Late payment interest (interés de demora) on Spanish mortgages

Banks make money when you pay. They make more money when you pay late. Late payment interest is the penalty for falling behind, and for decades banks set it at abusive levels until the law put a ceiling on it.

What it is

Late payment interest (interés de demora) is a surcharge the bank applies when you fail to pay your mortgage instalment on time. The bank charges a higher interest rate on the unpaid amount for each day of delay. It is separate from the ordinary interest rate on your mortgage and is always significantly higher.

How much they can charge

The Ley de Contratos de Crédito Inmobiliario (Mortgage Credit Contracts Act) of 2019 set a clear cap: late payment interest on mortgage loans cannot exceed the ordinary interest rate plus 3 percentage points. If your mortgage has a TIN of 2%, the maximum late payment rate would be 5%.

Before this law, banks routinely included late payment rates of 18%, 20%, or even higher. This was not an error. It was a strategy: they knew most clients would never read that clause, and if they ever needed it, the margin was enormous. Courts struck down these clauses case by case until the 2019 law settled the matter with a statutory ceiling.

If your mortgage predates 2019 and has a late payment rate above the ordinary rate + 3%, that clause is very likely void. You can challenge it.

What happens when you stop paying

The process is not immediate. It typically follows these steps:

1. First missed payment: the bank contacts you to remind you. Late payment interest starts accruing on the unpaid instalment.
2. Repeated missed payments: if you accumulate several months of arrears, the bank can declare the loan in "early maturity" (vencimiento anticipado) — demanding repayment of the entire outstanding principal at once. Under the 2019 law, triggering this requires at least 12 missed payments or 3% of the capital in the first half of the loan's life, or 15 missed payments / 7% of the capital in the second half.
3. Foreclosure (ejecución hipotecaria): if you do not pay or reach an agreement, the bank enforces the guarantee. This means seizure and auction of the property.

What the forums say

Missed payments come up more often than you might expect, and not always for dramatic reasons. Some users were late by a couple of days because of a bank direct debit issue and saw late interest applied. The bank does not distinguish between a technical error and genuine difficulty — it charges either way.

Others found clauses in their deed about late payment conditions they did not remember negotiating. Some contracts link non-payment to automatic cancellation of associated insurance policies, creating a cascade effect: you miss one payment, lose the discount, your rate goes up, and the next payment becomes even harder to make.

How to protect yourself

• Read your deed (escritura): find the late payment section and verify the rate does not exceed the ordinary rate + 3 points.
• Communicate early: if you know you will have trouble paying, contact the bank before you miss a payment. They can offer a grace period (carencia), term extension, or restructuring. Banks prefer negotiation to foreclosure.
• Know your thresholds: remember that early maturity requires at least 12 months of non-payment in the first half of the mortgage. A single late payment does not trigger it.

Key takeaway

Late payment interest is capped by law at your ordinary rate + 3%. If your deed says otherwise, it is challengeable. If you anticipate payment difficulties, talk to your bank before you miss a payment — preventive negotiation almost always produces a better outcome than reactive damage control.