Cal. RTC § 18633

(a) (1) Every partnership, on or before the 15th day of the third month following the close of its taxable year, shall make a return for that taxable year, stating specifically the items of gross income and the deductions allowed by Part 10 (commencing with Section 17001). Except as otherwise provided in Section 18621.5, the return shall include the names, addresses, and taxpayer identification numbers of the persons, whether residents or nonresidents, who would be entitled to share in the net income if distributed and the amount of the distributive share of each person. The return shall contain or be verified by a written declaration that it is made under penalty of perjury, signed by one of the partners.

(2) In addition to returns required by paragraph (1), every limited partnership subject to the tax imposed by subdivision (b) of Section 17935, on or before the 15th day of the third month following the close of its taxable year, shall make a return for that taxable year, containing the information identified in paragraph (1). In the case of a limited partnership not doing business in this state, the Franchise Tax Board shall prescribe the manner and extent to which the information identified in paragraph (1) shall be included with the return required by this paragraph.

(b) Each partnership required to file a return under subdivision (a) for any taxable year shall (on or before the day on which the return for that taxable year was required to be filed) furnish to each person who is a partner or who holds an interest in that partnership as a nominee for another person at any time during that taxable year a copy of the information required to be shown on that return as may be required by regulations.

(c) Any person who holds an interest in a partnership as a nominee for another person shall do both of the following:

(1) Furnish to the partnership, in the manner prescribed by the Franchise Tax Board, the name, address, and taxpayer identification number of that other person, and any other information for that taxable year as the Franchise Tax Board may by form and regulation prescribe.

(2) Furnish to that other person, in the manner prescribed by the Franchise Tax Board, the information provided by that partnership under subdivision (b).

(d) The provisions of Section 6031(d) of the Internal Revenue Code, relating to the separate statement of items of unrelated business taxable income, shall apply.

(e) The provisions of Section 6031(f) of the Internal Revenue Code, relating to electing investment partnerships, shall apply, except as otherwise provided.

(f) The amendments made to this section by the act adding this subdivision shall apply to returns for taxable years beginning on or after January 1, 2016.