Key data
| Regulation | Resolution of September 17, 2026, from the Bank of Spain, publishing certain official reference interest rates for the mortgage market |
|---|---|
| Publication | September 18, 2026 |
| Effective date | September 18, 2026 |
| Reference period | August 2026 |
| Affected parties | Holders of mortgages referenced to official Bank of Spain rates other than Euribor |
| Category | Real Estate |
| Legal basis | Circular 5/2012 of the Bank of Spain |
Holders of mortgages referenced to official Bank of Spain indices other than Euribor now have the data they need to calculate the revision of their payments. The Resolution of September 17, 2026 publishes the rates corresponding to August 2026, with immediate effect from its publication in the BOE on September 18, 2026.
Although these indices have minority use compared to Euribor, existing mortgage contracts that incorporate them as a reference are directly affected by these figures in each periodic review.
What does this regulation establish?
The Bank of Spain publishes monthly, under Circular 5/2012, the official reference interest rates for the mortgage market. This periodic publication does not introduce regulatory changes: its function is to provide the updated values of the indices that serve as reference for the revision of payments for certain mortgages.
For August 2026, the two published indices are as follows:
| Official index | August 2026 value | Scope |
|---|---|---|
| Average rate for mortgage loans over three years for acquisition of free housing | 3.134% | Spain |
| Average rate for mortgage loans for acquisition of housing between one and five years | 3.570% | Euro zone |
These indices are different from Euribor and apply only to mortgage contracts that expressly incorporate them as a reference. Their official publication in the BOE is the mechanism that enables financial entities and loan holders to calculate the corresponding payment revisions.
Economic and operational impact
The direct impact of this publication falls on holders of mortgages whose contract is referenced to one of these two official indices. In practice, this means:
- Payment revision: Financial entities use these values to recalculate the periodic payments of affected loans. The applicable rate in the revision is obtained by adding the spread agreed in the contract to the published official index.
- Difference between indices: There is a difference of 0.436 percentage points between the Spanish index (3.134%) and the euro zone index (3.570%). The applicable index depends exclusively on what is established in each holder's mortgage contract.
- Minority use: These indices affect a significantly smaller volume of contracts than Euribor, but holders of those mortgages should verify whether their next review coincides with the publication of this data.
From an operational perspective, financial entities must incorporate these values into their payment calculation systems for contracts referenced to these indices, ensuring that revisions are carried out with the official data published by the Bank of Spain.
Who does it affect?
- Holders of variable rate mortgages referenced to the average rate for mortgage loans over three years for free housing in Spain.
- Holders of variable rate mortgages referenced to the average rate for mortgage loans for housing between one and five years in the euro zone.
- Financial entities that manage portfolios of mortgage loans referenced to these official indices and must apply the new values in periodic reviews.
- Financial and mortgage advisors who advise clients with mortgages linked to official indices other than Euribor.
- Asset managers and CFOs of companies or funds with exposure to mortgage loans referenced to these indices.
Practical example
Suppose a holder with a variable rate mortgage referenced to the average rate for mortgage loans over three years for free housing in Spain, with a spread agreed in the contract of +1.00%.
With the data published for August 2026, the interest rate applicable in the next review would be:
| Concept | Value |
|---|---|
| Official index (August 2026) | 3.134% |
| Spread agreed in contract | +1.000% |
| Resulting applicable rate | 4.134% |
For a mortgage loan of €150,000 with a remaining term of 20 years, this resulting rate of 4.134% would translate into an approximate monthly payment of €920. The exact calculation depends on the outstanding capital, the remaining term, and the specific conditions of the contract, so it is recommended to request the updated amortization schedule from the financial entity after each review.
What should holders do now?
- Locate the reference index of your mortgage: Review your mortgage loan deed or latest payment receipt to identify whether your mortgage is referenced to the Spanish average rate (3.134%) or the euro zone average rate (3.570%), and not to Euribor.
- Check the date of your next review: If your payment review coincides with the period in which August 2026 data is applied, these are the official values your entity must use.
- Calculate the resulting rate: Add the published official index to the spread agreed in your contract to obtain the interest rate that will be applied in the review.
- Request confirmation from your financial entity: Ask your bank or savings bank to confirm in writing the rate applied in the review and that it matches the indices published by the Bank of Spain on September 18, 2026.
- Financial entities: Update payment calculation systems with the published values (3.134% and 3.570% depending on the applicable index) to ensure correct review of affected contracts.
Frequently asked questions
What is the official average mortgage rate from the Bank of Spain for August 2026?
The Bank of Spain has published two indices for August 2026: the average rate for mortgage loans over three years for acquisition of free housing in Spain stands at 3.134%, and the average rate for mortgage loans for acquisition of housing between one and five years in the euro zone reaches 3.570%. Both values were published on September 18, 2026 under Circular 5/2012 of the Bank of Spain.
How do I know if my mortgage uses the Bank of Spain's official indices instead of Euribor?
You should consult your mortgage loan deed, specifically the variable interest rate clause. If the reference index is the "average rate for mortgage loans over three years for acquisition of free housing" or the "average rate for mortgage loans in the euro zone," your mortgage uses the Bank of Spain's official indices. If the index is Euribor (usually 12-month Euribor), this data does not directly affect you.
How is my mortgage payment calculated with these official indices?
The interest rate applicable in the review is obtained by adding the published official index to the spread agreed in your contract. For example, if your mortgage is referenced to the Spanish index (3.134%) and you have a spread of +1%, the resulting rate would be 4.134%. With that rate, the exact payment amount depends on the outstanding capital and remaining term. Request the updated amortization schedule from your entity to know the exact payment.
How frequently does the Bank of Spain publish these mortgage reference rates?
The Bank of Spain publishes these official mortgage market reference indices monthly, as established in Circular 5/2012. Each month the data from the previous month is published. The resolution published on September 18, 2026 corresponds to August 2026 data.
What is the difference between the Spanish index (3.134%) and the euro zone index (3.570%)?
Both are official indices published by the Bank of Spain, but they measure different markets. The Spanish index (3.134%) reflects the average rate of mortgage loans over three years for free housing granted in Spain. The euro zone index (3.570%) reflects the average rate of mortgage loans for housing between one and five years across the euro zone. The difference between the two is 0.436 percentage points. The index applicable to your mortgage is the one expressly stated in your contract.
Official source
Consult complete regulation at official source
Notice: This article is purely informational in nature and does not constitute legal advice. For specific decisions, consult a qualified professional. Source: https://www.boe.es/diario_boe/txt.php?id=BOE-A-2026-19481
