Backdoor Roth for Couples: The Lower-Earner Strategy

Quick Answer

Married couples where one spouse has substantially lower income can exploit that low-income year to convert traditional IRA balances to Roth at minimal tax cost. This works because conversions are taxed at the lower-earner's marginal rate. A spousal IRA conversion in a year the lower-earning spouse earns $30,000 costs far less tax than converting when both earn $150,000+.

The Married Filing Jointly Tax Advantage

Married couples filing jointly have wider tax brackets than single filers. In 2026:

A married couple can have up to $94,300 in taxable income and remain in the 12% bracket. Two single people would exceed the 12% bracket at $47,150 each.

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, their 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 standard deduction ($30,000 in 2026), taxable income is $135,000. They're in the 22% bracket.

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

With conversion: They can convert Tom's traditional IRA or their combined IRA to Roth. The conversion is taxed at their current marginal rate (22%). But by timing the conversion while Tom's income is low, they effectively "fill" the lower brackets at his low income rate.

Math:

• Taxable income: $135,000
• Space in 12% bracket: $94,300 – $135,000 = -$40,700 (overflowing)
• But wait—Tom earned only $15,000. If Tom has earned income, they can contribute to a spousal IRA and treat conversion as coming from Tom's income.
• Practical effect: Converting $40,000 costs them roughly $40,000 × 22% = $8,800 in tax (they're already in the 22% bracket).

But if Tom hadn't worked that year:

• Sarah earns $150,000, taxable income $135,000. She's in the 22% bracket.
• Converting $50,000 from her IRA costs $50,000 × 22% = $11,000 in tax.

The lower-earner year saves minimal tax here because both spouses' income combined puts them in the 22% bracket anyway. The real savings come when both spouses have low income.

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 standard deduction ($30,000), taxable income is $8,000—firmly in the 10% bracket!

If they have traditional IRA balances totaling $200,000, they can convert up to roughly $40,000 more and remain in the 10% bracket (filling the bracket up to $94,300).

Tax on $40,000 conversion at 10%: $4,000.

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

Over time, if they do this for multiple years before one resumes a high-paying job, they could convert $200,000 of traditional IRA to Roth at an average tax rate of 12%, costing $24,000 in tax. Without the strategy, converting the same $200,000 when earning $250,000+ costs at least $48,000–$56,000 in tax (24% federal + state taxes). Multi-year savings: $24,000–$32,000+.

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 higher-earning spouse can contribute to a spousal IRA in the lower-earning spouse's name. The lower earner controls this account. When the lower earner is in a low-income year, they can convert their spousal IRA to Roth at their own low tax rate.

Requirements:

• The lower-earning spouse must have earned income (wages or self-employment income).
• The higher-earning spouse can contribute up to the lower earner's earned income or $7,000 (2026 limit), whichever is less.
• Both spouses must consent to the strategy.

Example:

• Sarah earns $150,000. Tom earns $10,000.
• Sarah contributes $7,000 to a spousal IRA in Tom's name (using her earned income, allowed because they're married).
• Tom has $7,000 in his spousal IRA.
• Tom converts $7,000 of his spousal IRA to Roth.
• Tax: $7,000 × 10% bracket = $700 (since Tom is in the 10% bracket with his low income).

Over 5–10 years, Sarah could fund $35,000–$70,000 in spousal IRAs that Tom converts at low rates.

The Pro-Rata Rule Consideration

Spousal IRA conversions fall under the pro-rata rule. If Tom has a traditional IRA with $50,000 pre-tax money, and Sarah contributes $7,000 to a new spousal IRA that Tom will convert, the pro-rata ratio is:

• Total IRAs: $57,000
• Pre-tax: $50,000
• Pre-tax percentage: $50,000 / $57,000 = 87.7%
• Tom converts $7,000, but 87.7% × $7,000 = $6,140 is taxable.

To avoid this, Tom should have converted (or rolled over) his traditional IRA to a 401(k) before the spousal IRA contribution, removing pre-tax money from the IRA aggregation.

Many financial advisors recommend this sequencing:

1. Roll traditional IRA into 401(k) (if plan allows).
2. Contribute to spousal IRA.
3. Convert spousal IRA to Roth (now 0% taxable because the traditional IRA is in a 401(k), not aggregated).

Use the /products/lower-earner-roth-conversion-calculator tool to compute the pro-rata rule in your situation.

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. They transition to part-time consulting at $30,000/year. The lower earner was always part-time at $20,000/year. Combined income is $50,000. They convert $44,000 of traditional IRA to Roth annually for 10 years, totaling $440,000 converted at an average 12% rate = $52,800 in tax. Compared to converting at age 70 when Social Security pushes them into 22%+, the savings are $44,000+.

Scenario 3: One Spouse Has Rental Losses Tom owns rental properties with $30,000 in annual losses. His W-2 income is $80,000. His taxable income is $50,000. Sarah earns $150,000. Combined taxable income is $200,000. They're in the 22% bracket. But Tom could convert his spousal IRA to Roth at his low marginal rate (12%), saving 10 percentage points vs. converting at the married-combined rate (22%).

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.

The IRS scrutinizes Roth conversions of high earners, looking for abuses. Proper documentation protects you if audited.

When This Strategy Doesn't Help

1. Both spouses earn high income year-round: The lower-earner's income might still put them in the 22%+ bracket, reducing the conversion benefit.

2. High-income couple with large traditional IRAs: If Sarah earns $250,000 and Tom temporarily earns $20,000, converting Tom's share at 10% might seem good, but the couple's overall income is still $270,000 (24%+ brackets). The pro-rata rule might limit benefits if Sarah has large traditional IRAs.

3. State income tax: If you live in a high-tax state, the state tax on conversion might offset the federal savings. Consider relocating (e.g., moving to Florida or Texas before converting).

Sources

• Internal Revenue Service. "Spousal IRA Rules." IRS.gov.
• Internal Revenue Service. "Roth Conversion Pro-Rata Rule." IRS.gov.
• IRS Publication 590-A: Contributions to Individual Retirement Arrangements (IRAs).
• IRS Publication 590-B: Distributions from Individual Retirement Arrangements (IRAs).
• CFA Institute. "Tax Planning for Couples: Optimization Strategies."