Thanks for the quick reply.
I actually don't have an LLC altogether—still a sole-proprietorship but just applied for an EIN so I can create a Solo 401(k). I just wasn't sure if that meant that I now had to file two Schedule Cs and that income for SSN-based 1099s would have to be tracked separately from EIN-based 1099s—which would also impact how much I can contribute to the Solo 401(K).
Though it sounds like for my practical purposes the SSN and EIN would be rather interchangeable—I can open the Solo 401(k) with the EIN; I don't need to bother updating W9 forms with existing clients; and I can use the EIN on W9s moving forward for future clients.
