It's 4% of worldwide revenue.
Legal concepts like "beneficial ownership" [1] and the definition of an "affiliate" under U.S. securities law [2] deal with this.
TL; DR When it comes to taxes, modern law isn't tricked by incorporated Russian dolls [3].
[1] https://en.wikipedia.org/wiki/Beneficial_ownership
If you're late to the party, which I think the majority businesses in and out of Europe are, means you have made other priorities.
Question is whether or not how hard they hit when GDPR goes live 25th of May. That remains to be seen, but it wouldn't surprise me if there's a `grace` period.