Ar cle 545 A creditor may assign his claim in whole or in part to a third person, except that: (1) a claim is not assignable by virtue of its nature; (2) a claim is not assignable as agreed by the par es; or (3) a claim is not assignable in accordance with law. Where the par es agree that a non-pecuniary claim may not be assigned, such agreement shall not be asserted against a bona de third person. Where the par es agree that a pecuniary claim may not be assigned, such agreement shall not be asserted against a third person. Ar cle 546 Where a creditor assigns his claim but fails to no fy the debtor thereof, the assignment is not e ec ve against the debtor. The no ce of the assignment of a claim may not be revoked, unless consented to by the assignee. Ar cle 547 Where a creditor assigns his claim, the assignee shall acquire the accessory right related to the claim, unless the accessory right belongs exclusively to the creditor. Failure to register the assignment of the accessory right or failure to change the possession thereof shall not a ect the acquisi on of the accessory right by the assignee. Ar cle 548 A er a debtor receives a no ce of assignment of a claim, the debtor’s defenses against the assignor may be asserted against the assignee. Ar cle 549 A debtor may claim a set-o against the assignee under any of the following circumstances: (1) when the debtor receives the no ce of assignment of a claim, the debtor has a claim against the assignor which becomes due prior to or at the same me of the due date of the assigned claim; or (2) the debtor’s claim and the assigned claim are generated on the basis of the same contract. Ar cle 550 The expenses for performance increased due to the assignment of a claim shall be borne by the assignor. Ar cle 551 Where a debtor delegates his obliga on in whole or in part to a third person, the consent of the creditor shall be obtained. The debtor or the third person may demand the creditor to give his consent within a reasonable period of me. Where the creditor makes no indica on, it shall be deemed as no consent given. Ar cle 552 Where a third person agrees with the debtor to join in the obliga on and no es the creditor thereof, or a third person indicates to the creditor his willingness to join in the obliga on, if the creditor fails to explicitly make a rejec on within a reasonable period of me, the creditor may request the third person to assume the joint and several obliga on with the debtor to the extent of the obliga on the third person is willing to assume. Ar cle 553 Where a debtor delegates his obliga on, the new debtor may assert a defense of the original debtor against the creditor; where the original debtor has a claim against the creditor, the new debtor may not claim a set-o against the creditor. Ar cle 554 Where a debtor delegates his obliga on, the new debtor shall assume the accessory obliga on related to the principal obliga on, unless the accessory obliga on belongs exclusively to the original debtor. Ar cle 555 A party may assign his rights and delegate his obliga ons under a contract to a third person with the consent of the other party. Ar cle 556 Where the rights and obliga ons under a contract are assigned and delegated together, the ti fi ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ff fi ti ti ti ti fi ti ff ti ft ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ff 61 ff ti Ar cle 544 Where the content of the contract that the par es agree to modify is not clear, it is presumed that the contract has not been modi ed.