Backdoor Roth for Couples: The Lower-Earner Strategy

The Married Filing Jointly Tax Advantage

Married couples filing jointly have wider tax brackets than single filers. For 2026 (Rev. Proc. 2025-32):

Through the 22% band the joint thresholds are exactly double the single ones, so there is no marriage penalty to work around here — a married couple can hold up to $100,800 in taxable income and remain in the 12% bracket, where two single filers would each be capped at $50,400.

When one spouse earns substantially more than the other, their combined income might push into higher brackets. But if one spouse is temporarily unemployed, between jobs, or taking a career break, the household's low income that year creates a "conversion opportunity."

The Lower-Earner Roth Conversion Strategy

Scenario: Sarah earns $150,000 (marketing exec). Her husband Tom takes a sabbatical and earns $15,000 (part-time consulting).

Married filing jointly, their combined income is $165,000. After the 2026 standard deduction of $32,200, taxable income is $132,800. They're in the 22% bracket.

Without conversion: Any additional income (bonus, investment gains) is taxed at 22%.

With conversion: They can convert either spouse's traditional IRA. Either way the conversion lands on the same joint return, on top of the same $132,800, and is taxed at the same 22%.

Math:

• Taxable income: $132,800
• Room left in the 12% bracket: $100,800 − $132,800 = −$32,000. They are already $32,000 past it
• Converting $40,000 takes them to $172,800, still inside the 22% band (which runs to $211,400), so the cost is $40,000 × 22% = $8,800

But if Tom hadn't worked at all that year:

• Combined income $150,000, taxable income $117,800. Still the 22% bracket
• Converting $50,000 takes them to $167,800 — still inside the band — so it costs $50,000 × 22% = $11,000

Tom's sabbatical saved them almost nothing, and here is the reason: a joint return has one set of brackets, not one per spouse. Sarah's $150,000 fills the low brackets before Tom's income is even reached, so a conversion always sits on top of the pile at the household's top marginal rate. Whose IRA it comes out of is irrelevant to the tax. The real savings come only when the combined income is low.

Maximum Savings: Both Spouses Have Low Income

Scenario: Sarah and Tom both quit their jobs at year-end. For next year (2026), they plan to travel and live modestly. Sarah earns $20,000 from freelance work. Tom earns $18,000 from consulting. Combined income: $38,000.

After the 2026 standard deduction of $32,200, taxable income is $5,800 — firmly in the 10% bracket.

They now have two different ceilings to aim at, and confusing them is the usual mistake:

• Stay entirely in the 10% bracket: room to the top of that band is $24,800 − $5,800 = $19,000. Tax on a $19,000 conversion: $1,900.
• Fill the 12% bracket: room to $100,800 is $95,000. Tax: $19,000 at 10% ($1,900) plus $76,000 at 12% ($9,120) = $11,020, a blended rate of 11.6%.

The second is almost always the better move. Twelve percent on retirement money is close to the cheapest rate available to anyone in the United States, and a bracket left unfilled this year cannot be carried forward.

Tax on a $40,000 conversion: $19,000 at 10% + $21,000 at 12% = $4,420 — a blended 11.1%.

Compare to a normal high-income year where the same $40,000 conversion at 24% would cost $9,600. Savings: $5,180.

Over time, if they do this for several years before one resumes a high-paying job, they could convert $200,000 of traditional IRA to Roth at a blended rate near 12%, costing roughly $24,000 in tax. Converting the same $200,000 in a year they earn $250,000 puts most of it in the 24% band and some in the 32% band — around $49,000 in federal tax alone, before any state tax. Multi-year savings: $25,000+.

Spousal IRA Transfers and Rollovers

Under the "spousal rollover" rules, a spouse can inherit an IRA upon the other spouse's death and roll it over into their own IRA. But during life, direct transfers between spouses are not allowed.

However, there's a workaround: the Kay Bailey Hutchison spousal IRA (IRC §219(c), described in IRS Publication 590-A). The higher-earning spouse's compensation can fund an IRA in the lower-earning spouse's name, and the lower earner owns and controls that account.

Requirements — note the first one, which is the opposite of what most people assume:

• The lower-earning spouse does not need earned income of their own. That is the entire point of the provision. What matters is the couple's combined taxable compensation, which must at least cover both contributions.
• You must file a joint return. Married filing separately disqualifies you.
• Each spouse may contribute up to $7,500 for 2026, or $8,600 if 50 or older — so $15,000 or $17,200 between them.
• Each spouse needs a separate IRA in their own name.

Example:

• Sarah earns $150,000. Tom earns nothing.
• Sarah's compensation supports a $7,500 contribution to an IRA in Tom's name, alongside $7,500 in her own.
• Tom now owns $7,500 in a traditional IRA that he can convert.

Over 5–10 years this funds $37,500–$75,000 of IRA money in Tom's name. Be clear about what that does and does not buy, though. It does not get the conversion taxed at a lower rate — a joint return has one set of brackets, so a conversion from Tom's IRA is taxed exactly like one from Sarah's. What it buys is control of the pro-rata calculation, which genuinely is measured per person.

The Pro-Rata Rule Consideration

Spousal IRA conversions fall under the pro-rata rule, and this is the one place where whose IRA it is genuinely changes the answer — aggregation is measured per person, not per household. Sarah's IRA balances have no effect on Tom's conversion, and his have no effect on hers.

If Tom has a traditional IRA holding $50,000 of pre-tax money, and $7,500 goes into a new spousal IRA that he will convert:

• Total of Tom's traditional, SEP and SIMPLE IRAs: $57,500
• Pre-tax portion: $50,000
• Pre-tax percentage: $50,000 / $57,500 = 87.0%
• Tom converts $7,500, but 87.0% × $7,500 = $6,522 of it is taxable

Note also that the ratio is measured on the balance at 31 December of the conversion year, not on the day you convert — so a rollover that lands in the account in November still spoils a conversion done in March.

To avoid this, Tom should roll his traditional IRA into a 401(k) before the spousal IRA contribution, removing pre-tax money from his personal aggregation.

Many financial advisors recommend this sequencing:

1. Roll traditional IRA into 401(k) (if a plan will accept it).
2. Contribute to the spousal IRA.
3. Convert to Roth — now 0% taxable, because the pre-tax money sits in a 401(k) and 401(k)s are not part of the IRA aggregation.

This is exactly the arithmetic worth running before you move anything: the Roth conversion calculator will apply the pro-rata fraction to your own balances and show the taxable portion of a conversion at a given size.

Real-World Scenarios

Scenario 1: Sabbatical Year One spouse takes a year off for grad school, family care, or travel. Their income is $0 or minimal. The couple converts $50,000–$100,000 of IRA to Roth at low rates, then resumes normal income next year.

Scenario 2: Early Retirement / Semi-Retirement The higher earner retires at 55 and moves to part-time consulting at $30,000. The other spouse was always part-time at $20,000. Combined income $50,000, minus the $32,200 standard deduction, leaves $17,800 of taxable income. Room to the top of the 12% band is $83,000 — and that is the number to aim at, not the $44,000 most people convert out of caution. Converting $44,000 a year costs $700 at 10% plus $4,440 at 12% = $5,140, a blended 11.7%. Over ten years that is $440,000 converted for about $51,400 of tax. The same $440,000 converted after 73, when required minimum distributions and Social Security have pushed them to 22%, would cost about $96,800. Savings: roughly $45,000 — and that is before counting the reduction in future RMDs and in the share of Social Security that becomes taxable.

Scenario 3: The Year a Rental Property Is Sold This one is worth stating carefully, because the obvious version does not work. Tom owns rentals throwing off $30,000 of annual losses while the couple's combined income is $230,000. Those losses do not create a conversion window: the $25,000 special allowance under §469(i) phases out between $100,000 and $150,000 of MAGI and is entirely gone at their income, so the losses are suspended, not deducted. Their taxable income is unchanged and a conversion would still be taxed at 22% or 24%.

The window opens on the day he sells the property. A fully taxable disposition of a passive activity releases the entire suspended loss against ordinary income under §469(g). Several years of $30,000 losses released at once can be a six-figure deduction landing in a single year — which drops taxable income far enough to make that the cheapest conversion year the couple will ever have. The move is to plan the sale and the conversion together, in the same tax year, rather than discovering the opportunity the following April.

Timing and Documentation

Document the strategy in writing. Keep records of:

• Spousal IRA contributions (Form 5498).
• Conversions (Form 8606).
• Correspondence with the financial institution requesting the conversion.

These are not optional. The custodian files Form 5498 for the contribution and Form 1099-R for the conversion, and the IRS matches both against the Form 8606 on your return. A missing 8606 means the IRS sees a fully taxable distribution and bills you for it — and because basis is cumulative, an omission in one year keeps costing you in every later year until you correct it.

When This Strategy Doesn't Help

1. Both spouses earn well year-round: if combined taxable income never drops below $100,800, there is no cheap bracket to fill and the conversion is simply taxed at 22% or 24%. That can still be worth doing as a hedge against higher future rates, but it is not this strategy.

2. One spouse's income drops but the household's does not: if Sarah earns $250,000 and Tom's income falls from $80,000 to $20,000, combined income is still $270,000 and every converted dollar lands in the 24% band. There is no lower rate hiding in Tom's IRA. The only thing his account gives you is a clean pro-rata calculation — and only if his traditional, SEP and SIMPLE balances are near zero. Sarah's balances are irrelevant to his conversion, and his to hers.

3. State income tax: in a high-tax state the state bill can swallow much of the federal saving, and a handful of states tax conversions that the federal system would not. Moving is a real option for a retiree, but it requires a genuine change of domicile before the conversion — not a mailing address — and states with departing high earners audit this closely.

4. You would have to pay the tax out of the IRA: see the FAQ. Paying conversion tax with converted money is what turns a good strategy into a mediocre one.

FAQ

Q: Can we convert from my lower-earning spouse's IRA and have it taxed at their lower rate? A: No, and this is the most common misunderstanding about the strategy. A joint return pools all income and applies one set of brackets, so a conversion from either spouse's IRA sits on top of the same taxable income and is taxed at the same marginal rate. What creates the saving is the household's low income in that particular year, not the ownership of the account. Ownership matters for exactly one thing — the pro-rata rule, which is calculated per person — so if one spouse has a clean IRA and the other has a $200,000 rollover, convert from the clean one.

Q: How should we pay the tax on the conversion? A: From taxable savings outside the IRA, always. If you withhold the tax from the conversion itself and either of you is under 59½, the withheld amount is treated as a distribution rather than a conversion: it is taxed, hit with the 10% early-distribution penalty, and never reaches the Roth. On a $95,000 conversion with $11,020 of tax, paying from the IRA costs an extra $1,102 in penalty and permanently removes $11,020 from tax-free compounding. If you cannot cover the tax from outside cash, convert a smaller amount instead.

Q: If our income turns out higher than expected, can we undo the conversion? A: No. The Tax Cuts and Jobs Act repealed the recharacterisation of Roth conversions effective 2018, and OBBBA did not restore it. You can still recharacterise a contribution, but a conversion is permanent the moment it settles. The practical consequence is scheduling: convert in December, when the year's income, bonuses and capital gains are known, rather than in January on an estimate. Convert in two or three tranches through the autumn if you want to fine-tune the amount as the picture firms up.

Q: Does conversion income affect anything besides our tax bracket? A: Yes, and this is where the strategy quietly gets expensive. Conversion income raises MAGI, which can cost an early-retired couple their Affordable Care Act premium tax credits outright — often a larger number than the tax saving itself. It can also trigger Medicare IRMAA surcharges two years later: for 2026 the first tier starts at $218,000 of MAGI for joint filers, on top of the standard Part B premium of $202.90 a month. It can pull more of your Social Security into taxable income, and it starts a separate five-year clock on each converted amount for anyone under 59½. Before a large conversion in your early sixties, check the surcharge with the IRMAA calculator — the lookback means a conversion at 63 shows up on your Medicare premium at 65.

Sources

• Internal Revenue Service. Revenue Procedure 2025-32 — the 2026 bracket thresholds and standard deduction used throughout.
• Internal Revenue Code §219(c) — the Kay Bailey Hutchison spousal IRA limit; explained in IRS Publication 590-A.
• Internal Revenue Code §408(d)(2) — the aggregation rule behind the pro-rata calculation, reported on Form 8606.
• Internal Revenue Code §469(i) and §469(g) — the passive activity loss allowance and phase-out, and the release of suspended losses on a taxable disposition.
• IRS Publication 590-A: Contributions to Individual Retirement Arrangements (IRAs).
• IRS Publication 590-B: Distributions from Individual Retirement Arrangements (IRAs).