The foreign corporation owns 50% of the new US Corp that is starting in 2020, and all revenue is US-ECI , also the liabilities on the  FDAP will be withheld by the US Corp at the 5% based on the US Mexico treaty. The foreign corporation has already submitted w8-BEN-E to the us corporation. The 5472 will be filed by the US corporation with their 1120.

I had read that if a foreign corporation is claiming a reduction in taxes it must file a 1120f rather they owed taxes or not since their dividends is US-ECI?

Appreciate all feedback .