Sec. 4. (a) Except as provided in section 1(b) through 1(e) of this chapter, the commissioner shall maintain within the fund a separate experience account for each employer and shall credit to such account all contributions paid by such employer on its behalf except as otherwise provided in this article.
(b) The commissioner shall also maintain a separate account for each employer electing to make payments in lieu of contributions as provided in section 1(b) through 1(e) of this chapter and shall charge to such account all benefits chargeable to such employer and credit to such account all reimbursements made by such employer.