Both laws say the same thing. Then they diverge
Start with what they agree on, because it is more than most people expect.
The ESIGN Act (US, federal) and eIDAS (EU, Regulation 910/2014) share a founding principle: an electronic signature cannot be denied legal effect solely because it is electronic. Add UETA, adopted by 49 US states for intrastate transactions, and the picture is consistent across both jurisdictions.
If that were the whole story, this article would end here. It is not.
The structural difference
The US model is single-tier and technology-neutral. ESIGN and UETA define one category of electronic signature. Any method that shows intent to sign and is attributable to the signer qualifies. A typed name, a drawn mark, a click, all valid, with evidentiary weight decided case by case.
The EU model is tiered. eIDAS defines three levels, and the difference between them is not marketing:
| Level | What it requires | Legal weight |
|---|---|---|
| Simple (SES) | Any electronic data used to sign | Cannot be denied validity for being electronic. Burden of proof is yours |
| Advanced (AdES) | Uniquely linked to signatory, under their control, detects tampering | Stronger evidence, still not equal to handwriting |
| Qualified (QES) | AdES + qualified certificate from a QTSP + qualified signature device | Legally equivalent to a handwritten signature, automatically, in every Member State |
That last row is Article 25 of eIDAS, and it is the only place in either legal system where a law hands you equivalence rather than asking a court to weigh evidence.
Where the difference bites
For most contracts, it does not. A commercial services agreement, an NDA, a purchase order, no form requirement, any tier works, and the practical choice is about friction, not law.
The difference bites in two situations.
When national law prescribes written form. Several Member States require Schriftform or its equivalent for specific contracts, and permit electronic execution only via QES. Germany's §126a BGB is the clearest example, but similar constraints exist elsewhere. A US-tier signature does not satisfy these, no matter how complete the audit trail.
When you need certainty rather than argument. With SES or AdES, if the other side disputes the signature, you prove it, with logs, IP addresses, timestamps. With QES, the burden shifts. The signature is presumed equivalent to a handwritten one, and the person disputing it carries the weight.
For a low-value recurring contract, that distinction is academic. For an eight-figure agreement, or an employment relationship you may one day have to defend, it is the whole point.
The practical rule
If you operate across both jurisdictions, the useful heuristic is this:
Build for AdES as your default. It satisfies US law comfortably, the US has no tiers to fall short of, and gives EU counterparties meaningfully stronger assurance than a bare simple signature.
Escalate to QES where it is mandated or where the stakes justify it. Statutory written form requirements. High-value agreements. Anything where a dispute is foreseeable.
Do not use QES everywhere. It requires identity verification for each signatory. That is friction, and friction costs deals. Applying it to routine documents slows your business to protect against a risk that is not there.
Which tier a given contract actually needs depends on the governing law and on what is at stake, and getting it wrong costs either a deal or unnecessary friction.
What QES requires that AdES does not
Two things, and both are supervised rather than self-declared:
A qualified certificate from a Qualified Trust Service Provider, a provider audited and granted qualified status by an EU Member State supervisory authority, and published on that state's official Trusted List. Anyone can call themselves secure. Only audited providers appear on a Trusted List.
A qualified signature creation device, so the signing keys remain under the signatory's sole control.
This is why QES carries the legal weight it does: the identity behind the signature was verified to a standard a regulator supervises, not to a standard a vendor chose.
The misconception that blocks deals
"QES is only for Europeans."
It is not. Nationality and residency do not determine eligibility. What matters is that a qualified certificate is issued by an EU-qualified provider, following identity verification that meets qualified standards.
A US, UK or Australian signatory can hold a qualified certificate. The historical obstacle was the identity check, traditionally in person, which international deals cannot accommodate.
Remote identity verification removed that obstacle. The signatory verifies identity remotely through a supervised process, a qualified certificate is issued in their name, and the signature they produce carries full eIDAS weight.
At WallID Smart Sign, qualified certificates are issued through a European Qualified Trust Service Provider operating under the strictest supervisory requirements, with legal validity across the EU. The signatory needs no EU residency, no national eID and no travel, only a valid identity document.
A short decision guide
| Your situation | What you need |
|---|---|
| US-only contract, no EU exposure | Any ESIGN/UETA-compliant signature |
| EU commercial contract, no form requirement | SES or AdES is sufficient and faster |
| German employment contract, fixed term | QES, §126a BGB |
| Any contract where national law requires written form | QES |
| High-value agreement, dispute foreseeable | QES, for the reversed burden of proof |
| Signatories in multiple countries | QES, one standard recognised in all Member States |
Frequently asked questions
What is the main difference between eIDAS and the ESIGN Act? Structure. The ESIGN Act uses one technology-neutral category of electronic signature. eIDAS defines three tiers, simple, advanced and qualified, where only the qualified tier is legally equivalent to a handwritten signature across all EU Member States.
Is an ESIGN-compliant signature valid in the EU? Generally yes. eIDAS prohibits denying an electronic signature legal effect solely because it is electronic. But it will not satisfy a national law that specifically requires written form, where only a qualified electronic signature is accepted.
Is a qualified electronic signature valid in the United States? Yes. Under ESIGN and UETA any electronic signature showing intent and attributable to the signer is valid, and a QES exceeds those requirements comfortably. The tiering only matters in the EU direction.
Do I always need a qualified electronic signature for EU contracts? No, and using it everywhere adds unnecessary friction. Most commercial contracts have no form requirement. QES is needed where national law mandates written form, or where the value of the agreement justifies the stronger evidentiary position.
What does "qualified" actually mean? That the certificate comes from a Qualified Trust Service Provider, audited and supervised by an EU Member State authority and listed on its official Trusted List, and that the signature is created on a qualified device under the signatory's sole control. It is a supervised status, not a self-declared one.
Can a company outside the EU issue qualified signatures to its staff? The certificates are issued to individuals, not companies, by an EU-qualified provider. There is no requirement that the individual or their employer be based in the EU. Identity verification can be completed remotely.
Working out which signature level your contracts require? Talk to us.