Electronic signatures are legally valid at every level under eIDAS, but only a Qualified Electronic Signature (QES) is automatically treated as equivalent to a handwritten signature. Simple and advanced signatures are valid too, just easier to dispute.
Under eIDAS Article 25(1), an electronic signature cannot be denied legal effect solely because it’s electronic. That applies at every level. But “can’t be denied legal effect” is different from “automatically treated as equivalent to a handwritten signature.” That stronger guarantee applies to exactly one level.
A typed name, a scanned signature image, an email confirming agreement, a click-to-sign checkbox: all can count as a simple electronic signature. It’s legally valid and usable as evidence, but if a counterparty disputes that it was really them, or that they intended to sign, the burden is on whoever relies on the signature to prove it. There’s no accredited third party standing behind the signing process.
An AdES has to meet four conditions: uniquely linked to the signatory, capable of identifying them, created using signing data the signatory controls, and linked to the document so any later change is detectable. This is stronger evidence than SES, typically backed by an identity check (BankID, for example) and a tamper-evident cryptographic signature. It’s still not automatically equivalent to a handwritten signature, but it’s materially harder to dispute than SES.
A QES adds two requirements on top of AdES: a Qualified Signature Creation Device, and a qualified certificate issued by a Qualified Trust Service Provider listed on the EU trust lists. In exchange, Article 25(2) gives it automatic legal equivalence to a handwritten signature across every EU member state, and the burden of proof shifts: the signature is presumed valid unless the party disputing it can show otherwise. See what a qualified electronic signature is for the full breakdown.
The signing platform used doesn’t automatically tell you the level. Many mainstream e-signature tools default to SES or AdES unless a qualified provider is explicitly used for that specific signature. The only reliable way to know is to check the signature itself, which certificate it was built on, and whether that certificate traces back to a QTSP on the trust lists, rather than trusting the platform’s own summary of what happened.