If a customer calls their bank in Basque and the agent does not understand the language, what happens? Until now, financial sector regulation required institutions to respond to written complaints in the same language in which they had been submitted. It was a limited right and relatively easy to manage. Law 10/2025 significantly expands this right, with much broader practical implications for customer service teams.

This is currently one of the areas with the highest level of interpretative ambiguity, but precisely for that reason it deserves detailed analysis: financial institutions need guidance in order to start taking action.

What Already Existed: The Right to Receive a Response in the Language of the Complaint

Sector-specific regulation already established that customers have the right to submit complaints in Spanish or in any co-official language of the territory where they reside (Catalan, Basque, Galician, or Valencian) and to receive the response in that same language. This right applied to formal written complaints managed under the regulatory framework supervised by the Bank of Spain, the CNMV, and the DGSFP.

To manage this requirement, many institutions relied on specialized teams or translation services. The volume was manageable because it was limited to a specific type of communication.

What the Customer Service Law Adds: Language Throughout the Entire Interaction

Law 10/2025 goes much further. Its approach is that linguistic criteria should not be limited to formal complaints: they must apply to the entire interaction with the Customer Service department, including phone calls, live chats, emails, messaging services, and any other communication channel.

If an institution operates in a territory with a co-official language, it must be able to assist and respond in that language whenever requested by the customer, both orally and in writing. Customer service teams must also be trained accordingly.

Articles 29 ter.2 and 29 septies.4 of the amended Law 44/2002 establish this linguistic framework. The regulation does not state that every call must be handled in a co-official language. It states that when a customer requests it, the institution must be able to respond. But that “must be able to” carries very specific organizational implications.

The Operational Challenge: People, Training, and Availability

Having agents capable of providing fluent support in Catalan, Basque, Galician, and Valencian across all shifts and all channels is not easy, especially for medium-sized institutions or national organizations whose customer service centers are located in a single site.

The market for professionals fluent in some of these languages (particularly Basque) is limited. Geographic dispersion of customers adds further complexity: an institution may simultaneously serve customers in the Basque Country, Catalonia, and Galicia, each with different language needs during the same working shift.

The law does not establish specific availability thresholds, but this does not exempt institutions from compliance. What it does require is a structural customer service model, not merely occasional solutions.

Can Technology Be the Solution?

The answer is nuanced but encouraging. The law does not rule out the use of language assistance technology or AI-powered real-time translation systems, provided that service quality is guaranteed. This opens the door to real-time support tools for agents who do not fully master the language: systems capable of transcribing and translating conversations, allowing agents to understand customers and respond coherently.

However, technology does not eliminate responsibility for service quality. If the system makes translation errors that affect the proper resolution of the request, responsibility still lies with the institution. In addition, the system must be auditable.

Callback as a Temporary Solution, Not a Structural One

If, at a specific moment, no agent is available in the requested language, offering a callback from a qualified agent may be a valid solution. But with the same limitations applicable to waiting-time KPIs: it cannot become the standard approach. The institution must be able to demonstrate that it has a structural model for providing support in co-official languages, and that callbacks are only used exceptionally.

The Risk of Inaction

Co-official languages are considered a high-priority issue by Consumer Protection Authorities, especially in Catalonia, the Basque Country, and Galicia. The likelihood of receiving a complaint or undergoing an inspection in this area is higher than for many other regulatory requirements, partly because it is a right that citizens know and value, and partly because it is relatively easy for inspectors to verify whether an institution can provide service in a co-official language.

Institutions operating in these territories should include this issue in their compliance risk map and develop an action plan supported by documented evidence: who provides support in each language, what training agents have received, how demand is managed when immediate availability is not possible, and what technology is used as support.

Consulting C3 and MST Holding actively participate in the UNE Committee responsible for defining the audit standard for the Customer Service Law and maintain ongoing contact with the AERC to communicate the sector’s concerns to the organizations responsible for clarifying them.

Resolution Deadlines for Complaints: The Financial Sector Moves from Two Months to One

If there is one aspect of Law 10/2025 that will directly impact the day-to-day operations of customer service teams in the financial sector, it is the new framework for complaint resolution deadlines. The maximum response time is reduced from two months to one. Half the time to resolve complaints, while maintaining the same quality standards in responses and with the obligation to document everything. For many institutions, this is not a minor adjustment: it is a complete process redesign.

However, there are important nuances. The Customer Service Law (Ley SAC) does not establish a single deadline for all complaints in the financial sector. Instead, it introduces a distinction by type of service, requiring each complaint to be classified from the very moment it is registered.

The New Deadline Framework

Once the law comes into force, financial institutions must manage complaints according to the following differentiated structure:

• General complaints: maximum of 1 month from the formal submission of the complaint until the reasoned response is communicated to the customer. This specific deadline applies to the financial sector under sector-specific regulations, which take precedence over the general Customer Service Law. For all other sectors, the general deadline remains 15 business days.

• Payment services (payments, transfers, cards): maximum of 15 days. The shorter deadline already established under PSD2 remains in place. In this case, sector-specific regulation is stricter, not more flexible.

Previous regulation treated complaints in a generic manner, with a single two-month deadline for all cases. The Customer Service Law breaks this uniformity and introduces the need to classify and categorize each complaint according to the nature of the service involved. This has a direct impact on management systems, workflows, and agent training.

Why Accurate Classification from the First Contact Is Essential

If the deadline for a complaint related to a bank transfer is 15 days, while a complaint regarding a life insurance product allows one month, the system must identify the type of complaint from the very first registration and activate the correct deadline counter. Without this automatic or guided classification, the risk of non-compliance increases significantly, especially during periods of high volume.

This requires reviewing intake forms, categorization systems, escalation workflows, and automatic alerts for the teams responsible for each type of complaint. An issue related to an unauthorized card charge cannot be managed under the same deadline structure as a complaint concerning mortgage conditions.

Correct classification from the start provides another key advantage: prioritization. In high-volume environments, understanding that some complaints must be resolved within 15 days while others allow one month enables a far more efficient distribution of workload.

The Real Impact on Internal Processes

Cutting resolution times in half without reducing response quality requires identifying the real operational bottlenecks. Based on Consulting C3’s experience working with financial institutions, the most common issues are:

• The number of internal escalations required to resolve a complaint, as each escalation adds delays.

• Dependence on other departments (product, risk, legal) to obtain the necessary information. If these departments do not operate under internal SLAs aligned with the new regulatory deadline, the Customer Service department will not be able to comply.

• Agents’ ability to draft high-quality reasoned responses without always depending on higher-level validation.

• Internal approval times for responses, especially in complex or high-value complaints.

Evidence and Documentation: What Regulators Will Require

Compliance alone is not enough: institutions must also be able to prove it. Companies must maintain clear records of the exact time each complaint was received, its classification, the applicable deadline, and the date on which the response was communicated. This documentary traceability is what protects institutions during inspections or in the event of direct customer claims.

One particularly sensitive point is the starting moment of the deadline. The law establishes that the countdown begins from the formal submission of the complaint. Does the customer receive an automatic acknowledgment with date and time? Does that acknowledgment specify the applicable maximum response time? These are questions that must already be answered before the regulation comes into force.

What Financial Institutions Should Be Doing Now

• Review the current complaint management process and identify where the greatest delays occur.

• Implement an automatic or guided complaint classification system by service type, activating the corresponding deadline from the first registration.

• Align the internal SLAs of support departments (product, risk, legal) with the new one-month regulatory deadline.

• Ensure customers receive an automatic acknowledgment including the start date and maximum response deadline.

• Review alert systems so teams are notified when a complaint is approaching its deadline.

The shift from two months to one is not impossible to manage, but it requires a deliberate redesign of processes. It is not enough to do the same work in less time: it must be done differently.

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