(760 ILCS 15/4) (from Ch. 30, par. 504)
    Sec. 4. Income and Principal Defined. (a) Income is the return in money or property derived from the use of principal, including return received as:
    (1) rent of real or personal property, including sums received for cancellation or renewal of a lease;
    (2) interest received, including sums received as consideration for the privilege of prepayment of principal except as provided in Section 8 on premium and discount;
    (3) income earned during administration of a decedent's estate, as provided in Section 6;
    (4) corporate distributions, as provided in Section 7;
    (5) accrued increment on bonds or other obligations issued at discount, as provided in Section 8;
    (6) receipts from business and farming operations, as provided in Section 9;
    (7) receipts from disposition of natural resources, as provided in Sections 10 and 11.
    (b) Principal is the property which has been set aside by the owner or the person legally empowered so that it is held in trust eventually to be delivered to a remainderman, while the income is in the meantime taken or received by or held for accumulation for an income beneficiary. Principal includes:
    (1) consideration received by the trustee on the sale or other transfer of principal or on repayment of a loan or as a refund or replacement or change in the form of principal;
    (2) proceeds of property taken on eminent domain proceedings;
    (3) proceeds of insurance upon property forming part of the principal except proceeds of insurance upon a separate interest of an income beneficiary;
    (4) stock dividends, receipts on liquidation of a corporation and other corporate distributions, as provided in Section 7;
    (5) receipts from the disposition of bonds or other obligations, as provided in Section 8;
    (6) receipts from disposition of natural resources, as provided in Sections 10 and 11;
    (7) receipts from other principal subject to depletion, as provided in Section 12;
    (8) any profit resulting from any change in the form of principal;
    (9) any allowances for depreciation established under Section 9 and paragraph (2) of subsection (a) of Section 14;
    (10) receipts from the granting of options.
    (c) After determining income and principal in accordance with the terms of the instrument or this Act, the trustee shall charge to income or principal expenses and other charges as provided in Section 14.
(Source: P.A. 82-390.)