 premiums. As Forbes explains on IRMAA and conversions, IRMAA is a cliff: one dollar over a tier can cost a couple hundreds or thousands of dollars in extra premiums for a full year.

The consequence of blowing past an IRMAA tier with a lump-sum conversion is a surcharge that can reach over $400 per person per month at the top tiers — for two people, that is real money for twelve months. The misconception is that IRMAA phases in gradually; it does not — it jumps the instant you cross the line. What you should do is find the IRMAA tier you are under and keep your conversion below it.

Trap 2 — Social Security Taxation

If you have started Social Security, a conversion can make more of your benefits taxable. Up to 85% of benefits become taxable as your other income rises. As this advisory piece on Social Security and conversions notes, a conversion done after benefits begin can spike the taxable share of those benefits, creating a hidden “tax torpedo.”

The consequence is that each conversion dollar can effectively be taxed at a combined rate well above your stated bracket because it drags Social Security into taxation alongside it. The misconception is that Social Security is always tax-free — for many couples it is not. What you should do is, where possible, convert in the gap years before you claim Social Security.

Trap 3 — The New Senior Deduction Phase-Out

The One Big Beautiful Bill Act (OBBBA) created a new senior deduction of up to $6,000 per person age 65 or older, or up to $12,000 for a married couple where both qualify, per Thomson Reuters’ breakdown of the deduction. It applies to tax years 2025 through 2028 only and then sunsets — a critical date for planning.

Here is the trap: the deduction begins to phase out when MAGI exceeds $150,000 for joint filers and disappears completely at $250,000, reduced by 6% of every dollar over the threshold, as this CPA firm details on the senior deduction. A large one-year conversion can wipe out $12,000 of deductions for a 65-plus couple. The consequence is you lose a deduction worth real tax dollars on top of paying tax on the conversion. What you should do, if you are 65+, is size each year’s conversion to stay under or near $150,000 MAGI while the deduction lasts.

Worked Example 1 — The Bracket-Filling Couple

Meet Tom and Linda, both 60, retired early in Toronto-adjacent upstate New York. They have $600,000 in a traditional IRA and want it all in Roth before RMDs hit. Their only 2025 income is $40,000 from a small pension. After the 2025 married standard deduction of $30,000, their taxable income is $10,000.

If they convert the entire $600,000 in one year, their taxable income becomes roughly $610,000. The top slices get taxed at 35% and even 37%, and they would owe well over $160,000 in federal tax — an average rate far above where they need to be.

Instead, they spread it. Each year they convert up to the top of the 22% bracket. With $40,000 of pension income and the $30,000 standard deduction, they can convert about $196,700 and still land at the $206,700 top of the 22% bracket for 2025. Doing this for roughly three years moves the whole IRA at a blended rate near 18–20% instead of 30%-plus.

Conversion Approach	Result for Tom and Linda
Convert all $600,000 in 2025	Top dollars taxed at 35–37%; federal tax exceeds $160,000
Convert ~$196,700/year over 3 years	Top dollars capped at 22%; tens of thousands saved overall

Worked Example 2 — The IRMAA Cliff Couple

Meet Robert and Susan, both 67, on Medicare. Their MAGI before any conversion is $180,000. They want to convert $80,000.

If they convert the full $80,000 at once, their MAGI jumps to $260,000, crossing multiple IRMAA tiers. Two years later, both pay a higher Part B and Part D surcharge — for a couple, the extra premiums can run into the thousands for that year, as warned in the Forbes IRMAA analysis.

Conversion Approach	Two-Year-Later Medicare Cost
Convert $80,000 in one year	Jumps several IRMAA tiers; surcharge spikes for both spouses
Convert ~$26,000/year over 3 years, staying under the next tier	Surcharge stays flat or rises one small step

By splitting the conversion into three smaller pieces sized to stay below the next IRMAA threshold, they convert the same total while keeping premiums steady. The lesson: with Medicare in the picture, the tier line often matters more than the tax bracket.

Worked Example 3 — The Senior-Deduction Couple

Meet George and Maria, both 68, both eligible for the $6,000 senior deduction. Their baseline MAGI is $130,000. They are eligible for the full $12,000 combined senior deduction because they are under the $150,000 joint threshold, per the phase-out rules.

If they convert $90,000 in one year, MAGI rises to $220,000. That is $70,000 over the $150,000 threshold, so their deduction shrinks by 6% × $70,000 = $4,200 each, costing them $8,400 of the $12,000 deduction — gone in a single year.

Conversion Approach	Senior Deduction Outcome
Convert $90,000 in 2025 (MAGI $220,000)	Loses $8,400 of the $12,000 senior deduction
Convert ~$20,000/year, MAGI near $150,000	Keeps most or all of the $12,000 deduction each year through 2028

Because the deduction sunsets after 2028, George and Maria have a four-year window. Spreading modest conversions across 2025–2028 lets them harvest the deduction every year and convert their IRA gradually.

When a One-Year Conversion Actually Wins

Spreading is the default, but a single large conversion can be the smart move in specific cases.

• A one-time income crater. If a couple has a year with almost no income — a business loss, a job gap, a sabbatical — they may face a once-in-a-lifetime low bracket. Filling it aggressively, even into the 24% bracket, can beat waiting.
• A short time horizon before RMDs or a pension. If RMDs or a large pension start soon and will permanently push the couple into a high bracket, converting more now at 24% can beat converting later at 32%.
• Reducing the future “widow’s penalty.” When one spouse dies, the survivor files as single, with narrower brackets and lower IRMAA thresholds. A larger joint-year conversion now can prevent the survivor from facing much higher rates alone.
• Estate and legacy goals. Couples leaving IRAs to heirs in high tax brackets may convert more now so heirs inherit tax-free Roth money instead of a taxable IRA subject to the 10-year payout rule.

In each case, the principle is the same: convert more in one year only when your rate today is genuinely lower than the rate you or your heirs would otherwise pay later.

Federal vs. State: Does Your State Tax the Conversion?

Start with the federal rule: a conversion is fully taxable as ordinary federal income in the year you convert. Then ask the separate question of what your state does, because states do not automatically follow federal treatment.

Most states with an income tax treat a Roth conversion as taxable state income too, so you owe both. But the nine states with no broad income tax — including Florida, Texas, Tennessee, Nevada, Washington, Wyoming, South Dakota, Alaska, and New Hampshire (on wages) — do not tax the conversion at all. The consequence is large: a couple planning a move from a high-tax state to a no-tax state may want to wait and convert after they relocate. What you should do is confirm your specific state’s rule, and if a move is on the horizon, factor the timing into your conversion plan.

How to Report a Roth Conversion (Form 8606)

You report a Roth conversion on IRS Form 8606, filed with your Form 1040 for the conversion year. Your custodian will send you a Form 1099-R showing the distribution, and you reconcile it on your return.

• Part I captures any basis — nondeductible contributions you already paid tax on — so you are not taxed twice. The taxable portion flows through here, as outlined in these Form 8606 instructions.
• Part II, Lines 16–18 reports the conversion itself: the amount converted and the taxable amount.
• On Form 1040, the gross conversion shows on line 4a and the taxable amount on line 4b.

The consequence of skipping Form 8606 is that the IRS may tax your entire conversion even if part was already-taxed basis — you could pay tax twice. The good news, per this guidance on a missing Form 8606, is that there is no deadline to file a late 8606 to establish basis. What you should do is file Form 8606 every year you convert and keep the records permanently.

Deadlines, Timing, and Cost

The conversion deadline is firm: a conversion counts for the tax year in which the money actually moves, and that must happen by December 31 — there is no “prior year” conversion the way there is for IRA contributions. If you want a 2025 conversion, the funds must leave the traditional IRA by December 31, 2025.

If you are 73 or older, you must take your RMD first, before any conversion, because you cannot convert an RMD. Estimated taxes are also due: the extra income may require a fourth-quarter estimated payment by January 15 to avoid an underpayment penalty. As for cost, doing it yourself through your custodian is free, but a one-time conversion analysis from a CPA or fee-only advisor typically runs a few hundred to a couple thousand dollars — often worth it when six figures are on the table.

7 Mistakes Married Couples Make

• Converting the whole IRA in one year. The top slices get taxed at 32–37%, costing far more than a staged conversion at 22–24%.
• Paying the conversion tax from the IRA itself. This shrinks the amount that grows tax-free and, if under 59½, can trigger a 10% penalty on the withheld portion.
• Ignoring IRMAA. A conversion that crosses a Medicare tier raises premiums for both spouses two years later.
• Converting after claiming Social Security. This can make up to 85% of benefits taxable, inflating the real tax rate on the conversion.
• Forgetting the senior deduction phase-out. A 65-plus couple over $150,000 MAGI loses 6% of the deduction per dollar, up to the full $12,000.
• Skipping estimated taxes. A large conversion without a Q4 estimated payment can trigger underpayment penalties.
• Not filing Form 8606. Without it, already-taxed basis can be taxed a second time.

Do’s and Don’ts

• Do project your future RMDs first — they reveal whether you will be in a higher bracket later, which is the whole reason to convert now.
• Do convert in the gap years — the window between retirement and Social Security/RMDs usually offers the lowest brackets of your life.
• Do pay the tax from outside money — using a taxable account keeps the full conversion growing tax-free.
• Do watch the IRMAA tiers — staying one dollar under a tier protects two years of Medicare premiums.
• Do recheck the math each December — your year-end income determines exactly how much room you have left.
• Don’t convert blindly to a round number — convert to a bracket or tier line, not an arbitrary dollar amount.
• Don’t ignore the surviving-spouse rate — single brackets are narrower, so plan for the widow’s penalty.
• Don’t convert your RMD — it is not allowed if you are 73 or older; take the RMD first.
• Don’t forget the 2028 sunset — the senior deduction and other OBBBA breaks expire, so use them while they last.
• Don’t go it alone with a large IRA — a professional projection often pays for itself many times over.

Pros and Cons of a One-Year Conversion

• Pro: Simplicity. One conversion, one tax bill, done — no multi-year tracking.
• Pro: Locks in today’s rates. If you expect tax rates to rise, you pay at known rates now.
• Pro: Maximizes time in the Roth. The full amount starts growing tax-free immediately.
• Pro: Helps in a low-income year. A one-time income crater can be filled cheaply.
• Pro: Reduces the widow’s penalty fast. It shrinks the survivor’s future taxable IRA quickly.
• Con: Bracket creep. Top slices can hit 32–37%, far above a staged rate.
• Con: IRMAA spike. A single big year can raise both spouses’ Medicare premiums.
• Con: Social Security torpedo. It can make up to 85% of benefits taxable.
• Con: Lost senior deduction. A 65-plus couple can lose the full $12,000 deduction.
• Con: No do-over. Since 2018, conversions cannot be undone (recharacterized), so a mistake is permanent.

What to Do Next

1. Pull your numbers. Gather your traditional IRA balances, expected income, ages, and Social Security/RMD start dates.
2. Project your future bracket. Estimate RMDs at 73 to see if your future rate is higher than today’s.
3. Pick your ceiling. Choose the bracket top, IRMAA tier, or $150,000 senior-deduction threshold you will not cross.
4. Size the annual conversion. Subtract your other income and standard deduction from that ceiling to find your conversion room.
5. Execute by December 31. Instruct your custodian, pay any Q4 estimated tax by January 15, and pay the tax from outside funds.
6. File Form 8606. Report the conversion and keep records permanently.
7. Call a pro if it is complex. With six-figure IRAs, IRMAA, Social Security, or a surviving-spouse plan in play, a CPA or fee-only advisor is worth the fee.

This article is educational and is not a substitute for personalized advice from a licensed CPA, tax attorney, or financial advisor for your specific situation.

FAQs

Can married couples convert from each other’s IRAs in the same year? Yes. Each spouse converts from their own IRA — there are no joint IRAs. But both conversions land on the same joint return, so their combined total drives your bracket, IRMAA, and senior-deduction phase-out for tax year 2025.

Is there a limit on how much you can convert in one year? No dollar limit. You can convert any amount, even your entire traditional IRA, in a single year. The only “limit” is practical — the tax bracket, IRMAA tier, and deductions you are willing to cross.

Can you undo a Roth conversion if you convert too much? No. Recharacterizing (reversing) a conversion has been banned since 2018. Once you convert, it is permanent for that tax year, which is why sizing it correctly the first time matters.

Does a Roth conversion count as income for Medicare IRMAA? Yes. A conversion raises your MAGI, and IRMAA uses MAGI from two years prior. A 2025 conversion can raise your 2027 Medicare Part B and Part D premiums if it crosses a tier.

Do we have to take our RMD before converting? Yes, if you are 73 or older. You must take your required minimum distribution first; an RMD cannot be converted to a Roth. You may convert additional amounts after the RMD is satisfied.

Can a married couple claim two senior deductions? Up to $12,000. If both spouses are 65 or older and file jointly, each may claim up to $6,000 for tax years 2025 through 2028, subject to the $150,000–$250,000 MAGI phase-out.

Does converting increase how much of our Social Security is taxed? Yes. A conversion raises your income, which can push up to 85% of your Social Security benefits into taxable territory, raising your effective rate on the conversion.

When is the deadline to do a 2025 conversion? December 31, 2025. Conversions count for the year the money actually moves. Unlike IRA contributions, there is no prior-year deadline extending into April.

What form reports a Roth conversion? Form 8606. You file it with your Form 1040 for the conversion year, reporting the conversion in Part II and reconciling it against the Form 1099-R from your custodian.

Should we pay the conversion tax from the IRA? No. Pay the tax from a taxable account when possible. Using IRA money shrinks your tax-free balance and, if you are under 59½, the withheld amount can face a 10% penalty.

Does our state tax a Roth conversion? It depends. Most income-tax states tax the conversion as state income, but nine no-income-tax states do not. Confirm your state’s rule, especially if you plan to relocate before converting.

Is one year ever better than spreading it out? Yes, sometimes. A one-time low-income year, a short runway before RMDs, or a plan to reduce a surviving spouse’s future taxes can all justify a larger single-year conversion.

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