Any such professional organization may adopt a pension, profit-sharing (whether cash or deferred), health and accident, insurance, or welfare plan for all or part of its employees including lay employees, provided that such plan does not require or result in the sharing of any specific or identifiable fees with lay employees and that any payments made to lay employees or into any such plan on behalf of lay employees are based upon their compensation or length of service or both rather than the amount of fees or income received.