Our new multi-member LLC has only foreign founders and no one based in the U.S. Who can serve as partnership representative?

We are two founders from Spain and Portugal, and the LLC only became a partnership this year after we formalized shared ownership. None of us lives in the United States, and our accountant is also outside the U.S. We assumed the partnership representative would just be whichever founder signs the return, but now we are hearing about a substantial-presence requirement.

That sounds like more than a mailing address problem. If the IRS expects a U.S. street address, U.S. phone number, and someone available to meet in person in the U.S., our current plan may not work at all. We want to choose the role correctly before filing the first partnership return.