you have both the IRC sec 1367 and the various acts that confirm 1367(a) (1) (A) treatment under IRC 1366(a)(1)
(a)Determination of shareholder’s tax liability
(1)In general
In determining the tax under this chapter of a shareholder for the shareholder’s taxable year in which the taxable year of the S corporation ends (or for the final taxable year of a shareholder who dies, or of a trust or estate which terminates, before the end of the corporation’s taxable year), there shall be taken into account the shareholder’s pro rata share of the corporation’s—
(A)items of income (including tax-exempt income), loss, deduction, or credit the separate treatment of which could affect the liability for tax of any shareholder, and
