(a) In general. A partner's distributive share of partnership gross income (under section 702(c)) constitutes gross income to him. Income in respect of a decedent (under section 691) constitutes gross income to the recipient. Income from an interest in an estate or trust constitutes gross income under the detailed rules of Part I (section 641 and following), Subchapter J, Chapter 1 of the Code. In many cases, these sections also determine who is to include in his gross income the income from an estate or trust.

(b) Creation of sinking fund by corporation. If a corporation, for the sole purpose of securing the payment of its bonds or other indebtedness, places property in trust or sets aside certain amounts in a sinking fund under the control of a trustee who may be authorized to invest and reinvest such sums from time to time, the property or fund thus set aside by the corporation and held by the trustee is an asset of the corporation, and any gain arising therefrom is income of the corporation and shall be included as such in its gross income.