Biometric contract signing: what it is and how to roll it out in your SME

Printing a contract, scanning it, emailing it, receiving it signed, scanning it again, filing it away in a folder… That is still what most Spanish SMEs do in 2026. Biometric signing does away with that entire process: the employee signs on their phone in 10 seconds and the contract becomes legally binding. In this article we explain exactly what it is, what legal validity it carries and how to roll it out in 48 hours without touching your ERP.

What biometric signing is

A biometric signature is a type of advanced electronic signature that captures the unique data of your stroke as you sign on a touchscreen (phone, tablet):

Pressure applied at each point of the stroke.
Speed and acceleration of the movement.
Cadence (signing rhythm).
Angles and inclinations of the gesture.

All of that data is combined with a cryptographic hash of the document to generate a unique piece of evidence, irreversibly linked to the person signing and to the document they sign.

Legal basis: why it carries the same weight as a handwritten signature

The validity of biometric signing in Spain rests on two regulatory pillars:

Reglamento eIDAS 910/2014 (UE) (EU eIDAS Regulation)

It establishes three levels of electronic signature:

Simple electronic signature: any digital method that identifies the signatory. Limited legal validity (an email saying “agreed” technically counts).
Advanced electronic signature: uniquely identifies the signatory, is indissolubly linked to the document and makes it possible to detect subsequent modifications. Biometric signing falls into this category.
Qualified electronic signature: advanced + qualified certificate + secure device (e.g. signing with the DNIe, the Spanish electronic ID card). The highest legal level.

Being advanced, biometric signing is equivalent to a handwritten signature for the vast majority of documents (art. 25 eIDAS).

Código Civil español (Spanish Civil Code)

Art. 3.10 of the Código Civil declares valid the forms of expressing intent, including digital ones, provided there is reliable evidence (constancia fehaciente). Biometric signing provides it.

Recent case law

Spanish courts have been admitting biometric signatures since 2016. Relevant cases:

TS 2021 (Tribunal Supremo): biometric signature in banking deemed equivalent to a handwritten signature.
TSJ Madrid 2023: employment contract signed biometrically admitted as full evidence.
TSJ Cataluña 2024: a substantial modification of working conditions accepted by biometric signature deemed valid.

What it can be used for in an SME

Practically any HR document:

Employment contracts (permanent, temporary, work-experience, training).
Contract addenda (modifications, changes to working hours).
Remote-working agreements (mandatory under Ley 10/2021).
Dismissal or termination communications.
Confidentiality clauses and non-compete agreements.
Authorisations (image use, data transfer, subsidised training).
Payslips (employee’s acknowledgement of receipt).
Handover of equipment and PPE.
Acceptance of the collective bargaining agreement (convenio colectivo).
Acceptance of the IT tools usage policy.

What you should not sign with biometric signing alone:

Public deeds before a notary (these require a handwritten signature in person).
Documents that must be entered in public registries with a certified signature.
Contracts with foreign companies where the counterparty demands a qualified signature.

For those cases you use a qualified electronic signature with a digital certificate.

How it works technically

The process has 4 phases:

Phase 1 — Document generation

The HR administrator selects a template (e.g. a permanent contract). LapsoWork automatically fills in the employee’s variables (name, DNI, category, salary) and generates the PDF.

Phase 2 — Sending it to the employee

The employee receives a push notification in the app with the document. They can read it in full, download it and add annotations if needed.

Phase 3 — Signing

The employee signs with their finger or a stylus directly on the phone screen. The system captures:

The visual stroke of the signature.
The biometric data of the gesture (pressure, speed, cadence).
The timestamp of the moment of signing.
The device metadata (without intruding on privacy: device model, OS version).
A cryptographic hash of the signed document.

Phase 4 — Sealing and archiving

The system combines the document + signature + biometrics + timestamp into a PDF/A-3 container (a long-term archival format). This container is sealed with a qualified timestamp (TSA) and archived in the document manager with full traceability.

If, years later, someone questions the signature, it can be verified that:

The document has not been modified.
The signature belongs to the person (through expert analysis of the biometrics).
The timestamp is authentic.

Comparison with other methods

Method	Legal validity	Time per signature	Cost	Traceability
Paper + handwritten	Full	5-15 min (print, sign, scan)	Paper + toner + filing	Manual
Editable PDF with a scanned signature	Debatable	5-10 min	Free	Very low
Simple signature (e.g. an “I accept” tick)	Limited	10 sec	Free	Low
Biometric signature	Advanced	10-20 sec	Included in the SaaS	High
Qualified signature (DNIe)	Maximum	2-5 min	Free (requires a certificate)	High

Biometric signing is the sweet spot for everyday employment documents: validity equivalent to a handwritten signature, the speed of a qualified signature, cost included in a SaaS.

How to roll it out in your SME

Day 1 — Set-up (3-4 hours of HR work)

Activate the document manager module with biometric signing (included in LapsoWork’s Basic plan).
Upload the templates for your most common contracts and agreements (permanent, temporary, remote working). LapsoWork detects the variables automatically (name, DNI, etc.).
Tell your employees that new contracts and addenda will be signed via the app. An email template is available.

Day 2 — First pilot contract

Choose a real case (a new contract, an addendum, a change of working hours) and use it as a pilot.
Send it via the app to the employee concerned.
The employee signs from their phone.
Check in the document manager that the document was archived correctly with all its metadata.

The following week — Full rollout

Apply biometric signing to all new documents from that point on.
For the back catalogue already signed on paper, there is no need to migrate it: you keep the physical archive as your requirements dictate.

Typical use cases in the Spanish SME

Fast hiring

A hospitality SME hires a waiter for the weekend. Before: print the contract, wait for the employee, sign, scan, file (30-45 min). Now: generate it in LapsoWork, send it to the employee’s phone, sign (3 min in total).

Mass changes to working hours

A services company moves to a 37.5-hour week under the collective agreement. Before: 80 addenda printed, signed and filed (2-3 days of work). Now: 80 addenda sent as a batch with one click, signed by employees within 24-48h (4h of actual work).

Acceptance of the whistleblowing channel

The entire workforce must receive and accept the internal channel policy. Before: an in-person meeting or an email with a dubious read receipt. Now: a mass send with biometric signing and full traceability.

Frequently asked questions

What if the employee does not have their own smartphone? The company must provide an alternative: a tablet in the office, a computer at reception or a corporate smartphone. If the employee can sign on paper because they refuse to use a device, the law allows it.

Can an employee refuse to sign biometrically? In principle, yes. But if the collective agreement or the contract stipulates it, or if the company justifies it on the grounds of internal protocol, it is normally accepted. In practice, no employee refuses once they see how fast it is.

What validity does it carry abroad? Within the EU, the Reglamento eIDAS guarantees mutual recognition. In non-EU countries it depends on local law: in the UK, Switzerland and the US it is usually accepted; in some Latin American countries a handwritten signature is still required.

And what if someone denies having signed? In the event of a challenge, an expert analysis of the captured biometric data is carried out. A certified forensic graphologist compares the stroke and the patterns with known samples of the signatory. 99% of challenges end up confirming the signature.

Do biometric data count as “sensitive data” under RGPD? Yes, biometric data belong to a special category (art. 9 RGPD, the Spanish/EU data protection regulation). They must be processed on an appropriate legal basis: in the employment context, this is the explicit consent given at the moment of signing + the company’s legitimate interest in document management. LapsoWork handles this compliantly.

Conclusion

Biometric signing is the most efficient and legally valid way to manage an SME’s employment documents in 2026. It saves you hours every week in paperwork, reduces errors and leaves solid cryptographic evidence in the event of any future dispute. With LapsoWork you get it included from the Basic plan (€2/employee/month), at no extra cost.

If you want to roll it out in your SME, you can try LapsoWork free for 30 days to evaluate it with no commitment, or take a look at the document manager module page for all the technical details. And if you have not yet moved from paper to digital, we have a dedicated guide on how to do it in 72 hours.