The board may set up a retirement account for the benefit of the employees and past employees of each utility. The board may provide for the method, manner, and amount of contributions by the utility out of its earnings, reserves, or earned surplus, and by employees if required by the plan, and may create an account for the utilities and allocate to the account contributions sufficient to establish the plan on a sound actuarial basis, including contributions for past services of employees. However, the plan may not require contributions from an employee to exceed six percent (6%) of his wage or salary.
IC 8-1.5-3-7