The IRS is going to consider both Solo401ks to be one plan, since you are spouses and considered related in the eyes of the IRS. This is the concept of “Controlled Group” in the US tax system.
If you have two entities of any kind, and you own both of them, then they are both one in the eyes of the IRS. The IRS views a married couple as one tax payer (hence, filing jointly). You and your spouse are the same person for tax purposes, and if you have one corporation and your spouse has another, the IRS will consider it to be one corporation. Thusly, if you and your spouse have two retirement accounts, the government can require that you treat it as one.
The Solo 401k can only have one business listed as the Adopting Employer. All of the funds contributed to the Solo 401k need to come from that one business. No outside funds can be contributed, even if you or your spouse runs another business.
What if you own one business that generates income and your spouse owns another?
If you and your spouse own separate businesses, then you have a few options moving forward:
Determine which business generates the most self-employment profit because that will provide for the largest contributions into your Solo 401k (and the largest tax benefits!) and use that company to sponsor the Solo 401k.
Aggregate the income from multiple businesses by forming a new entity such as an LLC, S-Corp or C-Corp, sometimes called a holding company.
Create a Controlled Group plan: Our team will lost both you and your spouse's business as adopting employers in the 401k plan. This allows you to each contribute money to your Solo 401k based on the income you're earning from each business. Please note there are additional fees to prepare a Controlled Group plan.
If you need to change the company you have listed as your Adopting Employer, please contact us to update your 401k plan documents.