Spain's 3-minute law and the 400 prefix: what actually applies to a small business

The so-called 3-minute law is Ley 10/2025 on customer service, in force since December 28, 2025. Article 2 applies it to two groups. On one side, providers of basic services, whatever their size: water, gas and electricity, passenger transport, postal services, telecoms and financial services. On the other, any other company selling to consumers that, in the previous year, had at least 250 employees, more than 50 million euros in turnover or more than 43 million euros on its balance sheet (any one of the three is enough).

Those companies have until December 28, 2026 to adapt, and they're the ones that will have to answer 95% of calls in under three minutes on average (Article 10.3). A garage, a training academy or a neighborhood shop is outside it. Financial services are in, but they're governed by their own sector rules, and the law doesn't say which entities exactly it covers or mention insurance intermediaries. If that's your case, check with your advisor.

Not if your company is outside that law. The 400 range comes from a resolution published in the Spanish Official Gazette (BOE) on April 16, 2026, and its first section limits the obligation to companies covered by Ley 10/2025. The resolution gives six months from its entry into force, so from October 17, 2026 those companies can only make sales calls from numbers starting with 400, and those numbers can't be called back. The law generally gives twelve months to adapt; if your company is covered, confirm with your advisor which deadline applies to the 400 range.

We've seen it explained the other way round in more than one place, as if any small business calling its customers had to switch numbers. The resolution doesn't say that. As far as the number goes, if you call customers from your business landline or mobile, nothing changes.

The same Ley 10/2025 amended Article 21 of Spain's consumer law, which applies to any company selling to consumers, with no size threshold. Since December 28, 2025, if you serve customers by phone or electronically (a website chat, email, WhatsApp), you have to guarantee direct personal attention. A bot or an answering machine can help, but they can't be the only option.

The same article sets two more obligations. Customer service can't be used for commercial communications, and complaints must be answered as soon as possible and within 15 days at most. If you only sell to other businesses, this part of consumer law doesn't apply to you.

Check that customers can ask for a person at any point and that asking works: a keyword or a button that hands the conversation to someone in the business, with clear hours for when they'll reply. Since August 2, 2026, the assistant also has to say it's an AI in its first message, unless that's obvious.

And log the complaints that come in through the assistant, with their date, so none goes past 15 days unanswered. This is an explanation of the rules, not legal advice; if your case has any special twist, check with a lawyer.