Euribor September 2026 at 3.247%: How much your variable mortgage increases

Key data

The one-year Euribor stands at 3.247% in September 2026, according to the Bank of Spain Resolution published on October 2, 2026. This figure is directly applied to the annual or semi-annual revision of variable-rate mortgages in Spain, affecting millions of families and the financial planning of companies with real estate financing. The publication is made in accordance with Circular 5/2012 of the Bank of Spain, which requires the monthly publication of these official reference indices.

What does this regulation establish?

The Bank of Spain publishes each month the official reference interest rates for the mortgage market. These indices are the only valid ones for revising variable-rate mortgages in Spain. Below are all the data published for September 2026:

Note on Mibor: Mibor coincides with the annual Euribor (3.247%) but only maintains official validity for mortgage loans formalized before January 1, 2000. If your mortgage is after that date, the applicable index is Euribor.

Inverted €STR curve: The €STR shows an inverted curve: the weekly term (2.440%) is higher than the annual term (2.034%). This reflects market expectations of rate cuts in the medium term, although the annual Euribor remains the dominant index in variable-rate mortgages.

Economic and operational impact

The annual Euribor figure of 3.247% is what is applied in mortgage revisions. Its direct economic impact depends on the outstanding capital and the spread agreed in each loan:

• Mortgages with annual revision: The payment is recalculated by applying the September 2026 Euribor plus the contract spread (typically between 0.50% and 1.50%).
• Mortgages with semi-annual revision: The Euribor of the reference month agreed in the deed is applied (May or November, in most cases).
• 5-year IRS at 3.450%: Relevant for companies with mortgage financing indexed to this rate or for interest rate hedging operations (swaps).
• €STR: Reference index for interbank operations and alternative financial products; its inverted curve may influence the hedging strategy of financial entities.

Who does it affect?

• Individuals with variable-rate mortgages indexed to Euribor: Any revision made using September 2026 as reference will apply 3.247%.
• Companies with variable-rate mortgage loans: Industrial warehouses, commercial premises or offices financed with variable-rate mortgages will see their payment revised with this figure.
• Financial entities: Must apply these indices in revisions and communicate them correctly to their customers in accordance with current mortgage regulations.
• Holders of mortgages prior to 2000: Their reference is Mibor, which in September 2026 coincides with annual Euribor: 3.247%.
• CFOs and financial directors: With exposure to variable real estate financing, this figure is key for treasury planning and interest rate hedges.
• Advisors and wealth managers: Must communicate this figure to their clients with mortgages pending revision.

Practical example

Suppose a variable-rate mortgage with the following conditions:

• Outstanding capital: €150,000
• Remaining term: 20 years
• Agreed spread: Euribor + 0.99%
• Reference index: Annual Euribor for September 2026 = 3.247%

The applicable interest rate after revision would be: 3.247% + 0.99% = 4.237%.

With this rate, the approximate monthly payment for €150,000 over 20 years would be around €930-940/month, depending on the amortization system and exact loan conditions. This calculation illustrates how a Euribor around 3.2% implies significantly higher payments than those in years of negative or near-zero rates (2020-2022).

For companies with a €500,000 variable-rate mortgage loan, the difference between a 2% Euribor and the current 3.247% means approximately €6,000-7,000 additional per year in interest, a relevant impact on the income statement that must be considered in financial planning.

What should mortgage holders do now?

1. Identify your mortgage revision date: Check in your deed when the rate is revised and which Euribor month is used as reference. If it is September, the applicable figure is 3.247%.
2. Calculate the impact on your payment: Add the September 2026 Euribor (3.247%) to your contract spread and recalculate the payment with the outstanding capital and term.
3. Evaluate the convenience of switching to a fixed rate: With the 5-year IRS at 3.450%, some banks offer competitive fixed rates. Compare the cost of subrogation or novation with potential savings.
4. If you are a company, review your interest rate hedge: With €STR showing an inverted curve and annual Euribor at 3.247%, discuss with your financial entity the contracting of a swap or rate cap if you have significant exposure.
5. Mortgages prior to 2000 (Mibor): The applicable figure is also 3.247%, since Mibor and annual Euribor coincide in September 2026.
6. Keep the official certificate: The Bank of Spain resolution published in the BOE on October 2, 2026 is the official document that certifies the applicable rate. Keep it for any claims or verification.

Official source

Consult complete regulation at official source

Disclaimer: This article is for informational purposes only 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-2026-20519