Except as provided in the Income Withholding for Child Support Act, every assignment of the wages or earnings of the head of a family and every contract or agreement intending or purporting to have the effect of such assignment shall be void unless such contract, agreement, assignment, or transfer is executed and acknowledged by both husband and wife in the same manner that conveyances of real estate are required to be signed and acknowledged by the laws of this state and shall be limited to a percentage of the wages of the head of household not greater than that subject to the operation of attachment, execution, and garnishee process as provided in section 25-1558. Nothing contained in this section shall be construed to void payroll deductions by the employer if such wages or earnings so deducted are for (1) purchase of government bonds, (2) contributions to charity, or (3) payment of employee organization dues, of group or individual insurance premiums, of pension assessments, to credit unions, or for a savings plan, in accordance with a written order of the employee which has been accepted by the employer. Every such assignment shall specify the employer who will pay the wages that are the subject of the assignment, and the assignment shall be valid only as to wages due from the employer or employers so specified. It shall be unlawful for any person, firm, corporation, company, partnership, limited liability company, or business institution to cause any employer by any such void assignment or by notice of any such void assignment to withhold the payment of any wages due the head of a family.