Yes, both spouses can each process a Mega Backdoor Roth Solo 401k conversion within the same Solo 401k plan, provided that both spouses are working in the same self-employed business and reporting earned self-employment income (e.g., each spouse has their own W-2 if the business is taxed as an S or C corporation, or their own Schedule C if taxed as a sole proprietorship or partnership).
Here’s how it works under a solo 401k plan:
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One Plan, One Fee: It will still be a single Solo 401k plan with one flat fee, even though both spouses are participating.
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Separate Accounts Required: Each spouse must have their own set of Solo 401k accounts under the name and EIN of the Solo 401k—for example, one account each for pre-tax, Roth, and voluntary after-tax (Mega Backdoor Roth).
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Voluntary After-Tax Contributions + In-Plan Roth Conversion: Each spouse can make voluntary after-tax contributions to their own after-tax Solo 401k account and then convert those funds to their own Roth Solo 401k account, which is what makes up the Mega Backdoor Roth strategy.
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Support for Both Participants: We are hands-on in helping both spouses open their individual accounts and complete any necessary paperwork, including the reporting for Roth conversions (e.g., preparing Form 1099-R as an optional free service when requested).
This setup allows each spouse to take full advantage of the Mega Backdoor Roth strategy under one unified plan—another reason our Solo 401k plan is popular with self-employed couples.
