Law 1/2025 on Mediation and Measures to Improve the Efficiency of the Public Justice System, also known as the Mediation Act, establishes the Appropriate Means of Dispute Resolution Outside the Courts (MASC) and the requirement to use them in certain cases before filing a lawsuit. In this context, certified communications take on special significance , as we explain in this article.
The law indicates that it will be mandatory to try to reach a preliminary agreement in disputes related to:
- Commercial disputes.
- Mortgage contracts, loans and claims of abusive clauses.
- Consumer disputes.
- Horizontal property and urban leases litigation.
- And in collective labor disputes, to try to avoid strikes or more serious situations.
In other words, the courts will not admit lawsuits on matters included in the above categories if a mediation, conciliation or negotiation process has not been initiated beforehand through a neutral expert.
What happens to the deadlines when notice of an attempt at mediation is served?
And among the effects of the opening of this agreement process there is a very significant one, that of the interruption of the statute of limitations or suspension of the expiration of the actions from the moment that one of the parties notifies the intention to negotiate to the other. Specifically, the date of interruption will be the date of the attempt to notify the other party at the personal address or place of work, or through the electronic means of communication previously used.
How to Document an Attempt at Mediation Using Certified, Verifiable Communications
Authenticated communications are those that legally establish the sending, content, and receipt of a message, and are fully admissible as evidence in court. Under Law 1/2025, they serve as the mechanism for demonstrating that an attempt at mediation was made through a means that leaves a record. It is at this point where legal communications play a fundamental role due to their capacity to certify the content, the sending and receipt, the identities of the sender and the recipient, the time stamps, the opening of links, among other functionalities directly linked to their legal authenticity.
Its probative value is a guarantee and will be essential so that, in this case, the party seeking to initiate mediation can prove it, under a law that requires negotiation before suing. The courts will admit, in this regard, postal communications, by SMS, email, WhatsApp or online burofax, provided that they meet the necessary requirements.
From the MASC to the Lawsuit: Deadlines and Requirements Following the Mediation Attempt
The interruption of actions caused by the notice of intent to mediate will last until the date of signing the agreement or the end of the process without it. And in this case, the lawsuit may be filed within one year from the end of the unsuccessful negotiation. This period, one year, is also the one established for cases in which the notice of attempted conciliation has no response. Again, certification of communications may be essential.
The courts will admit the claim if they have a certificate attesting to the prior attempt to reach an agreement, which will be issued by the professional or institution that has concluded the process. If this requirement is not met, the claim may be inadmissible. And if one of the parties unjustifiably refuses to submit to mediation and later loses the dispute, it risks paying full costs, including those of the mediation.

Sectors and departments subject to Law 1/2025 on Mediation
This Law has a significant impact on several sectors and company departments. Here are some examples:
- Legal Departments and/or Law Firms: Companies should adapt their legal procedures to include mediation and alternative dispute resolution (ADR) mechanisms before going to court.
- Finance and/or collection departments: Claims for non-payment cannot derive directly in the filing of a lawsuit, but it is required that an attempt has been made to reach an agreement beforehand and also to be able to prove it with documents.
- Real estate servicers: In disputes involving condominium associations, they are required to reach a prior agreement before taking the matter to court.
- Human Resources: This department will have to manage and mediate internal labor conflicts using the new mediation mechanisms established by law.
Therefore, an important aspect to take into account is that the implementation of mediation processes may imply adjustments in budgets: more resources in the legal area or in the financial department, due to the obligation to reach prior agreements.
Given the potential costs that companies may face, documentary evidence that they have attempted to resolve the dispute through alternative means will be decisive. To this end, they should use solutions that provide proof of this fact and legal certainty through any means, such as certified fax, certified email, and even WhatsApp.
If you need more information on how to comply with the new regulations, you can see how we at MailComms digitize MASC processes.
For companies with a high volume of claims, certified email or certified SMS offer the same guarantees of authenticity as a burofax, with greater operational efficiency. MailComms Group, as a qualified QTSP under eIDAS, can advise you on the most appropriate solution based on the type of dispute and your usual channel of communication with the other party.
Frequently Asked Questions
What is MASC, and what does Law 1/2025 require?
MASC (Appropriate Means of Dispute Resolution) refers to mechanisms for resolving disputes outside the judicial process: mediation, conciliation, negotiation with a neutral expert, etc. Law 1/2025 on measures to improve the efficiency of the Public Justice Service, in effect since April 3, 2025, establishes that in certain matters, it is mandatory to attempt ADR before filing a lawsuit. The courts will not accept the lawsuit unless such a prior attempt is documented.
In what cases is MASC required before filing a lawsuit?
Law 1/2025 makes it mandatory to first attempt alternative dispute resolution (ADR) in: commercial disputes between companies; disputes over mortgage contracts, loans, and unfair terms; consumer disputes; disputes regarding condominium ownership and urban leases; and collective labor disputes to prevent strikes. The court will refuse to accept the complaint if it is not proven that an attempt was made to seek an alternative resolution in these matters.
How is an attempt at mediation documented for the court?
Proof of the attempt may be provided by a certificate issued by the professional or institution that concluded the mediation process. The critical element is the verifiable notification to the other party of the intention to negotiate, since it is from that moment on that the statute of limitations is suspended. This notification may be made via certified mail (burofax), certified email, certified SMS, or certified WhatsApp, provided that the method provides proof of sending, content, and receipt.
What happens to the statute of limitations during the mediation process?
From the moment one party provides the other with reliable notice of its intention to initiate a MASC, the statute of limitations is interrupted or the expiration of the claims is suspended. This suspension remains in effect until the date the agreement is signed or the process ends without an agreement. If the process ends without an agreement, the lawsuit may be filed within one year of the conclusion of the negotiations. The same one-year period applies when the notification goes unanswered.
Which sectors are most affected by the MASC requirement under Law 1/2025?
Those most affected are legal departments and law firms (which must incorporate the MASC into their procedures), finance and collections departments (claims for nonpayment require a documented prior attempt at settlement), servicers and real estate agencies (disputes involving condominium ownership and leases), and HR departments (collective labor disputes). All of them must provide documentary evidence of this attempt, which makes the use of certified, verifiable communications essential.
