FEA vs FES in Chile: when the law requires an advanced electronic signature (and what happens if you get it wrong)

The document you signed may be worth nothing

A municipality issues a resolution, signs it with a “signer” tool it bought on its own, and serves notice. Months later, someone challenges it. The argument isn’t about the merits: it’s that the signature doesn’t prove authorship with the force the law requires for that act. The resolution is left hanging — and so is everything built on top of it.

This isn’t hypothetical: it’s the most common and most expensive mistake around electronic signatures in Chile, and it almost always comes from confusing two things that look alike but aren’t the same: the simple electronic signature (FES) and the advanced electronic signature (FEA).

This article is for the IT lead of a public agency or municipality, for the vendor that builds software for the State, and for any company that signs important contracts digitally. The goal isn’t to turn you into a lawyer — it’s that you know, before signing, when the law forces you to use FEA, because getting it wrong isn’t a detail: it voids the act.

The difference that matters isn’t technical, it’s evidentiary

Almost every guide starts by explaining that FES is “a typed name or a checkbox” and FEA is “a signature with a certificate.” That’s correct, but it falls short. The difference that actually affects you shows up the day someone disputes the document.

Simple Electronic Signature (FES). Any electronic data that identifies the signer: a name at the bottom of an email, an image of a handwritten signature, an “I accept” click. It has legal validity among those who accept it. But it carries no presumption: if someone questions it, whoever presented it has to prove that the person actually signed and that the document wasn’t altered.

Advanced Electronic Signature (FEA). The one created with a certificate issued by a provider accredited by the Accreditation Entity of the Ministry of Economy. The Law 19,799 gives it the same legal force as a handwritten signature, and with it the document enjoys a presumption of authorship and integrity: it is assumed true that the person signed and that nothing was modified, unless the other side proves otherwise.

That’s the whole thing. With FES, the burden of proof is on you. With FEA, the burden is on whoever wants to deny it. In a trial, an audit or a regulatory review, that difference decides who wins.

When the law forces you to use FEA (it’s not optional)

There are acts where FES simply doesn’t work, because the law expressly requires an advanced signature. The main ones:

• Electronic public instruments. A copy of a public deed, a Civil Registry certificate, a resolution that produces the effects of a public instrument: they are authenticated with the issuer’s FEA.
• Formal administrative acts of the State. When the act produces effects that require the formality of a public instrument or deed, the signature must be advanced. Law 19,799 says so, and the Law 21,180 reinforces it.
• Electronic judicial mandates. A power of attorney granted electronically must incorporate the FEA of whoever issues it.
• Incorporation, amendment and dissolution of companies. The forms of the Registry of Companies and Partnerships are signed with FEA.

For everything else — an agreement between private parties, a consent, an internal annex — FES may be enough, as long as the parties accept it and no one later demands a higher standard. The right question is never “which signature do I want to use?” but “which signature does thisprocedure require?” You can check the official sheet for each case at ChileAtiende.

The State’s case: why signing wrong is a void act

In the public sector the margin for error is smaller, because the signature is tied to the validity of the act. Law 21,180 requires every organ of the State Administration to process its procedures in electronic format, with a hard deadline of December 31, 2027, with no possible extension. And in that electronic world, every act that used to be signed by hand on paper is now signed with FEA.

Institutional FEA is channeled mainly through FirmaGob, the Digital Government Secretariat’s platform where authorized officials sign with their certificate. If an agency digitizes a resolution but signs it with a mechanism that isn’t accredited FEA, the result isn’t “almost valid”: it’s a defective act, challengeable on form. And after 2027, keeping a procedure on paper to dodge the problem isn’t an option either — that’s also defective.

The detail of how FirmaGob is integrated (SOAP/WSDL, institutional certificates, the cascade effect with DocDigital and ClaveUnica) we cover in the guide to the legal framework of Digital Government and, in more depth, in the technical guide to FirmaGob.

Where the mistake slips into a real system

The FEA/FES confusion is rarely a conscious decision. It slips in through three paths, and all three show up in production:

• “Digital signature” that is actually FES. Many platforms are sold as signatures with full legal validity and, in the fine print, generate a simple signature. Before integrating any provider, verify it’s in the official registry of accredited providers. If it isn’t there, it isn’t FEA, no matter what the button is called.
• The flow that mixes the two levels. A system can require FEA for the final act but leave intermediate steps with FES that end up forming part of the record. When that record is audited, the chain breaks at the weak link.
• The integration that “works in the demo.” FirmaGob runs fine on test day and fails in production over certificate handling, token refresh or retries that duplicate signatures. That doesn’t show up in a PDF report; it shows up under real traffic.

It’s right at that border — between what the law requires and what the system actually does — that we work. Connecting systems with Chile’s public infrastructure (FirmaGob, DocDigital, ClaveUnica) and leaving the correct signature at every step is part of what we do at Thinkbox; the same legal-technical judgment with which we built CódigoLegal over 124,000 documents.

The flip side: FEA is an advantage, not a hurdle

It’s easy to read all this as a list of obligations and fines. But it’s worth turning it around, because an advanced signature isn’t bureaucracy: it’s what makes a digital procedure as solid as one before a notary, and sometimes more.

• Legal certainty. A document with FEA reaches court with the presumption in its favor. You don’t have to reconstruct who signed or prove that no one touched it: the law assumes it.
• Non-repudiation. Whoever signed can’t later say “that wasn’t me.” For contracts, administrative acts and powers of attorney, that eliminates an entire category of disputes.
• Verifiable integrity. Any later alteration breaks the signature and becomes visible. The document is auditable by design.
• Real speed. Implemented well, FEA replaces the trip to the notary, the stamped paper and the physical dispatch. What took days is signed and dispatched in minutes, with full traceability.

Doing this well today also leaves the foundation ready for what’s coming: the security and traceability that FEA demands overlap with much of the Law 21,663 on cybersecurity and the Law 21,719 on personal data. It’s not wasted spending; it’s infrastructure that serves three regulations at once.

Checklist: 5 questions to know which signature your procedure requires

Before signing — or before choosing a platform — ask yourself this:

• Does the act produce the effects of a public instrument, or does a specific law require it? If so, it’s FEA, no debate.
• Is it a State administrative act with formal effects? FEA, channeled through FirmaGob if you’re a public organ.
• Who might want to deny this signature tomorrow, and what would I have to prove? If the answer makes you uneasy, move up to FEA.
• Is the “digital signature” provider in the Accreditation Entity’s registry? If it doesn’t show up, it isn’t FEA.
• In my system, do all the steps that form the final record use the correct signature level? The chain is worth only as much as its weakest link.

If you hesitate on two or more, you’re not facing a software problem: you’re facing a validity problem, and it’s better to solve it before a judge or the Comptroller does.

Why this matters to us

Most electronic-signature problems aren’t born of bad faith or ignorance of the law. They’re born in the space between whoever understands the rule and whoever writes the code — two people who often don’t talk to each other. The lawyer assumes the system “already signs correctly”; the developer assumes “any signature will do.” And the mistake stays buried until someone digs it up at the worst possible moment.

Thinkbox largely exists to close that gap: a single team that reads Law 19,799 and 21,180 and then writes the FirmaGob integration that complies with them. We don’t sell a signing certificate; we help your acts, contracts and procedures carry the signature the law requires, actually working in production.

If you’re digitizing procedures with the State or you need your system to sign with legal validity — and to sleep soundly knowing the signature holds up to a challenge — that’s exactly what we do in our Digital Government service.