Amends subparagraph (B) of 26 U.S.C. 250(a)(1) to replace the prior percentage and to redefine the deduction calculation to be 50 percent of the excess of (i) the sum of the global intangible low-taxed income amount included under section 951A and the section 78 amount attributable to it, over (ii) an amount equal to that sum times the round-tripping ratio (as determined under section 951A(b)(3)).

Modifies the formula used to determine net deemed intangible income return by replacing existing text and adding a clause requiring multiplication by the round‑tripping ratio.

Adds new paragraph (3) defining the 'round‑tripping ratio', how to calculate a shareholder's round‑tripped net CFC tested income, the foreign use rule reference, and an exception for certain small taxpayers.