Short answer. You must manifest your intention to rescind — either by giving notice to the buyer or by some other overt act showing you are treating the transfer as undone. Article 1534 of the Civil Code does not require the buyer to receive that notice, but the lack of notice may be weighed against you.
What the law says
The transfer of title shall not be held to have been rescinded by an unpaid seller until he has manifested by notice to the buyer or by some other overt act an intention to rescind.
Civil Code, Article 1534 — Unpaid Seller's Right to Rescind. Read the full provision →
When the right to rescind arises
Article 1534 of the Civil Code gives an unpaid seller with a right of lien two grounds for rescinding the sale and reclaiming ownership. The first is a contractual reservation: if the contract of sale expressly stated that the seller may rescind in case of buyer default, that provision triggers here. The second is the ground relevant to most real-world disputes: the buyer has been in default in the payment of the price for an unreasonable time. What counts as unreasonable depends on the circumstances, including the nature of the goods, any credit terms agreed upon, and how long the seller waited.
How you actually exercise the rescission
The article specifies how rescission must be manifested: either by notice to the buyer or by some other overt act showing an intention to rescind. Rescission does not happen automatically just because the right exists. You must take a visible step. Notice to the buyer is the cleaner route — a written demand stating that you are treating the sale as rescinded and reclaiming ownership. An overt act is also sufficient, but it must clearly communicate the intention without any need for interpretation.
Notice not required to reach the buyer, but relevant
Article 1534 contains a nuance that matters practically. It says: It is not necessary that such overt act should be communicated to the buyer. So even if your notice was sent and never received, the overt act can still be effective. However, the giving or failure to give notice is explicitly described as relevant to any issue involving whether the buyer had been in default for an unreasonable time before the right of rescission was asserted. In plain terms: whether or not you notified the buyer, and when, can be used in court to assess the reasonableness of your timeline.
After rescission: what you can and cannot claim
Once the seller validly rescinds, the article draws a clean line on remedies. The seller is no longer liable to the buyer under the contract of sale. But the seller may recover damages from the buyer for any loss caused by the buyer's breach. So you are not limited to reclaiming the goods — you can also pursue compensation for the period of non-payment, loss of use, deterioration of the goods, or other losses the default caused. A lawyer can help you document these losses and choose the most effective way to recover them alongside the goods.