# The 3 types of electronic signatures

Source: https://contracko.com/blog/types-of-electronic-signatures

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[The 3 types of electronic signatures](https://contracko.com/blog/types-of-electronic-signatures)

# The 3 types of electronic signatures

Lou Van Reemst Jun 17, 2026

Copy for LLM

Not all electronic signatures are created equal. Under EU Regulation 910/2014, better known as eIDAS, there are three distinct tiers of electronic signature: simple (SES), advanced (AdES), and qualified (QES). Each tier corresponds to a different level of security, identity verification, and legal presumption.

Unlike the US ESIGN Act, which treats all valid electronic signatures equally, eIDAS recognizes that different contract situations carry different risk levels. The good news is that most standard business contracts don't need the highest (and most expensive) tier. Here is how to figure out which one fits.

## How we evaluate electronic signature types

To keep this comparison practical rather than theoretical, here are the dimensions that matter when choosing between the three eIDAS signature types:

- Security level, meaning how robust the identity verification is and how well the signing process is protected.
- Legal standing, meaning what evidentiary weight the signature carries in legal proceedings.
- Technical complexity, meaning what implementation requires from your team and your tools.
- Cost and accessibility, meaning the price per signature and how easy it is for signers.
- Appropriate use cases, meaning which contract types and risk levels each tier actually serves.

With those criteria in mind, here is how the three types compare.

## 1. Simple electronic signature (SES)

A simple electronic signature is the most basic form of e-signature under [eIDAS](https://contracko.com/blog/what-is-eidas). The legal definition is broad: any data in electronic form that is attached to or logically associated with other data and used by the signatory to sign. That is it. No specific technical requirements, no mandated identity verification, no cryptographic sealing.

### Why it stands out

SES is the easiest signature type to implement because it covers almost anything electronic that indicates intent to sign. A typed name at the bottom of an email, a checkbox on a web form, a click-to-sign button, or a scanned signature pasted into a document all qualify. If it is in electronic form and signals intent, it counts. There is no requirement for enhanced security or tamper detection at this level.

### Best for

- Internal approvals and routine acknowledgements
- Low-risk situations where the parties already know each other
- Informal agreements, online agreements, or purchase orders with minimal fraud risk
- HR documents like policy acknowledgements

### Key strengths

- Minimal friction in the signing process
- Cost-effective for high-volume, low-risk documents
- Works on any device with no special software or hardware

### Possible limitations

SES carries the lowest evidentiary weight. If a dispute arises, the party relying on the signature has to prove the signer's identity and intent through other means. There is no built-in mechanism to verify who signed or whether the document was altered after signing. For anything beyond routine, low-stakes signing, that gap matters.

## 2. Advanced electronic signature (AdES)

An advanced electronic signature is the practical standard for most business contracts. It is defined in Article 26 of eIDAS and must meet four specific requirements that set it apart from a basic electronic signature.

### Why it stands out

To qualify as an AdES, the signature must be:

1. Uniquely linked to the signer
2. Capable of identifying the signer
3. Created using signature creation data under the signer's sole control
4. Linked to the signed data so that any subsequent change is detectable

In practice, this means strong identity verification at the point of signing, a tamper-evident seal on the signed document, and a comprehensive audit trail. This is what most reputable [electronic signature solutions](https://contracko.com/features/contract-tracking) actually deliver, even when they don't use the term "AdES" in their marketing.

### Best for

- Vendor agreements and service contracts
- Non-disclosure and confidentiality agreements
- SaaS subscriptions and sales contracts
- Employment contracts and legal agreements
- The vast majority of B2B commercial transactions

Roughly 90% of business signing needs are satisfied without ever reaching for QES. Advanced signatures cover that ground.

### Key strengths

- Document integrity is built in, so any change after signing is detectable
- Secure audit trails provide strong evidence in disputes
- Higher security than SES, with identity verification tied to the signer
- Data integrity protections through digital certificates and cryptographic sealing
- Moderate cost, typically between €0.50 and €5 per signature depending on volume

### Possible limitations

AdES requires more technical infrastructure than SES, including certificate management and identity verification workflows. It also costs more per signature than a simple click-to-sign. For standard business and legal contracts, the tradeoff is well worth it. The difference between a signature that ensures document integrity and one that does not can be significant when disputes arise.

## 3. Qualified electronic signature (QES)

A qualified electronic signature sits at the top of the eIDAS hierarchy. It is an advanced electronic signature that adds two critical requirements: it must be created using a qualified signature creation device (QSCD), and it must be based on a qualified certificate issued by a qualified trust service provider on the EU Trusted List.

### Why it stands out

Under Article 25(2) of eIDAS, a QES has the equivalent legal effect of a handwritten signature in all EU member states. This is the only electronic signature type that carries this automatic legal equivalence, and it is the highest legal backing any electronic signature can achieve under EU law.

A qualified certificate issued by a qualified trust service provider enforces strict identity verification standards, and the QSCD protects the signing key from tampering or unauthorized access.

### Best for

- Property transactions where national law requires equivalence to a wet signature
- Notarised documents and government documents
- Court filings and powers of attorney
- High-value transactions where regulatory requirements demand the strongest legal force
- Specific documents where law explicitly mandates QES

### Key strengths

- Highest legal presumption of validity, with recognition across all EU member states
- Strongest legal enforceability of any e-signature tier
- Cannot be denied admissibility in legal proceedings simply because it is electronic
- Ensures both signer identity and document integrity at the highest standard
- Under eIDAS 2.0, EUDI Wallets will enable smartphone-based QES by the end of 2026, reducing the current hardware dependency

### Possible limitations

QES requires a qualified certificate from an EU Trust List provider and a certified signature creation device. That is a technical requirement beyond what standard e-signature platforms provide. Costs typically run between €5 and €25 per signature, making it significantly more expensive than AdES for routine use. Most B2B contracts do not require this level. If national law does not explicitly mandate QES for your document type, you are likely paying for legal compliance you do not need.

## Quick comparison: which signature type for which contract

The table below maps common contract types to the signature tier that actually fits.

| Contract type | Recommended tier | Why |
| --- | --- | --- |
| Vendor agreements, service contracts | AdES | Identity verification plus tamper detection covers the risk |
| Non-disclosure agreements | AdES (SES for lower-risk cases) | Depends on value and sensitivity |
| SaaS subscriptions | AdES or SES | AdES for significant commitments, SES for routine sign-ups |
| Employment contracts | AdES | Regulatory and evidential weight matters |
| Property transactions (EU) | QES (check local law) | Often legally required to equal a handwritten signature |
| Notarised or certified documents | QES | Law typically mandates the highest tier |
| Internal approvals, routine acknowledgements | SES | Low risk, known parties, minimal stakes |
| Purchase orders | SES or AdES | Depends on value and counterparty relationship |

The pattern is clear. AdES is the sweet spot for standard business processes and legal agreements, SES works for low-stakes situations, and qualified signatures are reserved for cases where the law specifically demands them.

## How to choose the right electronic signature type

### Choose based on contract risk level

Match the signature type to the actual risk, not to theoretical worst cases:

- Low risk, known parties: SES is sufficient. Internal record keeping, routine acknowledgements, and basic form approvals are often handled in a [lightweight contract repository](https://contracko.com/features/contract-repository).
- Standard business contracts: AdES is appropriate. This covers the vast majority of scenarios where you sign documents electronically with external parties.
- High-stakes legal requirements: QES is necessary only when national law explicitly requires the legal validity of a handwritten-signature equivalent.

### Choose based on legal requirements

Before defaulting to the highest tier, check whether your specific document type actually requires it. Most commercial agreements, including sales contracts, vendor agreements, and confidentiality agreements, have no QES requirement under EU law. An [electronic signature is legally binding](https://contracko.com/blog/is-an-electronic-signature-legally-binding) at all three levels, and your choice of [pricing plan](https://contracko.com/pricing) should reflect how often you use each tier. The difference is in the burden of proof if things go to court.

### Choose based on technical capabilities

SES and AdES are available through standard e-signature platforms and [contract management systems](https://contracko.com/blog/contract-management-system). QES requires specialized providers with qualified certificates and, in many cases, dedicated hardware or certified software. Weigh implementation complexity against your actual legal need before investing in QES infrastructure.

## Which electronic signature type is best for you?

Here is the direct answer, because this should not end with "it depends":

- Choose SES for simple, low-risk internal signing where parties are known and stakes are low.
- Choose AdES for standard business contracts. This is the right choice for roughly 80 to 90% of signed business agreements, including those managed by [purchasing and procurement teams](https://contracko.com/usecases/purchasing). It delivers strong identity verification, tamper-evident sealing, solid audit trails, and legal standing that holds up in disputes.
- Choose QES only when national law specifically requires it for your document type, or when you are handling high-value transactions like property transfers or notarial acts where full legal force is a regulatory requirement.

If you are unsure, AdES is almost certainly the right starting point.

## A note on the US framework

For a business operating exclusively in the United States, the tier question does not apply in the same way. Under the ESIGN Act and the Uniform Electronic Transactions Act (UETA), an electronic signature is broadly defined as any electronic sound, symbol, or process attached to a record with intent to sign.

The US framework does not classify signatures into tiers. Any valid electronic signature meeting consent, intent, and record-retention requirements has legal validity. There is no separate category for advanced or qualified signatures. For companies with EU operations or EU counterparties, aligning with eIDAS tiers still provides meaningful legal certainty. Reliable [contract tracking across jurisdictions](https://contracko.com/features/contract-tracking) also helps ensure renewals, expirations, and obligations are handled correctly when contracts cross into EU jurisdiction.

## Final thoughts

The three types of electronic signatures under eIDAS exist for a reason: different contracts carry different risks, and the signing process should match. Understanding the difference between SES, AdES, and QES means you can make an informed choice rather than defaulting to either the cheapest or the most expensive option.

For most business contracts, AdES is the answer. It provides the identity verification, document integrity, and legal standing that a commercial [contract repository](https://contracko.com/features/contract-repository) demands, without the cost and complexity of QES.

Contracko's built-in e-signature feature delivers AdES-level signatures with strong identity verification, tamper-evident sealing, and a full audit trail. Once signed, your contracts flow directly into [AI-powered contract analysis](https://contracko.com/features/ai-contract-analysis) with automatic extraction, smart reminders, and obligation tracking.

You can try it with a [7-day free trial](https://contracko.com), no credit card required. Plans start from $75/month.

## Sources

[1] SignQuick, signquick.app [2] Wikipedia, wikipedia.org [3] Deloitte, deloitte.com

Images in this article were generated with the assistance of AI.

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