Payments under employers' plans on account of retirement, sickness or accident disability, medical or hospitalization expenses, or death

(a) The term “wages” does not include the amount of any payment (including any amount paid by an employer for insurance or annuities, or into a fund, to provide for any such payment) made to, or on behalf of, an employee or any of his dependents under a plan or system established by an employer which makes provision for his employees generally (or for his employees generally and their dependents) or for a class or classes of his employees (or for a class or classes of his employees and their dependents), on account of:

(1) An employee's retirement,

(2) Sickness or accident disability of an employee or any of his dependents,

(3) Medical or hospitalization expenses in connection with sickness or accident disability of an employee or any of his dependents, or

(4) Death of an employee or any of his dependents.

(b) The plan or system established by an employer need not provide for payments on account of all of the specified items, but such plan or system may provide for any one or more of such items. Payments for any one or more of such items under a plan or system established by an employer solely for the dependents of his employees are not within this exclusion from wages.