Guide
E-invoicing and Verifactu in Spain: what your software needs
Spain is moving toward mandatory business-to-business e-invoicing and toward billing systems that cannot be tampered with (known as Verifactu, under the anti-fraud rules). For many companies this is not paperwork: it is a requirement their current software may not meet. This guide translates the regulatory part into what actually matters —what your system has to do— without dragging you through tax jargon.
By Miguel Alejandro Hayes· Founder, Hayes Projects· with Claude (AI)
What is changing (no jargon)
Two things at once. First: business-to-business (B2B) e-invoicing is becoming mandatory in phases —moving from loose PDFs to structured invoices that systems read automatically. Second: billing programs must guarantee that records cannot be altered or deleted without a trace and, in the Verifactu model, be able to report to the Spanish tax agency.
Exact deadlines depend on your company size and have been postponed. Do not trust a date from memory: confirm it with your advisor. What does not change is the direction —toward structured, traceable, verifiable invoicing.
What this means for your system
Your billing software has to be able to: issue in the structured format the rule requires, keep a tamper-proof record of each invoice (with its hash and chaining), and —depending on the model— communicate with the tax agency. If you invoice today with a spreadsheet, a Word document or a tool that ignores this, that is the problem.
The real risk is not just the fine: it is discovering at the last minute that your system does not comply and having to replace it in a rush. Cheap and calm is having the system ready before your deadline arrives.
How we approach it
If you use a standard billing tool that is already adapting, often the right move is to stay there —not everything needs custom development. We come in when your invoicing lives inside a system of your own or mixed into your operation (orders, projects, subscriptions) and that system has to comply and integrate without duplicating work.
We are not tax advisors: "what the law requires for your case" is theirs. Ours is "how your software complies" —designing or integrating it so structured invoicing, the tamper-proof record and reporting happen automatically, not by hand.
An honest note: I wrote this with AI’s help. I used it to organize the research and tighten the prose, then reviewed, corrected and signed off on every line myself. Which is, more or less, the whole point: AI speeds up the draft — the judgment and the responsibility stay mine.
Frequently asked
Does Verifactu force me to change software?
+
Only if the one you use does not guarantee tamper-proof records and the format/reporting the rule requires. Many standard tools are adapting; the problem is usually spreadsheets or unprepared in-house systems.
What is the deadline?
+
It depends on your company size and has been postponed. Do not rely on a date from memory —confirm with your advisor. The direction (structured, traceable invoicing) is firm.
Will you tell me if I am legally compliant?
+
No, that is your tax advisor. We make sure your software does what the rule requires: structured format, tamper-proof records and integration with your operation.
About the author
Miguel Alejandro Hayes — Founder, Hayes Projects
Economist and essayist turned developer. He founded Hayes Projects, a Miami venture studio and custom software lab, to build software that ships, scales and solves real problems.
Meet the founder→Co-author (AI)
Claude — Anthropic’s AI assistant
Anthropic’s AI model. It helped organize the research, structure the draft and tighten the prose. Every claim was verified and signed off by a human.
Does your invoicing live inside an in-house system? Book 20 minutes and we will check whether it is ready for what is coming.
Book 20 min — no pitch →Prefer email?
Leave your email and we'll reach out with an idea for your case.
No obligation. No spam — just one useful, concrete reply.
We use first- and third-party cookies (Google Analytics and Google Ads) to measure traffic and improve the site. You can accept or reject them. Learn more