A purchase offer does not need an electronic signature to hold: under Belgian law the sale is formed by agreement on the property and the price, and an email is enough to carry that agreement. The question is therefore not validity. It is evidential: the day someone disputes it, what do you show?
What a qualified electronic signature is
The European eIDAS Regulation distinguishes three levels of electronic signature. The highest, the qualified signature, rests on a certificate issued by a qualified trust service provider and on an approved signature creation device.
Its consequence fits in one sentence: across the Union, a qualified electronic signature has the same legal effect as a handwritten signature. It cannot be denied legal effect in court on the sole ground that it is electronic. That is the level itsme uses for signing documents.
What itsme establishes at the moment of signing
Three things, and it is worth separating them:
- Who. The signatory identified themselves with a means verified when their account was opened, tied to their Belgian identity card and their bank. This is not an email address anyone can create.
- What. The signature seals the exact document presented. Changing one character afterwards breaks the seal, and verification says so.
- When. The timestamp fixes the moment of signing. On an offer with a short validity period, that is no detail: it decides whether the offer was still open.
What the signature does not say
This is the part people forget, and the part that causes disappointment.
A qualified signature does not establish solvency. It says nothing about the buyer's bank agreement. That is precisely the role of the financing condition, with its amount and its deadline, and not the role of the signature.
It does not establish the truth of the content. If the offer states a wrong figure, that figure is signed as written. The signature proves commitment, not accuracy.
It says nothing about the property: not that the seller owns it, not that it is free of occupation, not that it complies with planning rules. Those checks belong to the preliminary contract and the deed, at the notary's.
Finally, it does not replace advice: an offer signed with no suspensive condition is perfectly valid - and that is exactly the problem.
The log matters as much as the signature
In the disputes that surface, the signature is rarely challenged. What is challenged is something else: "I never received that offer", "it was never passed on to me", "it reached me after I had already accepted the other one".
Hence the second pillar alongside the signature: a timestamped log of what was passed on, to whom, and at what time. The seller sees each offer the moment it is signed; the agent keeps the proof that it did leave. The two protections go together - a perfect signature on an offer whose delivery nobody can prove solves only half the problem.
For the buyer, in practice
Signing with itsme from a phone takes under a minute and requires no extra app: it is the same application used for banking and government services. The trade-off is real, and worth saying out loud: a signed offer binds. The validity period and the suspensive conditions are the two protections to settle before signing, not after.