The tax agency's data, correct before you invoice
NIF/CIF validation against the AEAT at onboarding, intra-EU VAT checks against VIES, and the VeriFactu configuration ready before the first invoice.
What it does
A firm doesn't need its software to open a tax-agency portal. It needs the data it is about to invoice against to be correct before an invoice exists, and the compliance groundwork that is its own responsibility to be configured before it is needed.
That is precisely what the AEAT integration does. When you create a client, Mandato validates their NIF or CIF against the tax agency's service. If the client is a company in another member state, it also checks their intra-EU VAT number against VIES, the European register.
And on the compliance side, Mandato holds the firm's VeriFactu configuration: the electronic certificate, its expiry date, and the warnings that precede it. It is plumbing, it does not demo well, and it is what stops you discovering an expired certificate on the day it matters most.
How it works in Mandato
Validation happens at onboarding, not afterwards. You type the NIF or CIF and Mandato checks it before the matter and the invoicing exist. A mistyped identifier stops becoming, three weeks later, a wrongly issued invoice to a client who doesn't recognise it.
For intra-EU clients, the VIES lookup returns whether the VAT number is active and whose it is. A firm invoicing a German or Dutch company knows, before it raises anything, whether the reverse charge applies.
The electronic certificate is uploaded once and stored encrypted. Mandato watches its expiry and warns thirty, sixty or ninety days ahead, whichever the firm configures. It is not a feature that shines in a demo; it is the one that prevents a month of blocked billing.
All of it lives in the client record and the firm's settings, not in a separate module somebody has to remember to open.
Mandato is not an AEAT portal. It does not look up your tax obligations, it does not read your notifications from the agency, and it does not generate a fiscal calendar: those features are not built, and we are not going to describe them as though they were. It does not file tax forms either — not the 303, not the 111, not the 200. Mandato validates identifiers and holds your compliance configuration; tax work stays where it is today, and if that is Holded, we export there.
Frequently asked questions
Does Mandato show me my AEAT notifications?
No. That feature does not exist in Mandato. What it does is validate your clients' tax IDs with the official algorithms and check intra-EU VAT numbers against VIES.
Does Mandato file my tax returns?
No, and it isn't being built. Mandato records the firm's work and its billing; filing happens in your accounting software or through your adviser. We export to Holded.
What if mine is a tax practice? Is Mandato any use?
Yes, for the matter — not for the filing. A requerimiento, a set of alegaciones, a recurso de reposición or a claim before the TEAR are matters with phases, documents and deadlines counted in working days, and Mandato runs them the way it runs a civil procedure. It also runs retainers, which is how most tax advisory work is billed, VeriFactu-ready invoicing, and the portal where the client can see where things stand. What it does not do is the filing itself: the modelos are submitted where they are submitted today.
Is the tax-ID check real time?
Yes. It runs when the client is created, before the matter and the invoicing exist. An invalid CIF surfaces at onboarding, not on the first rejected invoice.
What happens when my VeriFactu certificate expires?
Mandato warns you as far ahead as you configure — 30, 60 or 90 days. The certificate is stored encrypted and its expiry is watched without anyone diarising it.