Is Excel an invoicing computer system?

What an invoicing computer system is

The regulation gives no list of programs: it defines the system by what it does. It is the set of hardware and software used to issue invoices. Nothing more, and nothing less.

That very broad definition is deliberate, and it explains everything else: had the law said «invoicing programs», it would have been enough not to call yours that. By defining it by function, anything you issue an invoice with falls inside.

Why Excel falls inside

A spreadsheet you fill in and save invoices with meets the definition point by point: it is a computer program and you use it to issue invoices. There is no exception for size, for volume or for how home-made the set-up is.

The thing is that a spreadsheet cannot meet the requirements, and it is not a matter of configuring it better:

• It would have to generate an invoicing record for every invoice, at the moment of issuing it.
• That record would have to carry a hash chained to the previous one's.
• The invoice would have to come out with its QR code.
• The system would have to carry a responsibility statement from whoever makes it, saying that it complies. If you built the spreadsheet yourself, you are the manufacturer.
• And it would have to guarantee that nobody can rewrite the past. In a spreadsheet you overwrite a cell and no trace is left: that is the exact opposite of what the rule demands.

The only way out: using no system at all

There is one exception and it is worth explaining properly, because it gets misread. Anyone who uses no computer system at all — invoicing from a paper book, by hand — falls outside the regulation.

But that is lost the moment you touch a program. Typing the invoice on the computer and then printing it already counts as using an invoicing computer system. The exception is for those who genuinely use nothing, not for those who use little.

How long you can carry on like this

Dates from the fourth final provision of Royal Decree 1007/2023, as worded by Royal Decree-Law 15/2025. They have been postponed twice: if you read any others, they are out of date.

Put another way: today, August 2026, your spreadsheet is still perfectly legal. What will not be legal is carrying on with it past your deadline.

What is worth doing in good time

The real work is not the change of format: it is the change of habit. Moving from a spreadsheet to a program means entering your customers, defining your numbering series and getting used to issuing from somewhere else. That goes well in January and badly on 30 June.

And there is one detail that saves you a nasty surprise: when you migrate, the old system has to be left unable to invoice. According to the Tax Agency's own criterion, once the obligation applies, keeping a non-adapted system that can still issue invoices is already an offence, whether you use it or not. Keeping it purely as an archive, to look up past records, is allowed, as long as you can show it is no longer used to invoice.