In addition to any other powers and duties, any school district or educational service district may contract with any classified or certificated employee to defer a portion of that employee's income, which deferred portion shall in no event exceed the appropriate internal revenue service exclusion allowance for such plans, and shall subsequently with the consent of the employee, deposit or invest in a credit union, savings and loan association, bank, mutual savings bank, or purchase life insurance, shares of an investment company, or a fixed and/or variable annuity contract, for the purpose of funding a deferred compensation program for the employee, from any life underwriter or registered representative duly licensed by this state who represents an insurance company or an investment company licensed to contract business in this state. In no event shall the total investments or payments, and the employee's nondeferred income for any year exceed the total annual salary, or compensation under the existing salary schedule or classification plan applicable to such employee in such year. Any income deferred under such a plan shall continue to be included as regular compensation, for the purpose of computing the retirement and pension benefits earned by any employee, but any sum so deducted shall not be included in the computation of any taxes withheld on behalf of any such employee.