A client asks you to sign a contract using an Advanced Electronic Signature (AES). You already use electronic signatures for everyday agreements, so what's different about this one?
An Advanced Electronic Signature (AES) is a specific category of electronic signature defined under the European Union's eIDAS Regulation. It must be linked to the signer, capable of identifying them, created using signature data under their control, and connected to the signed document so subsequent changes can be detected.
That sounds technical, but the practical question is simple: what level of signing assurance does your document actually require?
Not every contract needs an AES, and not every electronic signature platform automatically provides one. This guide explains the requirements, compares AES with other signature types, and walks through choosing and using an appropriate signing method.
At a Glance: Advanced Electronic Signature
| Feature | Details |
|---|---|
| Full form | Advanced Electronic Signature |
| Legal framework | EU eIDAS Regulation, Article 26 |
| Main purpose | Establish a stronger connection between the signer, signature, and signed data |
| Core requirements | Unique linkage, signer identification, signer control, and change detection |
| Common applications | Business agreements and transactions requiring stronger signing assurance |
| Qualified certificate required? | Not necessarily for AES |
| Same as QES? | No. Qualified Electronic Signatures have additional requirements |
| Legally recognized? | Yes, with legal effect depending on the transaction and applicable requirements |
What Is an Advanced Electronic Signature (AES)?
An Advanced Electronic Signature is an electronic signature that satisfies four specific requirements established by the EU's eIDAS Regulation.
Unlike a basic signature created by typing your name into a document, an AES must meet technical and procedural conditions intended to create a stronger connection between the signer and the signed information.
An AES is not defined by how the signature looks.
A signature might appear as a typed name, handwritten mark, or other visual representation. What determines whether it qualifies as advanced is the underlying signing process and whether that process satisfies the applicable requirements.
The Four Requirements of an AES
Under Article 26 of the eIDAS Regulation, an Advanced Electronic Signature must meet all four conditions.
1. Uniquely linked to the signer
The signature must have a unique connection to the individual signing the document.
This helps distinguish the signer's signature from those created by other people.
2. Capable of identifying the signer
The signing method must support identification of the person associated with the signature.
Simply displaying someone's name does not automatically satisfy this requirement.
3. Created using signature data under the signer's control
The signature must be created using electronic signature creation data that the signer can, with a high level of confidence, use under their sole control.
This may involve appropriate cryptographic credentials and technical safeguards.
4. Linked to the signed data so changes are detectable
The signature must be associated with the signed information in a way that makes subsequent changes detectable.
This helps recipients investigate whether the signed content has been altered.
All four requirements must be satisfied for the signature to qualify as AES.
An audit trail, email confirmation, or document hash may support a signing process, but no single feature automatically establishes compliance with every requirement.
SES vs. AES vs. QES: What's the Difference?
Electronic signatures are commonly grouped into three levels under the EU's eIDAS framework: Simple Electronic Signature (SES), Advanced Electronic Signature (AES), and Qualified Electronic Signature (QES).
These categories have different requirements.
| Feature | SES | AES | QES |
|---|---|---|---|
| Basic electronic signing | Yes | Yes | Yes |
| Unique linkage to signer required | No specific AES requirement | Yes | Yes |
| Signer control requirement | No specific AES requirement | Yes | Yes |
| Detection of later changes required | Not inherently | Yes | Yes |
| Qualified certificate required | No | No | Yes |
| Qualified signature creation device required | No | No | Yes |
| Automatic handwritten-signature equivalence under eIDAS | No | No | Yes |
Simple Electronic Signature (SES)
A simple electronic signature is the broadest category.
Depending on the circumstances, it can include:
- Typing a name into a document.
- Drawing a signature with a mouse or finger.
- Inserting a scanned signature.
- Completing an electronic agreement using an appropriate signing action.
An SES does not automatically provide the technical assurances required for an AES.
However, that does not make simple electronic signatures legally worthless.
Under eIDAS Article 25, an electronic signature cannot be denied legal effect or admissibility as evidence solely because it is electronic or because it does not meet the requirements for a qualified electronic signature.
For many everyday agreements, a simple electronic signature may be appropriate.
Advanced Electronic Signature (AES)
An AES must satisfy the four requirements in Article 26.
Its defining characteristics include signer linkage, identification capability, signer control, and detection of subsequent changes.
It may be appropriate when the parties want greater assurance about how a document was signed or when a specific transaction requires an advanced signature.
Qualified Electronic Signature (QES)
A QES is an Advanced Electronic Signature that meets additional conditions.
It must be created using a qualified electronic signature creation device and be based on a qualified certificate for electronic signatures.
Qualified certificates are issued by qualified trust service providers.
Under eIDAS Article 25, a QES has the equivalent legal effect of a handwritten signature.
This does not mean that every business document requires QES.
The appropriate level depends on applicable law, the transaction, and the receiving party's requirements.
How to Obtain and Use an Advanced Electronic Signature
Using an AES requires more than selecting a signature font or inserting an image into a PDF.
The signing solution and its procedures must satisfy the relevant requirements.
Here is a practical process.
Step 1: Confirm Whether Your Document Requires AES
Before choosing software, establish what level of signature you need.
Ask:
- Does the receiving party specifically require AES?
- Is the transaction governed by EU or another applicable electronic signature framework?
- Are there sector-specific requirements?
- Does the document require QES or another formal signing method?
- Would a simpler electronic signature satisfy the transaction's requirements?
For example, a freelance service agreement may not require the same level of assurance as a transaction governed by specific regulatory rules.
Don't assume that a higher signature level is mandatory simply because the agreement involves money.
Step 2: Choose a Signing Solution That Supports AES
Find a provider that explicitly supports Advanced Electronic Signatures under the applicable eIDAS requirements.
Review its documentation rather than relying only on general claims such as "secure electronic signatures" or "legally binding signatures."
Look for information explaining:
- How the signer is identified.
- How the signature is uniquely linked to the signer.
- How signature creation data is protected.
- How signer control is maintained.
- How changes to signed data are detected.
- How completed signatures can be validated.
Ask the provider to identify the relevant AES signing method and any required configuration.
Not every electronic signature service supports AES, and some may offer it only through a specific workflow or integration.
Step 3: Complete the Required Identification Process
Follow the identity verification procedure required by the chosen AES solution.
The precise method depends on the provider and signing process.
Some signing services may use additional identity checks, authentication credentials, or certificate-based mechanisms.
An email link or SMS code can form part of a signing workflow, but these measures do not independently establish AES compliance.
What matters is whether the entire process satisfies the applicable legal and technical requirements.
Step 4: Prepare and Review the Document
Upload the document using the supported file format.
Before signing, check that:
- The correct document version is being used.
- All pages are present.
- Names, dates, and agreement terms are accurate.
- All necessary signature fields are included.
- The intended signers are identified.
If several people need to sign, confirm how the service manages multiple signatures and any required signing order.
Making corrections before signing is generally easier than resolving document-version disputes afterward.
Step 5: Apply the Advanced Electronic Signature
Follow the signing instructions supplied by the provider.
Depending on the solution, this may involve an authentication step, confirmation of signing intent, and use of protected signature creation data.
The interface may still display a familiar signature field.
However, the underlying signing process must meet the four AES criteria.
Do not assume that drawing or typing a name automatically creates an AES.
Step 6: Validate the Completed Signature
After signing, use an appropriate validation method supported by the service or signature format.
Check the available information about:
- Signature validity.
- Signer identification.
- Certificate or credential details, where applicable.
- Integrity of the signed data.
- Relevant validation warnings.
The exact validation process depends on the signature technology used.
If the recipient requires AES, confirm that the completed signature meets their validation requirements.
Step 7: Save the Signed Document and Supporting Records
Keep the completed document and relevant signing evidence together.
Depending on the provider, these records may include:
- A signed PDF.
- Signature validation information.
- Certificate details.
- Signing timestamps.
- Audit or transaction records.
- Confirmation of the signing method.
These records can help explain how the document was signed if questions arise later.
An audit trail is useful supporting evidence, but it does not replace the four requirements of an AES.
When Should You Use an Advanced Electronic Signature?
AES can be useful when a basic electronic signature does not provide the level of assurance required by the parties or transaction.
However, it is not universally necessary for ordinary business documents.
Client Contracts and Service Agreements
Freelancers and agencies regularly exchange service agreements, statements of work, and project contracts.
In many situations, a general electronic signature may be sufficient.
AES may be appropriate when the client explicitly requires it or when stronger evidence of signer linkage and document integrity is important.
Non-Disclosure Agreements
An NDA may involve commercially sensitive information.
The parties may decide that an advanced signature provides appropriate signing assurance.
However, NDAs do not automatically require AES solely because they contain confidential information.
HR and Employee Documents
Businesses may use electronic signatures for offer letters, acknowledgments, and onboarding documents.
The required signature method depends on the jurisdiction, employment rules, and document type.
Some employment transactions may have specific requirements that should be checked separately.
Transactions With Higher Verification Requirements
An AES may be useful where confirming signer involvement and detecting changes are particularly important.
Examples can include certain regulated workflows or transactions subject to specific organizational requirements.
The appropriate signature level should be determined from the applicable rules rather than assumed from the value of the transaction alone.
Is an Advanced Electronic Signature Legally Binding?
An AES is recognized under the EU's eIDAS Regulation, but legal recognition does not mean every agreement signed with AES is automatically enforceable.
Article 25 protects electronic signatures from being denied legal effect solely because they are electronic or do not meet QES requirements.
However, only QES receives automatic handwritten-signature equivalence under eIDAS.
Whether a particular AES is sufficient depends on the document, applicable laws, and the circumstances of signing.
What About the United States?
The United States generally follows a different legal framework.
The federal ESIGN Act and applicable state electronic-transactions laws generally take a technology-neutral approach to electronic signatures.
They do not create a direct nationwide SES, AES, and QES classification equivalent to eIDAS.
For many U.S. business agreements, an electronic signature does not have to qualify as AES under EU rules.
Other requirements may still apply, including consent, attribution, record retention, transaction-specific rules, or exceptions.
What About International Contracts?
Cross-border agreements can involve different electronic signature laws.
Before signing, identify the relevant jurisdictions and the receiving party's requirements.
Do not assume that using AES automatically satisfies every country’s signature, notarization, or regulatory requirements.
When Is AES Not Enough?
An Advanced Electronic Signature does not replace every formal signing process.
Some transactions may require a specific signature level or additional procedures.
When QES Is Specifically Required
If applicable rules require a Qualified Electronic Signature, AES alone does not satisfy that requirement.
Use a signing solution that supports the required qualified certificate and qualified signature creation device.
When Notarization Is Required
Electronic signing and notarization are separate legal questions.
A document that must be notarized may require additional identity checks, witnessing, a notarial act, or use of a legally authorized electronic or remote notarization process.
An AES does not automatically replace those procedures.
When the Receiving Party Has Specific Requirements
A business, regulator, or public authority may require signatures in a particular format or through an approved method.
Confirm those requirements before signing.
Using a technically valid AES may not solve a submission problem if the recipient requires a different signature method.
How to Choose the Right Electronic Signature Type
You don't necessarily need the highest available signature level for every document.
Use this decision process.
- Identify the applicable law. Determine whether the document is governed by EU, U.S., or another jurisdiction's requirements.
- Check the recipient's instructions. Look for any explicit SES, AES, QES, or other signature requirements.
- Assess the signing risk. Consider the importance of identifying the signer, protecting document integrity, and retaining evidence.
- Confirm the provider's capabilities. Verify that the signing solution supports the necessary signature level.
- Review the completed evidence. Preserve the final document and relevant validation or transaction records.
| Situation | Likely approach | What to confirm |
|---|---|---|
| Routine agreement with no prescribed signature level | Appropriate electronic signature | Applicable law and recipient acceptance |
| Recipient explicitly requires AES | Advanced Electronic Signature | Provider meets all four Article 26 criteria |
| Law requires QES | Qualified Electronic Signature | Qualified certificate and creation-device requirements |
| Agreement requires notarization | Legally authorized notarization process | Jurisdiction-specific formalities |
| Cross-border business agreement | Method satisfying applicable rules | Recognition, format, and recipient requirements |
When in doubt, confirm the signature requirements before sending the document rather than choosing a signing method based only on its name.
Common Mistakes When Using an Advanced Electronic Signature
Assuming Every E-Signature Platform Provides AES
An electronic signature service may offer document uploads, signing fields, reminders, and audit trails without necessarily meeting every AES requirement.
Check the provider's technical and compliance documentation.
Believing Email Verification Alone Is Enough
Confirming access to an email account can support a signing workflow.
It does not automatically establish unique signer linkage, identification, sole control of signature creation data, and change detection.
AES requires all four criteria.
Confusing an Audit Trail With AES Compliance
An audit trail may record signing activity, timestamps, and related events.
Those records can support transaction evidence, but they do not independently establish the required technical characteristics of an AES.
Assuming AES and QES Have the Same Legal Effect
Both categories are recognized under eIDAS, but they have different requirements.
QES receives automatic equivalence to handwritten signatures under the regulation.
AES does not receive that same automatic equivalence.
Ignoring the Recipient's Requirements
A signature may satisfy one legal or technical standard but still fail to meet a specific recipient's submission requirements.
Check the required format, validation method, and signature level before signing.
Failing to Preserve Supporting Records
Keep the final signed document and relevant validation information.
This can help establish which document was signed and what evidence is available if the transaction is later questioned.
How LoreSign Fits Into Everyday Electronic Signing
Not every business document requires an Advanced Electronic Signature.
For freelancers, consultants, agencies, and small businesses, many routine signing workflows involve preparing agreements, collecting signatures, and maintaining completion records.
LoreSign helps manage these everyday electronic signing tasks.
Its features include:
- Uploading PDF documents.
- Adding signature, name, date, and initial fields.
- Assigning fields to recipients.
- Managing multiple signers and signing order.
- Sending signing requests and reminders.
- Tracking document status.
- Maintaining audit trails and Certificates of Completion.
- Reusing document templates.
These capabilities can simplify routine agreement workflows.
For example, an agency can prepare a service agreement, assign signing fields to the client, send the request, and track completion without manually exchanging signed document versions.
However, LoreSign's general signing features should not be treated as proof of AES or QES compliance.
If a transaction specifically requires an Advanced Electronic Signature under eIDAS, confirm whether the required signing method is available and whether it satisfies all applicable criteria.
The important distinction is between having a convenient electronic signing workflow and meeting a specific legal signature classification.
The Bottom Line
An Advanced Electronic Signature is more than a signature image or an ordinary document-signing action.
- AES has four legal requirements. It must uniquely link to the signer, support identification, use signature creation data under the signer's control, and make subsequent changes detectable.
- Not every document needs AES. Many everyday agreements can use other electronic signature methods, depending on applicable law and recipient requirements.
- AES and QES are different. QES has additional qualified certificate and signature creation-device requirements.
- Email verification and audit trails are not enough by themselves. The complete signing process must satisfy the AES criteria.
- Verify the provider's capabilities. Choose a solution that explicitly supports the required signature level.
- Keep supporting records. Preserve the signed document and relevant validation information for future reference.
For everyday contracts and business agreements where a specific AES or QES level is not required, LoreSign provides a straightforward way to prepare documents, collect electronic signatures, and track completion.
Frequently Asked Questions
1. What is an Advanced Electronic Signature (AES)?
An Advanced Electronic Signature is an electronic signature that meets the four requirements in Article 26 of the EU's eIDAS Regulation. It must be uniquely linked to the signer, capable of identifying them, created using signature creation data under their control, and connected to the signed information so later changes can be detected.
2. What are the three types of electronic signatures?
The three commonly discussed levels under eIDAS are Simple Electronic Signature (SES), Advanced Electronic Signature (AES), and Qualified Electronic Signature (QES). SES is the broadest category. AES must meet four specific requirements, while QES adds qualified certificate and qualified signature creation-device requirements.
3. Is an Advanced Electronic Signature legally binding?
An AES can have legal effect under eIDAS and cannot be denied legal effect solely because it is electronic or does not qualify as QES. However, whether it is sufficient for a specific agreement depends on applicable law and transaction requirements. Only QES receives automatic handwritten-signature equivalence under eIDAS.
4. How do I create an Advanced Electronic Signature?
First, confirm that your document requires AES. Then choose a signing provider that explicitly supports AES under the applicable rules. Complete its identification and signing procedures, validate the completed signature where appropriate, and retain the signed document and supporting records.
5. Does an email OTP make an electronic signature an AES?
Not automatically. Email or SMS verification may support signer authentication, but an AES must satisfy all four Article 26 requirements. These include unique linkage, identification capability, a high level of confidence in signer control over signature creation data, and detectable changes to the signed content.
6. When do I need a Qualified Electronic Signature instead of AES?
You need QES when applicable law or a relevant transaction requirement specifically calls for it. QES requires a qualified certificate and a qualified signature creation device. Not every notarized document, contract, or business transaction universally requires QES, so check the rules for the specific document and jurisdiction.
About LoreSign
LoreSign is an electronic signature platform that helps freelancers, consultants, agencies, and small businesses prepare documents and collect signatures online.
With document uploads, signature fields, recipient management, reusable templates, reminders, audit trails, and completion tracking, LoreSign helps streamline everyday business signing workflows.
Our guides explain electronic signatures, document preparation, signing requirements, and practical ways to manage agreements with greater clarity.
