(1)    Except as authorized by other statutes, no person shall, directly or indirectly, contract for, take or receive in money, goods or things in action, or in any other way, any greater sum or any greater value, for the loan or forbearance of money, goods or things in action, than:

      (a)    At the rate of $12 upon $100 for one year computed upon the declining principal balance of the loan or forbearance;

      (b)    With respect to loans or forbearances repayable in substantially equal weekly or monthly installments and the face amounts of which include predetermined interest charges, at the rate of $6 upon $100 for one year computed upon that portion of the original principal amount of any such loan or forbearance, not including interest charges, for the time of such loan or forbearance, disregarding part payments and the dates thereof; and

      (c)    With respect to loans or forbearances repayable in installments other than of the type described in par. (b), the amount of interest may be predetermined at the rate set forth in par. (a) at the time the loan is made on the basis of the agreed rate of interest and the principal balances agreed to be outstanding and stated in the note or loan contract as an addition to the principal; provided that if any agreed balance of principal or principal and interest combined or any installment of principal or principal and interest combined is prepaid in full by cash or renewal the unearned interest shall be refunded as provided in sub. (2) (b). In the computation of interest upon any bond, note, or other instrument or agreement, interest shall not be compounded, nor shall the interest thereon be construed to bear interest, unless an agreement to that effect is clearly expressed in writing, and signed by the party to be charged therewith.

   (2)   Any loan for which the rate of interest charged exceeds $10 per $100 for one year computed upon the declining principal balance may be prepaid by the borrower at any time in whole or in part. Upon prepayment of any such loan in full by cash, renewal or refinancing, the borrower shall be entitled to a refund of unearned interest charged which shall be determined as follows:

      (a)    On any such loan which is repayable in substantially equal, successive installments at approximately equal intervals of time and the face amount of which includes predetermined interest charges, the amount of such refund shall be as great a proportion of the total interest charged as the sum of the balances scheduled to be outstanding during the full installment periods commencing with the installment date nearest the date of prepayment bears to the sum of the balances scheduled to be outstanding for all installment periods of the loan.

      (b)    On any other such loan, the amount of such refund shall not be less than the difference between the interest charged and interest, at the rate contracted for, computed upon the unpaid principal balances of the loan from time to time outstanding prior to prepayment in full.

   (3)   A contract to make loans or an evidence of indebtedness may provide for a rate of interest or penalty payable upon the principal amount of an extension of a loan or forbearance or upon any amount in default under a loan or forbearance which shall not exceed the rate allowed in sub. (1) (a).

   (4)   Any person making a loan for which interest is agreed to be paid at a rate exceeding the rate of $10 upon $100 for one year computed upon the declining principal of the loan shall, at or prior to making such loan, deliver to the borrower a statement, which may be incorporated in a copy of the evidence of indebtedness, setting forth all of the terms of the transaction in clear and distinct language, including:

      (a)    The rate of interest agreed upon in terms either of simple interest computed on the declining principal balance or of the actual interest cost in money, and

      (b)    A statement that the loan may be prepaid in full or in part and that, if the loan is prepaid in full, the borrower may receive a refund of interest charged.

   (5)   This section shall not apply to loans to corporations or limited liability companies.

   (6)   This section does not apply to transactions governed by chs. 421 to 427 and 429 or to discounts described in s. 422.201 (8).

   (7)   This section does not apply to any loan or forbearance in the amount of $150,000 or more made after May 26, 1978 unless secured by an encumbrance on a one- to four-family dwelling which the borrower uses as his or her principal place of residence. For the purposes of this section, a loan is deemed a loan which is in the amount of $150,000 or more if:

      (a)    The outstanding principal indebtedness under the loan initially exceeds $150,000; or

      (b)    The parties to the loan agree that the principal indebtedness may exceed $150,000 at some time during the term of the loan and, when the agreement was made, the principal indebtedness was reasonably expected to exceed $150,000 notwithstanding the fact that less than $150,000 in the aggregate was initially or later advanced.

   (8)   

      (a)    This section does not apply to any loan or forbearance which is made on or after April 6, 1980 and prior to November 1, 1981, or to any refinancing, renewal, extension, modification or prepayment on or after April 6, 1980 and prior to November 1, 1981, of any loan or forbearance, unless it is made by a federally chartered or state-chartered savings and loan association, except this section does apply to forbearances occurring primarily for personal, family or household purposes for which the only charge is a penalty or late charge for nonpayment when due.

      (b)    This section does not apply to loans made within 2 years after November 1, 1981, if made pursuant to loan commitments made on or after April 6, 1980 and prior to November 1, 1981, unless made by a federally chartered or state-chartered savings and loan association.

      (c)    This section does not apply to any loan or forbearance which is made on or after November 1, 1981, or to any refinancing, renewal, extension, modification or prepayment on or after November 1, 1981, of any loan or forbearance, except this section does apply to forbearances occurring primarily for personal, family or household purposes for which the only charge is a penalty or late charge for nonpayment when due.