The customer’s tax ID on the invoice
On a full invoice, a business customer appears with their tax ID. On a simplified invoice, the tax ID is needed if that person wants to deduct VAT. A private customer on a simplified invoice may not show one. You type the customer: the app does not look them up at the Tax Agency.
When it is required
Royal Decree 1619/2012 requires the recipient to be identified on a full invoice, with a tax ID when they are an entrepreneur or a professional. A simplified invoice may omit it, and the Tax Agency reminds you that, in order to deduct, it has to be completed with the tax ID and the address. A private customer on a ticket does not have to show a tax ID. Inventing one, or leaving another customer’s, spoils the invoice and the book.
- Full invoice to a business: with tax ID.
- Simplified invoice in order to deduct: with tax ID and address.
- Private customer on a simplified invoice: it may omit the tax ID.
You type it
In Factura Fácil the contact’s tax ID is what you type or what is already on the card you saved. The app does not query the Tax Agency census to fill in the customer. If the tax ID is wrong, the invoice comes out with that error.
Common questions
Does a private customer have to give me a tax ID?
On a simplified invoice, it is not required. If they want to deduct, then their tax ID and address are needed, or a full invoice.
Does the app check the tax ID with the Tax Agency?
No. It does not look it up at the AEAT. The figure is the one you leave on the customer.
Official sources
Informational text reviewed on 26 September 2026. It is not tax advice and does not replace the Spanish Tax Agency or your accountant. Deadlines, rates, and forms can change.