158. An employer shall not deduct, for the purposes of this chapter, an amount which he pays to a trustee:(a) under a supplementary unemployment benefit plan, except to the extent allowed under section 964;
(b) under a deferred profit sharing plan, except to the extent provided in section 881;
(c) on behalf of his employees or those of a corporation with whom he does not deal at arm’s length under a profit sharing plan except to the extent provided for in section 856.