Short answer. You made a counter-offer. The Civil Code requires acceptance to be absolute — an acceptance that changes any term of the offer is called a qualified acceptance and constitutes a counter-offer, not a contract. No contract was formed; the original offeror must now decide whether to accept your modified terms.
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. Acceptance made by letter or telegram does not bind the offerer except from the time it came to his knowledge. The contract, in such a case, is presumed to have been entered into in the place where the offer was made.
Civil Code, Article 1319 — Consent: Offer and Acceptance. Read the full provision →
Why acceptance must be absolute
Article 1319 of the Civil Code states that consent is formed by the meeting of the offer and the acceptance upon the thing and the cause which are to constitute the contract. It further provides that the offer must be certain and the acceptance absolute. A qualified acceptance constitutes a counter-offer. These requirements reflect a foundational principle of contract formation: the minds of the parties must genuinely meet on the same terms. An offeror puts forward a specific set of terms. The only response that closes a contract is an unconditional yes to all of those terms. Any modification, however small, means no contract was formed.
What happens when you change a term
When you accepted the offer but changed one of its terms, you did not accept — you made a counter-offer. Under Article 1319, a qualified acceptance is legally treated as a new offer from you to the original offeror. The original offer is no longer in play. The original offeror is now in the position you were in before: they can accept your counter-offer absolutely (forming a contract on your modified terms), reject it, or make another counter-offer. There is no contract between you and the original offeror at this point unless and until they accept your counter-offer without further modification.
What counts as a qualified acceptance
Any departure from the original offer's terms makes an acceptance qualified. This includes adding a new term, removing a term, modifying a price, changing the quantity, shortening or extending the delivery date, or adding a condition not found in the original offer. It does not matter whether the change seems minor or major — the legal effect is the same. Even a change in the method of payment or the time for performance converts the acceptance into a counter-offer. The doctrine does not rank modifications by significance; it simply asks whether the acceptance mirrors the offer exactly.
Acceptance by letter or telegram
Article 1319 also addresses acceptance sent by letter or telegram: such acceptance does not bind the offerer except from the time it came to his knowledge. This timing rule means the contract is not formed at the moment you send the letter but only when the other party actually receives and learns of the acceptance. The article also provides that in such cases, the contract is presumed to have been entered into in the place where the offer was made. For disputes about when a contract was formed and where it was entered into, these rules determine the answer.
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.
- Purificacion M. Vda. de Urbano, et al. vs. Government Service Insurance System (GSIS), et al, G.R. No. 137904, October 19, 2001 — read the decision on LawPhil →
- United Muslim and Christian Urban Poor Association, Inc., etc. vs. BRYC-V Development Corporation, etc., et al, G.R. No. 179653, July 31, 2009 — read the decision on LawPhil →
- Conchita Tan etc. vs. Planters Products Inc, G.R. No. 172239, March 28, 2008 — read the decision on LawPhil →
- Pedro Gonzales, et al. vs. Madame Pilar Farm Corp., et al, G.R. No. 115880, January 23, 2007 — read the decision on LawPhil →