(iv) Interest deductions. The rules of this paragraph (b)(3)(iv) shall apply for purposes of determining the amount of interest expense that is allocable to income which is (or is treated as) effectively connected with the conduct of a trade or business for purposes of calculating a foreign partner's allocable share of partnership ECTI. In the case of a non-corporate foreign partner, the rules of 1.8619T(e)(7) shall apply. In the case of a corporate foreign partner, the rules of 1.8825 shall apply by treating the partnership as a foreign corporation and using the partner's pro-rata share of the partnership's assets and liabilities for these purposes. For these purposes, the rules governing elections under 1.8825(a)(7) shall be made at the partnership level.