(iii) Exempt income. A foreign partner's allocable share of partnership ECTI does not include income or gain exempt from U.S. tax by reason of a provision of the Internal Revenue Code. A foreign partner's allocable share of partnership ECTI also does not include income or gain exempt from U.S. tax by operation of any U.S. income tax treaty or reciprocal agreement. In the case of income excluded by reason of a treaty provision, such income must be derived by a resident of an applicable treaty jurisdiction, the resident must be the beneficial owner of the item, and all other requirements for benefits under the treaty must be satisfied. The partnership must have received from the partner a valid withholding certificate, that is, Form W-8BEN (see 1.1446-1(c)(2)(iii) regarding when a Form W-8BEN is valid for purposes of this section), containing the information necessary to support the claim for treaty benefits required in the forms and instructions. In addition, for purposes of this section, the withholding certificate must contain the beneficial owner's taxpayer identification number.