Verifactu and blockchain: invoicing record integrity for the Spanish Tax Agency

Verifactu is the Spanish Tax Agency (AEAT) system that stems from the Anti-Fraud Law (Law 11/2021) and Royal Decree 1007/2023, requiring invoicing software to guarantee the integrity, preservation, traceability and inalterability of invoicing records.

After the postponement approved by Royal Decree-law 15/2025, the obligation applies from 1 January 2027 to corporate income taxpayers and from 1 July 2027 to everyone else, including the self-employed. Software vendors are already required to offer compliant systems.

What Verifactu requires

Each invoice generates an invoicing record that must meet several requirements:

  • A fingerprint (hash) of each record, chained to the previous record.
  • Inalterability: corrections are made with new records, never by overwriting.
  • A QR code on the invoice so the customer can check it with the AEAT.
  • A system event log and record retention.
  • Verifactu mode (submission to the AEAT) or non-Verifactu mode (with electronic signature and additional requirements).

Chaining: the same logic as blockchain

The hash chaining Verifactu requires is the principle blockchain is built on: each record includes the fingerprint of the previous one, so altering one breaks the whole chain after it. The difference is who stores the chain and who can verify it.

What a verifiable-evidence layer adds

Blockchain does not replace compliance with the AEAT technical specification; it complements it. Periodically anchoring record fingerprints on a distributed ledger with a timestamp provides independent, dated proof, verifiable by third parties, that the invoicing chain has not been rewritten.

It is especially useful for software vendors wanting to strengthen their responsible declaration, for companies in non-Verifactu mode that keep records in their own systems, and in audits or disputes where the state of the records on a given date must be proven.

How to integrate it without changing software

Integration is done via API: the invoicing software sends the fingerprint of each record or batch, and the evidence layer returns a verifiable proof. No tax data is exposed on the network, only cryptographic fingerprints.

Related guides