Editorial: professional secrecy does not stay at the firm once the report reaches the client

This is an editorial by the AGENTE LEX newsroom. It expresses the portal's opinion.

A client commissions their lawyer to carry out a legal review before buying a company. The report points out risks, contingencies and possible breaches. The lawyer delivers it and the client keeps it in their files. Months later, the tax authority requires the client, not the lawyer, to produce that document.

Is it still protected by professional secrecy? Circular 1/2026 of the General Council of the Spanish Legal Profession says yes. The circular arose from a resolution of the Central Economic-Administrative Tribunal of 15 October 2025 and addresses exactly that scenario.

What the circular says

Its conclusions are clear:

• Professional secrecy covers the documents the lawyer prepares and delivers to their client, even when they are no longer in the lawyer's hands.
• The tax authority should not be able to obtain them from the client by means of a requirement, because that would empty the protection secrecy grants.
• The client can refuse to produce them by invoking professional secrecy, without this being considered a tax infringement.
• Only the client and the lawyer can invoke it. A third party who received a copy, such as the other party to a transaction, cannot.
• A lawyer who is consulted about a requirement must inform the client that the documents are protected, explain the options and consequences, and not cooperate in handing them over without express authorisation.

The circular itself warns that it is institutional guidance, not binding unless a rule says otherwise, although following it is considered good professional practice.

Why we think it is right

Secrecy protects the relationship, not the paper

Professional secrecy does not exist to protect a filing cabinet. It exists so that a person can tell their lawyer the whole truth and receive complete advice without fear that the advice becomes evidence against them. If the protection disappeared the moment the report crossed the firm's door, the client would have two bad options: not ask for the report in writing, or ask for it incomplete.

Neither improves compliance with the law. Frank legal advice is usually the fastest way for a company to correct what it does wrong.

The law already points that way

Organic Law 5/2024, on the Right of Defence, establishes in its Article 16 that communications between lawyer and client are confidential. The Code of Ethics of the Spanish Legal Profession, in its Article 5, establishes that the duty of secrecy remains even after the lawyer has stopped providing the services. Protection that strong makes no sense if it depends on where the document physically is.

It is not a shield for everything

The circular does not make every paper untouchable. It speaks of documents prepared by the lawyer within the advisory and defence relationship and delivered to the client. Accounting documents, contracts or the company's invoices remain what they are, even if a lawyer has reviewed them. And the protection does not extend to third parties who hold a copy.

That balance matters. Professional secrecy loses legitimacy when it is invoked expansively. The circular limits it well.

What remains pending

The circular is an interpretation by the legal profession, not a judgment. The underlying conflict, between the tax authority's powers of inspection and professional secrecy, will end up being resolved in the courts. Meanwhile, firms can do three things:

1. Identify advisory reports as confidential documents prepared within the engagement.
2. Explain to the client from the start that those documents are protected and what to do on receiving a requirement.
3. Document the engagement: a clear engagement letter helps prove the nature of the work. The Right of Defence Act allows the client to demand one, as we recall in our summary of the Organic Law on the Right of Defence.

A final note on technology. The same duty of secrecy requires checking what happens to those reports when they are prepared with cloud AI tools. The CCBE guide on generative AI explains it. Protecting secrecy against the tax authority and neglecting it with a technology provider would be a contradiction.

More editorials and opinion pieces in Opinion. If you want to sign an opinion piece, send us your proposal from the Write for us page.