26 U.S.C. § 61 : US Code - Section 61: Gross income defined

    (a) General definition
      Except as otherwise provided in this subtitle, gross income means
    all income from whatever source derived, including (but not limited
    to) the following items:
        (1) Compensation for services, including fees, commissions,
      fringe benefits, and similar items;
        (2) Gross income derived from business;
        (3) Gains derived from dealings in property;
        (4) Interest;
        (5) Rents;
        (6) Royalties;
        (7) Dividends;
        (8) Alimony and separate maintenance payments;
        (9) Annuities;
        (10) Income from life insurance and endowment contracts;
        (11) Pensions;
        (12) Income from discharge of indebtedness;
        (13) Distributive share of partnership gross income;
        (14) Income in respect of a decedent; and
        (15) Income from an interest in an estate or trust.
    (b) Cross references
          For items specifically included in gross income, see part II
        (sec. 71 and following). For items specifically excluded from
        gross income, see part III (sec. 101 and following).