It is complicated because you looking at two different tax and legal systems and for tax you will also need to consider the interaction of the two. You could spend a lot money on advisors here and still come up with a cumbersome structure. My advise is to keep it simple and both keep your own U.S. and Irish companies as your income source. These companies can invoice whatever company you decide to work with whether it be Irish and the U.S. Perhaps a good starting point is to incorporate a company or companies where ever your customers or business are located. You can put you own structure behind that. My advise is keep is as simple as possible with as few moving parts as possible. If the business is big, or becomes big, talk to one of the larger accounting firms about a structure but the professional fees may be significant.