Article 1285

The debtor who has consented to the assignment of rights made by a creditor in favor of a third person, cannot set up against the assignee the compensation which would pertain to him against the assignor, unless the assignor was notified by the debtor at the time he gave his consent, that he reserved his right to the compensation.

If the creditor communicated the cession to him but the debtor did not consent thereto, the latter may set up the compensation of debts previous to the cession, but not of subsequent ones.

If the assignment is made without the knowledge of the debtor, he may set up the compensation of all credits prior to the same and also later ones until he had knowledge of the assignment. (1198a)