Mortgage interest rates May 2026: what variable mortgages pay

Key data

If you have a variable mortgage, this publication directly determines how much you will pay in your next review. The Bank of Spain publishes each month the official reference interest rates for the mortgage market, and those for May 2026 are already available in the BOE since May 21. The Resolution of May 20, 2026 contains the indices that banks and savings banks are obligated to use to calculate revised payments.

This is not a structural regulatory change, but rather the monthly update of the data that drives millions of mortgage reviews in Spain. Ignoring this publication or failing to verify that your entity applies it correctly could mean paying more than you should.

What does this regulation establish?

The Bank of Spain has the obligation to publish monthly the official reference interest rates for the mortgage market, in accordance with current regulations. This resolution fulfills that mandate for the month of May 2026.

The published indices serve as the calculation basis for the review of variable rate mortgage loans. Among them, the most relevant and widely used in Spain is Euribor, although the resolution includes other official reference rates.

Financial entities cannot choose which index to apply at their discretion: they are obligated to use the indices published in the BOE in their contractual reviews. This protects the consumer and guarantees transparency in the calculation of payments.

Economic and operational impact

The impact of this publication is direct on the household economy of variable mortgage holders and on the operational processes of financial entities.

For variable mortgage holders: the payment they will make in their next review depends on the value of Euribor or another official index on the reference date agreed in their contract. If the index has fallen compared to the previous period, the payment will fall. If it has risen, it will rise. The monthly publication in the BOE is the mechanism that gives legal validity to that calculation.

For financial entities: they have the operational obligation to incorporate the published rates into their calculation systems before processing the reviews for the period. Failure to comply with this obligation may result in customer claims and supervisory actions by the Bank of Spain.

Since the publication is monthly and cumulative, mortgage holders must identify which publication month corresponds to their contractual review date, as not all contracts use the same reference month.

Who does it affect?

• Holders of variable rate mortgages: any natural or legal person with a mortgage loan referenced to Euribor or another official index will see this data reflected in their next annual or semi-annual review.
• Financial entities (banks and savings banks): are obligated to apply these indices in the calculation of revised payments. They must incorporate the published data into their systems before processing the reviews for the period.
• Financial and mortgage advisors: need to know the published values to correctly advise their clients on the impact on their payments.
• CFOs and financial directors of companies with variable rate mortgage loans: must update their financial cost projections with the newly published indices.
• Real estate investors with variable rate financing: the cost of their mortgage debt will be recalculated based on these indices at the next contractual review.

Practical example

Suppose you have a variable rate mortgage with annual review in June 2026. Your contract establishes that the payment is recalculated using the Euribor from the month before the review, that is, May 2026.

The Euribor value that your bank must apply is mandatory and is the one published by the Bank of Spain in this Resolution of May 20, 2026, available in the BOE since May 21. Your entity cannot use a different value or one published by a source other than the BOE.

If your bank communicates the new payment to you and you want to verify that the calculation is correct, you must consult the resolution directly in the BOE and compare the applied index with the published one. In case of discrepancy, you have the right to claim before the entity and, if you do not obtain a satisfactory response, before the Bank of Spain as the supervisory body.

What should companies do now?

1. Identify your mortgage review date: review your loan deed to know when your next annual or semi-annual review occurs and which month of Euribor or other official index is used as reference.
2. Check the rates published in the BOE: access the Resolution of May 20, 2026 to know the official value of Euribor and other reference indices corresponding to May 2026.
3. Verify your financial entity's calculation: when you receive the new payment notification, check that the applied index matches the one published in the BOE. If there is a discrepancy, claim in writing.
4. Update your financial projections: if you manage variable rate mortgage loans in your company, incorporate the new indices into your financial cost forecast models for the next period.
5. If you are a financial entity: ensure that your calculation systems have incorporated the rates published in this resolution before processing the mortgage reviews for the corresponding period. Non-compliance may result in claims and supervisory actions.