Article 299 of Civil Code

Formal notice is unnecessary in the following cases: (a) If it is agreed that the debtor shall be considered in breach of the obligation merely by failing to perform it when it falls due. (b) If performance in kind of the obligation has become impossible or futile through the debtor's act. (c) If the subject matter of the obligation is compensation arising from an unlawful act. (d) If the subject matter of the obligation is delivery of a thing that the debtor knows to be stolen, or return of a thing that he received without entitlement while knowing this. (e) If the debtor declares in writing that he will not perform his obligation.