The Euribor today rises to 2.977% and approaches 3% again in August.

Spanish regulations do not set a “day-to-day schedule” for the publication of the monthly average Euribor, but they do clearly establish who calculates it, how it is determined, and with what frequency it must be officially published. From this and the practice of the Banco de España, the procedures and deadlines can be described with reasonable precision.

1. Basic regulatory framework

The starting point is Article 27 of Order EHA/2899/2011, on transparency and protection of banking service customers:

• Paragraph 1 includes the “official interest rates”, among them the Euribor at one week, one month, three months, six months, and one year (art. 27.1.d).
• Paragraph 2 provides that “the official interest rates shall be published monthly by the Banco de España in the Official State Gazette and shall also be available on its website”.

This Order expressly authorizes the Banco de España to define the determination process of these official rates, which is developed in Circular 5/2012, of June 27, of the Banco de España, on transparency of banking services.

2. Calculation of the monthly average Euribor

Annex 8 of Circular 5/2012 (“Official reference interest rates of the mortgage market: definition and determination process”) specifically defines the Euribor:

• For each term (1 week, 1, 3, 6, and 12 months), the Euribor is defined as “the simple arithmetic monthly average of the daily values of the euríbor® reference index”, which appears in the annex of Implementing Regulation (EU) 2016/1368, issued in execution of Regulation (EU) 2016/1011 on benchmark indices.
• These monthly averages are calculated by the European Money Markets Institute (EMMI) and published on its website or other media.
• Substitution clause: “In the absence of such publication by EMMI, the Banco de España will calculate and publish the monthly averages.”

Consequently, the prior technical procedure consists of:

• Daily publication of the Euribor by EMMI on TARGET2 business days.
• Calculation of the monthly average (by EMMI or, subsidiarily, by the Banco de España) over those daily values of the already closed calendar month.

3. Publication by the Banco de España and the Official State Gazette (BOE)

With the calendar month closed and the monthly average already determined, two channels are activated:

• Dissemination by the Banco de España: the Banco de España communicates each month the monthly average of the Euribor and the rest of the official rates in press releases and on its website. These releases remind that the official rates “are valid from their publication in the BOE, which usually occurs a few days after their dissemination by the Banco de España” (see, for example, the releases “The Euribor stands at 2.855% in July, 0.776 points higher than a year ago” or “The one-year Euribor falls to 3.650% in June,” available on the Banco de España website).
• Official publication in the BOE: in compliance with art. 27.2 of Order EHA/2899/2011, the Banco de España sends these rates to the Official State Gazette, which publishes them in a specific section of official reference rates. This publication grants them legal validity as “official rates”.

4. Deadlines: what the regulation says and does not say

From a strictly regulatory point of view:

• Order EHA/2899/2011 requires that publication be “monthly”, but does not set a specific day (for example, “before the 15th of the following month”) nor a number of business days to send the data to the BOE.
• Circular 5/2012 details the calculation methodology (monthly averages over daily data), but also does not establish a specific deadline between the month’s close and publication in the BOE.

The only explicit temporal elements in the regulation are, therefore:

• The reference period: a calendar month of daily observations.
• The publication frequency: once a month.

From the Banco de España’s own releases, the usual practice can be inferred:

• The Banco de España usually disseminates the press release with the monthly average in the first days of the following month (for example, the 1st or 3rd of the month).
• The publication in the BOE normally takes place a few days after that dissemination by the Banco de España, without a maximum deadline set in the Order or Circular.

5. Operational summary

In summary, the procedures and deadlines according to the Banco de España regulations and its development are:

• Daily calculation of the Euribor by EMMI (EU framework: Regulation (EU) 2016/1011 and Implementing Regulation (EU) 2016/1368).
• Calculation of the monthly average over the daily values of the calendar month; if EMMI does not publish it, the Banco de España calculates and publishes it.
• Monthly dissemination by the Banco de España (press release and website), once the month is closed.
• Submission and official publication of the monthly average Euribor as an official interest rate in the BOE, at least once a month, usually a few days after the Banco de España’s release.

The law, in any case, does not specify a number of business days between the month’s close and the BOE publication: it only requires monthly publication and assigns the calculation and submission to the Banco de España.

According to current legislation, the Banco de España has a relevant role in the official dissemination of the Euribor and in the supervision of the use of benchmark indices by the entities it controls, but it is not the entity that calculates or administers the Euribor, nor is it the main supervisory authority of the index itself as a benchmark.

1. European framework: Regulation (EU) 2016/1011 and Law 6/2023

The Euribor is regulated by Regulation (EU) 2016/1011 on indices used as benchmarks in financial instruments and financial contracts (“Benchmark Regulation”). In Spain, this Regulation is mainly developed and specified through Law 6/2023, on Securities Markets and Investment Services, accessible in the BOE.

According to the excerpts of Law 6/2023 retrieved in the research:

• The CNMV is the competent authority in Spain for the application of Regulation (EU) 2016/1011 and may exercise all the powers that said Regulation grants to national authorities over benchmark administrators and over the supervisory framework of those benchmarks.
• “Without prejudice to the above, the Banco de España shall exercise the functions of supervision, inspection, and sanction relating to:
  • The obligations of Article 16 of Regulation 2016/1011 regarding supervised entities that contribute data to indices prepared by the Banco de España itself.
  • The obligations of Articles 28.2 and 29.1 of the Regulation, on the use of benchmark indices in certain financial contracts, with respect to entities subject to the Banco de España’s supervision in matters of transparency and client protection.

That is, regarding benchmarks, the Banco de España is not the general supervisor of the Euribor as an index; that function falls to the CNMV in coordination with ESMA. The Banco de España supervises how the entities it controls contribute (when appropriate) and use benchmark indices in their contracts with clients.

2. Calculation and administration of the Euribor

The analyzed documents and the practice described by the CNMV indicate that the Euribor is administered at the European level by the European Money Markets Institute (EMMI), under the umbrella of Regulation 2016/1011 and the supervision of the competent benchmark authorities, not by the Banco de España.

Therefore:

• The Banco de España does not set the Euribor methodology nor decide the panel of banks that submit data.
• It also does not calculate the daily index; the value is obtained from the contributions of the panel of entities and is disseminated at the European level.

Its role shifts, as we will see, to the ratification, statistical dissemination, and control of the use of that index in Spain.

3. Publication and “ratification” of the Euribor in Spain

The Banco de España’s own press releases, such as the one titled “The Euribor stands at 2.747% in April, 0.604 points higher than a year ago” (Banco de España), and various pieces from Demócrata, show a clear pattern:

• The Banco de España disseminates monthly the average Euribor at 12 months and other terms, presents it as an “official reference interest rate”, and explains that these rates “are valid from their publication in the BOE.”
• Demócrata’s articles repeatedly state that the Banco de España “ratifies that the Euribor closed” the month at a certain percentage and that the official monthly average is first published by the Banco de España and later appears in the Official State Gazette.
• Other pieces recall that the Euribor “is calculated daily (…) and in Spain is officially published in the Official State Gazette,” while the Banco de España supplies and certifies the data incorporated into the BOE.

In parallel, Order EHA/2899/2011 and Order ETD/699/2020, developed via Banco de España Circulars (such as Circular 5/2012 and 3/2021), empower it to define and determine the calculation process of the “official reference interest rates” used in mortgages, as well as to disseminate and submit them to the BOE. This includes the configuration of new indices based on the €STR, but does not alter the fact that the Euribor itself remains a pan-European benchmark administered by EMMI.

4. What the Banco de España can and cannot do regarding the Euribor

• It can do:
  • Supervise, inspect, and, if applicable, sanction Spanish credit institutions for the inappropriate use of the Euribor and other indices in their contracts, regarding transparency and client protection (Law 6/2023 in connection with Regulation 2016/1011).
  • Control compliance with the obligations of supervised contributors to indices it itself prepares.
  • Calculate and disseminate the monthly average Euribor and other official rates, and submit them for publication in the BOE, at which point they acquire official effects as reference rates for mortgages or other products.
• It cannot do:
  • Modify the formula or methodology of the Euribor.
  • Unilaterally set the daily or monthly value of the index, beyond its role of statistical collection and dissemination.
  • Act as administrator of the Euribor or as the main competent authority of the benchmark, functions assigned to EMMI and CNMV/ESMA under Regulation 2016/1011.

In summary, current legislation positions the Banco de España as supervisor of the behavior of entities that use the Euribor and as certifier and official disseminator of its monthly average, but not as a body that can design, control alone, or manipulate the benchmark index itself.

For a Spanish financial institution to grant variable-rate mortgages referenced to the Euribor, it is not enough to choose that index in the contract: it must comply with a set of legal and supervisory requirements derived from both Spanish and European law. The core lies in the regulations on transparency and protection of banking customers, the regulation of real estate credit contracts, and the rules on financial benchmark indices.

1. Basic regulatory framework

The main regulations setting the requirements are:

• Law 5/2019, on real estate credit contracts (text in BOE), which transposes Directive 2014/17/EU and establishes a reinforced regime of transparency, pre-contractual information, and responsible conduct for loans on residential-use properties.
• Order EHA/2899/2011, on transparency and protection of banking service customers (text in BOE), updated by, among others, Order ECE/482/2019, which regulates in detail how mortgage contracts must be structured, the treatment of variable interest rates, and official reference indices.
• Circular 5/2012 of the Banco de España (text in BOE), which develops the transparency obligations of banking services and responsibility in loan granting.
• Royal Decree 716/2009, on the mortgage market (text in BOE), which sets conditions for mortgage loans eligible for securitization and refers to reference indices of the Spanish mortgage market.
• Regulation (EU) 2016/1011 (Benchmark Regulation), integrated in Spain through securities market legislation (currently Law 6/2023), which regulates indices used in financial contracts, including the requirement that the Euribor administrator be authorized and supervised (at the European level, by ESMA).
• Law 10/2014, on the organization, supervision, and solvency of credit institutions (text in BOE), which frames the actions of entities under the supervision of the Banco de España.

2. Requirements regarding the reference index

Order EHA/2899/2011 requires that, in variable-rate loans, the interest rate be referenced to indices or official rates determined by regulation and published by the Banco de España. The text itself also foresees substitution solutions when the index ceases to be published, referring to Interest Rate Swap (IRS) rates that the Banco de España will also publish, with a spread calculated according to the contract.

In practice, to use the Euribor as a reference:

• It must be among the official indices admitted by the regulation and published by the Banco de España.
• The calculation formula of the applied rate (spread over Euribor, periodic revision, floor/ceiling limits) must be clearly stated in the contract.
• The entity must contractually foresee what happens if the index ceases to be available, coherently with the substitution rules and Regulation (EU) 2016/1011.

3. Transparency and information to the client

Law 5/2019 and Order EHA/2899/2011 impose reinforced information obligations:

• Standardized pre-contractual information: delivery of the European Standardized Information Sheet (FEIN), detailing the interest rate (fixed, variable, or mixed), the reference index, the spread, the APR, and representative examples.
• Specific warning about variability: Law 5/2019 requires that the borrower receive an additional APR illustrating the risks of a significant rate increase and be explained the impact on installments and total credit cost.
• Notarial control of material transparency: both Law 5/2019 and Order EHA/2899/2011 assign the notary the function of verifying that the client has received the information (including that related to the variable rate and reference index), understands its economic consequences, and that any floor/ceiling clause or limit to rate variation has been expressly explained.
• Registration of general conditions: the standard clauses of loans (including the Euribor + spread formula) must be registered in the Register of General Contracting Conditions and be accessible to clients.

4. Supervision and conduct of the entity

Besides being an entity authorized and supervised by the Banco de España under Law 10/2014, the entity offering Euribor-referenced mortgages must:

• Respect the principles of responsible lending and solvency assessment developed in Law 5/2019 and Circular 5/2012.
• Use only indices that comply with Regulation (EU) 2016/1011, i.e., administered by an authorized provider and included in the benchmark register.
• Comply with reporting obligations and information models to the supervisor provided in Banco de España Circular 4/2021 on transparency and client protection.

5. Practical summary

In summary, a Spanish entity can reference its mortgages to the Euribor if: (i) it is a supervised credit institution; (ii) the Euribor is among the official indices published and complies with the European benchmark regulation; and (iii) it incorporates in advertising, pre-contractual documentation, the deed, and general conditions all the required information about the variable rate, the risks of its fluctuation, and substitution rules, under the control of the notary and the Banco de España.