Short answer. Yes. Once you have gone to court to enforce the written instrument, you can no longer turn around and ask for its reformation. The Civil Code treats the two as inconsistent positions, so filing the enforcement case is a choice that closes the door on correcting the document.
What the law says
When one of the parties has brought an action to enforce the instrument, he cannot subsequently ask for its reformation.
Civil Code, Article 1367 — Enforcement Bars Reformation. Read the full provision →
Suing on the document is itself a choice
Article 1367 of the Civil Code puts it without qualification: When one of the parties has brought an action to enforce the instrument, he cannot subsequently ask for its reformation. The bar is triggered by your own act. Nobody has to prove that you intended to abandon the remedy, and no separate waiver is needed. By asking a court to compel performance of the writing as it stands, you have told the court that the writing is the agreement — and the law holds you to that account of it afterwards, even if you later realise a clause was recorded wrongly.
What reformation is meant to do
Reformation is the remedy for a document that does not say what the parties actually agreed. The minds met, but the instrument failed to record the bargain because of mutual mistake, or because one side's fraud, inequitable conduct or the drafter's error crept in. The court does not make a new contract; it corrects the writing so that it reflects the true intention. That is why it presupposes a valid agreement — where there was never any real meeting of minds at all, reformation is not the remedy, and annulment or a declaration that no contract exists is what is in issue.
Why the two positions cannot stand together
Enforcement and reformation rest on opposite premises. To sue on the instrument is to affirm that it expresses the agreement; to ask for reformation is to say that it does not. Allowing both in sequence would let a party test the document first, then rewrite it when the result disappoints, with the other side forced to defend the same bargain twice. The rule also protects the record itself: written instruments are relied on by lenders, buyers and registries, and a party who has publicly stood on the text should not be able to unsettle it later at will.
What to do instead
The practical lesson is to decide before you file, not after. If you suspect the document misstates the deal, raise that at the outset — remedies can often be pleaded in the alternative in a single case, so the court is asked to correct the instrument and then enforce it as corrected. Read the article as a warning about sequence: it bars the party who has already sued on the writing, so the order in which you move matters more than most people expect. Actions for reformation are also subject to time limits, so gather the drafts, notes and correspondence showing the real agreement and take advice before any case is commenced.