Simple vs Advanced vs Qualified E-Signatures — Which Do You Need?

Not All Electronic Signatures Are the Same

When someone says "electronic signature," they could mean anything from clicking an "I Accept" button to applying a cryptographic digital certificate issued by a government-accredited authority. These are vastly different things with different legal implications.

Understanding the distinctions matters — especially if you work with international contracts, regulated industries, or government agencies. This guide breaks down the three recognized levels of electronic signatures and helps you determine which one you actually need.

The Three Levels of Electronic Signatures

The most widely referenced framework for electronic signature levels comes from the eIDAS Regulation (EU 910/2014), which defines three tiers. While eIDAS is a European regulation, its classification system has become the global standard for discussing e-signature types.

Level 1: Simple Electronic Signature (SES)

A simple electronic signature is the broadest category. It includes any data in electronic form that is attached to or logically associated with other electronic data and used by the signatory to sign.

Examples of simple electronic signatures:

Drawing a signature on a touchscreen or with a mouse
Typing your name in a signature field
Clicking an "I Agree" or "I Accept" button
Pasting an image of your signature onto a document
Checking a checkbox on a form
Signing with a finger on a delivery device

Legal status: Simple electronic signatures are valid in most countries for most purposes. Under the ESIGN Act and UETA in the United States, and under eIDAS in the EU, simple electronic signatures cannot be denied legal effect solely because they are in electronic form.

When a simple signature is sufficient:

Employment contracts and offer letters
Freelance agreements and SOWs
Lease agreements (most jurisdictions)
Sales contracts and purchase orders
NDAs and confidentiality agreements
Permission slips and consent forms
Internal company approvals
Most day-to-day business documents

When you sign a PDF using SigPDF, you are creating a simple electronic signature. For the overwhelming majority of personal and business use cases, this is all you need.

Level 2: Advanced Electronic Signature (AES)

An advanced electronic signature meets stricter requirements defined by eIDAS Article 26. An AES must:

Be uniquely linked to the signatory — The signature is connected to a specific individual, not a shared credential
Be capable of identifying the signatory — The signature can be traced back to the person who created it
Be created using electronic signature creation data under the sole control of the signatory — Only the signer has access to the signing key or mechanism
Be linked to the data signed so that any subsequent change is detectable — Tampering with the document after signing is visible

How AES works in practice: Advanced electronic signatures typically use public key infrastructure (PKI). The signer has a private key (stored on their computer, a smart card, or a cloud HSM) and a corresponding public certificate. When they sign a document, the private key creates a cryptographic signature that is embedded in the PDF. Anyone can verify the signature using the public certificate, and any modification to the document after signing will break the signature validation.

Examples of AES:

Signing a PDF with a digital certificate stored in your browser or on a USB token
Using a PKI-based signing platform that verifies your identity
Signing with a certificate issued by a certificate authority (CA)

When an advanced signature is needed:

Financial contracts where tamper detection is important
Documents exchanged between organizations that need cryptographic verification
Some regulated industries that require identity verification
Government tenders and procurement in certain EU member states
When the counterparty specifically requires it

Level 3: Qualified Electronic Signature (QES)

A qualified electronic signature is the highest level under eIDAS. It is an advanced electronic signature that additionally:

Is created by a qualified electronic signature creation device (QSCD) — a hardware device (smart card, USB token, or cloud HSM) that meets specific security certification requirements
Is based on a qualified certificate for electronic signatures — issued by a trust service provider that is listed on an EU member state's trusted list

What makes QES special: Under eIDAS, a qualified electronic signature is the only type that has the automatic legal equivalent of a handwritten signature across all EU member states. While simple and advanced signatures can also be legally valid, their legal effect may vary between jurisdictions. A QES is universally recognized.

Examples of QES:

Signing with an EU national eID card (e.g., Belgian eID, Estonian ID-kaart)
Signing with a qualified certificate from a trust service provider like D-Trust, InfoCert, or Swisscom
Using a qualified remote signing service that stores keys in a certified HSM

When a qualified signature is required:

Real estate transactions in some EU member states (e.g., Austria, Belgium)
Certain government submissions and regulatory filings in the EU
Court documents in some jurisdictions
Public procurement in specific EU countries
Any situation where a law specifically requires a "handwritten equivalent" in the EU

How the Three Levels Compare

| Characteristic | Simple (SES) | Advanced (AES) | Qualified (QES) | |---------------|-------------|-----------------|-----------------| | Identity verification | None required | Must identify signer | Government-level verification | | Tamper detection | No | Yes (cryptographic) | Yes (cryptographic) | | Hardware required | No | Optional | Yes (certified device) | | Certificate required | No | Yes (any CA) | Yes (qualified CA only) | | Cost | Free | Varies ($50-500/year) | $100-300/year + device | | Setup time | Seconds | Hours to days | Days to weeks | | Legal status (EU) | Valid, but may need evidence | Valid, stronger evidence | Equivalent to handwritten | | Legal status (US) | Valid (ESIGN/UETA) | Valid (ESIGN/UETA) | Not separately recognized* |

*The United States does not differentiate between signature levels. Under ESIGN and UETA, all electronic signatures are treated the same — their enforceability depends on the intent and consent of the parties, not the technology used.

Which Level Do You Actually Need?

You need a Simple Electronic Signature (SES) if:

You are signing everyday business documents
You are in the United States, where signature levels are not legally distinguished
The other party accepts simple e-signatures (most do)
You want to sign quickly without setup or certificates
The document is a standard contract, agreement, or form

This covers roughly 95% of all signing scenarios. SigPDF creates simple electronic signatures — you draw your signature, place it on the document, and download. No certificates, no hardware, no setup.

You need an Advanced Electronic Signature (AES) if:

You need cryptographic proof that the document was not altered after signing
You are in a regulated industry that specifies AES
The counterparty or a legal requirement demands identity-linked signatures
You are working on high-value contracts where non-repudiation matters

You need a Qualified Electronic Signature (QES) if:

A specific EU regulation or member state law requires it
You are involved in real estate transactions in certain EU countries
You are submitting documents to EU government entities that mandate QES
You need the legal equivalent of a handwritten signature across all 27 EU member states

Digital Certificates: The Technology Behind AES and QES

Both advanced and qualified signatures rely on digital certificates. Here is a brief overview of how they work:

A certificate authority (CA) verifies your identity and issues a digital certificate containing your public key
You store the private key on your computer, a smart card, a USB token, or in a cloud HSM
When you sign a document, your PDF software uses the private key to create a cryptographic hash of the document
The hash is embedded in the PDF along with your certificate
Anyone verifying the signature can use your public certificate to confirm that the document has not been altered and that the signature came from your private key

For qualified signatures, both the certificate and the key storage device must meet additional certification requirements set by EU standards.

Getting a Digital Certificate

If you determine that you need an AES or QES, here is how to obtain a digital certificate:

For Advanced Signatures

Purchase a document signing certificate from a certificate authority like DigiCert, GlobalSign, or Sectigo
Prices range from $50 to $500 per year depending on the CA and validation level
Installation varies by operating system and PDF software

For Qualified Signatures

Apply through a qualified trust service provider listed on an EU trusted list
Requires in-person or video identity verification
You will receive a qualified certificate and a QSCD (smart card, USB token, or cloud HSM access)
The process typically takes several days to a few weeks

The Practical Takeaway

Most people overthink electronic signature levels. Unless you are operating in a regulated EU context that explicitly requires advanced or qualified signatures, a simple electronic signature is legally valid and practically sufficient.

The next time you need to sign a PDF, you probably do not need a digital certificate, a smart card, or a trust service provider. You need SigPDF. Open it, sign your document, and move on.

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