Knowledge

Signing on behalf of the owner: when does your power of attorney not cover the contract?

Anyone signing for an owner without the contract stating the basis of their authority delivers a document whose validity depends on later ratification — and a general power of administration covers less than most offices assume.

A keyholder, property manager or agent rarely signs for themselves. They sign for an owner who is in the Netherlands, Germany or England. In practice that happens on the strength of an e-mail, a management agreement or years of habit — and the contract says nothing about it. That is the problem.

Without authority the contract is void, unless it is ratified

No one may enter into a contract in the name of another without being authorised to do so or being their legal representative. A contract concluded without that authority is void, unless the person represented ratifies it.

Art. 1259 Código Civil

Note what that says: validity depends on an act that has yet to happen. Until the owner ratifies, there is no contract — and ratification is exactly what a dissatisfied owner will refuse. The risk then sits not with them but with the office that signed.

What the contract must carry

The phrase "acting on behalf of" is an assertion. What a counterparty, a gestoría or a judge needs is where the power of attorney can be found, so they can check that it exists and what it says. That is four pieces of information.

The name of the notary, as it appears in the deed
Their place of practice ("Notario de Alicante")
The date of the document
The protocol number — the reference under which the notary keeps the deed

A private power of attorney is valid too. Article 1280.5 CC lists the power of administration among the documents that "must" be recorded in a public deed, but it is settled case law of the Tribunal Supremo that this article does not impose a validity requirement: article 1279 CC gives the parties the right to demand formalisation, not a sanction of nullity.

Where it does make a difference: evidential weight against a third party — and here the tenant is that third party. Article 1227 CC: the date of a private document only counts against third parties from its entry in a public register, the death of a signatory, or its delivery to a public official. A tenant can therefore maintain that the power was drawn up later than it states. With a notarial deed that argument does not arise, and it can be verified with the notary.

The trap a template does not see

Article 1713 CC: a power granted in general terms covers only acts of administration. Acts of disposition require an express power. Letting counts as administration up to six years; beyond that as disposition — article 1548 CC applies that same boundary to letting by an administrator.

And here is the trap: where the landlord is a legal person, the mandatory extension under article 9.1 LAU runs to seven years. A general power of administration therefore does not cover that contract, even though it says "one year". The template notices nothing: the term you fill in is one year, and the extension is not in the contract but in the statute.

What this means for an office

If you sign for an owner that is a company, check whether the power expressly mentions letting — a general power of administration is not enough there.
If someone signs as "administrador mancomunado", then by definition two people sign. A single signature under that description is a contradiction within the document itself.
Put the four details of the power into the contract, even if you know them yourself. You are not writing for yourself but for whoever reads the document five years from now.
If the power is a private document, bear in mind that the tenant can dispute its date. That is no reason to refuse it, but it is a reason to know.

We do not assess powers of attorney. We cannot see whether a poder actually exists, whether it has been revoked, or whether it covers this particular act. What we do is make sure the contract carries the details that let someone else check, and warn where the law requires an express power.

Sources

Código Civil, art. 1259 — contracteren namens een ander zonder bevoegdheid
Código Civil, art. 1227 — datum van een onderhands stuk tegenover derden
Código Civil, art. 1279 en 1280.5 — vordering tot formalisering, geen nietigheid
Código Civil, art. 1713 — algemene volmacht omvat alleen beheershandelingen
Código Civil, art. 1548 — verhuur door een beheerder, grens van zes jaar
Ley 29/1994 de Arrendamientos Urbanos, art. 9.1 — dwingende verlenging tot zeven jaar bij een verhuurder-rechtspersoon

Verified on 2026-08-08.

Not personal legal advice This article sets out what Spanish law provides, with the source attached. It does not assess your own situation and does not replace a lawyer or gestoría. With a live dispute or a large financial interest, a lawyer belongs at the table — with this piece beside them.

Contracts that already get this right

ContractHost assembles Spanish rental contracts from a clause register that carries the law article and the verification date on every clause. When the law changes, the model changes.

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