Short answer. At the moment a certain offer meets an absolute acceptance on the same thing and the same cause. Nothing else is needed — not a signature, not a down payment, not delivery. Where the acceptance is sent by letter or telegram, it binds the offerer only once it reaches his knowledge.

What the law says

Consent is manifested by the meeting of the offer and the acceptance upon the thing and the cause which are to constitute the contract. The offer must be certain and the acceptance absolute. A qualified acceptance constitutes a counter-offer.

Civil Code, Article 1319 — Consent: Offer and Acceptance. Read the full provision →

What the law says

Acceptance made by letter or telegram does not bind the offerer except from the time it came to his knowledge.

Civil Code, Article 1319 — Consent: Offer and Acceptance. Read the full provision →

Perfection is a moment, not a document

Article 1319 of the Civil Code locates consent precisely: it is manifested by the meeting of the offer and the acceptance upon the thing and the cause which are to constitute the contract. Once those two meet, the contract exists and both sides are bound, even if nobody has signed anything and nothing has yet been handed over. The written deed that follows records the agreement; it does not create it. This is why a party who says "we never signed" is often answering the wrong question. What matters is whether an offer was accepted, and when.

"Certain" and "absolute" are strict words

The article requires that the offer must be certain and the acceptance absolute. An offer is certain when it states enough that a simple yes completes the bargain — the thing and the price, at minimum. A proposal to sell "at a reasonable figure to be agreed" leaves the essential term open and cannot be accepted into a contract. Acceptance is absolute when it adds nothing and changes nothing. Agreement in principle, subject to conditions, is not acceptance, and neither is a yes that quietly moves the delivery date.

A changed reply flips who is bound

The sentence that surprises people most is that A qualified acceptance constitutes a counter-offer. Reply to an offer with a lower price and you have not accepted at a lower price — you have destroyed the original offer and made a new one of your own. The other side is now free to walk away, and you are the one who can be taken up. Negotiations that go back and forth by message are full of these reversals, and the party who assumes the first offer is still on the table can find it is no longer available at all.

Acceptance at a distance, and where the contract is made

Where the parties are not face to face, Article 1319 fixes the timing: Acceptance made by letter or telegram does not bind the offerer except from the time it came to his knowledge. So the offerer is not caught by an acceptance still in transit, and an offer withdrawn before that acceptance is known to him does not ripen into a contract. The same provision presumes the contract was entered into where the offer was made. If you are trying to establish that a deal was struck, the useful evidence is therefore dated: what was offered, what was said back, and when the reply actually reached the other side.

Cases citing this provision

These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.

Related provisions

Note. Statute text quoted on this page is reproduced from the official enactment and is linked to the full provision. The explanation around it is general legal information from Vivas & Nobles Law Office, not legal advice. Whether it applies to your situation depends on facts only a lawyer reviewing them can assess.