Timestamping is the technique that proves a digital document existed at a specific moment and has not been modified since.
In legal terms, this certainty is what separates solid evidence from a document a judge can question.
Here we explain how it works, what eIDAS and Law 6/2020 say, when it is required and how Legalpin’s certified communications incorporate qualified time stamps that reinforce the probative value of every message sent.
What timestamping is and how it works
A time stamp cryptographically binds a digital document or piece of data to a precise date and time, issued by a Time Stamping Authority (TSA).
The technical process, defined in RFC 3161, is straightforward to understand in three steps.
First, a hash (digital fingerprint) of the document is calculated. Second, that hash is sent to the TSA. Third, the TSA returns a signed response containing the hash and the time mark, guaranteeing that the content has not changed by a single bit since that moment.
Difference between a simple timestamp and a qualified seal
A simple time stamp can be generated by any system or server: it records the date, but it does not offer solid legal guarantees because it does not come from a recognised trust authority.
A qualified time stamp is issued by a Qualified Trust Service Provider (QTSP) listed on the European trust list (ETSI EN 319 421).
The difference is legal: the qualified stamp carries a presumption of accuracy of the date and integrity of the data before the courts of the European Union.
| Feature | Simple stamp | Qualified stamp |
|---|---|---|
| Issuer | Any system | QTSP on EU trust list |
| Legal framework | No specific regulation | eIDAS Art. 41-42, ETSI EN 319 421 |
| Legal presumption | None automatic | Yes, before European courts |
| Recommended use | Internal audit | Litigation evidence, compliance |
| Cross-border validity | Limited | Recognised across the EU |
Legal framework: eIDAS and Law 6/2020 in Spain
eIDAS Regulation (EU 910/2014) regulates qualified time stamps in Articles 41 and 42.
Article 41 establishes that a qualified time stamp cannot be rejected as evidence in judicial or administrative proceedings simply because it is in electronic form.
In Spain, Law 6/2020 on trust services complements eIDAS and sets the framework for national qualified providers supervised by the Ministry of Economic Affairs.
What a qualified time stamp actually proves
A qualified time stamp proves three things simultaneously and verifiably.
That the document existed at the stated date and time. That the content has not changed since that moment (integrity). That the time source comes from a reliable system (generally synchronised with UTC through national metrology laboratories).
This triple certification turns the stamp into a probative argument that is very difficult to challenge in court.
When it is mandatory and when it is advisable to add it
Regulations require qualified time stamps in specific scenarios: electronic invoicing for certain cases, electronic court records, public contract registers and systems where the date of submission determines rights or deadlines.
Beyond legal obligation, it is advisable whenever the risk of litigation is high or when the recipient may deny having received a communication on a given date.
Long-term service contracts, termination notices, unpaid debt claims and disciplinary notifications are cases where the time stamp reinforces the probative position of the sender.
Three situations where the absence of a timestamp creates real risk
A digitally signed contract without a qualified stamp can be challenged if the other party claims the signature did not exist before a key date.
A delivery receipt without a reliable time mark only proves the message arrived, not when; in limitation or expiry periods, that detail is decisive.
An internal communication about business decisions without a stamp cannot protect the company if an employee disputes the chronological sequence of events.
Timestamping in certified communications
At Legalpin, every certified email and every buromail includes a time stamp backed by a QTSP.
The record we generate contains the message hash, the time stamp and the qualified provider’s signature, forming an evidence package that can be presented directly in a proceeding without additional expert reports.
The Legalpin API allows time stamping to be integrated into automated workflows: contract platforms, CRMs, document management systems or debt collection tools that need to certify when each notification was sent.
Timestamping and electronic signature: how they complement each other
The electronic signature proves the signer’s identity and their intention to accept a document.
The time stamp proves when that signed document existed and that it has not been altered since.
Combining both, as Legalpin enables in its notify-then-sign flows, creates a record where neither the identity, nor the content, nor the date can be challenged independently.
Checklist for a record with documented temporal integrity
Use a QTSP from the European trust list to issue stamps, not an internal solution without external audit.
Keep the complete RFC 3161 token, not just the visible date; the token contains the hash and signature that allow independent verification years later.
Bind the stamp to the specific document: a generic session stamp does not protect a particular document in the same way as a stamp over the exact file hash.
Document the chain of custody: who sent it, to which system, when the token was received and where the record is stored. This traceability is what convinces courts.
Apply certified SMS as a parallel channel when the recipient is more responsive on mobile: the time stamp also covers the SMS send, closing the record through a dual channel.
Frequently asked questions
Is a qualified time stamp the same as a qualified electronic signature?
No: they are two distinct trust services under eIDAS.
The qualified signature identifies the signatory and binds their intention. The qualified stamp certifies the date and integrity of the data without needing to identify a signing person. They can be used together or separately depending on the case.
How long is a time stamp valid?
The stamp itself does not expire, but the TSA certificate that signed it has a lifespan. For long-term records, the recommended practice is to renew the stamp before the issuing certificate expires, applying a new stamp over the whole previous record.
Can I use a time stamp from my internal server in litigation?
With difficulty: an internal server is not a recognised trust authority, so the opposing party can challenge the reliability of the time source. For fully guaranteed evidence, use a QTSP from the EU trust list.
Does timestamping protect against content forgery?
Yes, with a nuance: the stamp protects the hash of the document at the moment of stamping. If the original document is altered afterwards, the hash will not match and the stamp will reveal it. But if the document was falsified before stamping, the stamp certifies the existence of that falsified version, not the original.
Does Legalpin use time stamps in all its certified services?
Yes: both certified email and buromail and certified SMS include time stamping backed by qualified trust providers. The record Legalpin generates can be presented directly in judicial or administrative proceedings as evidence of sending, content and date.
General information only; this does not constitute individualised legal advice.
