Three numbers, three different jobs. The German tax system gives you a Steuer-ID the moment you register as a resident, a Steuernummer once you start working for yourself, and a USt-IdNr if you ever invoice business clients in another EU country. They look similar, sound similar, and they all live in the same paperwork drawer — which is exactly why people end up putting the wrong one on their invoice.

Here is the practical version, ranked by how often each shows up in your week.

Short answer

Your Steuernummer goes on every invoice you write. Your USt-IdNr also goes on the invoice when you are billing a business in another EU country. Your Steuer-ID never appears on a business invoice — it is personal, not commercial.

That is the rule. The rest of this page explains why, and what to do when you only have one of the three.

What each number actually is

Steuer-ID — your personal tax ID

The Steueridentifikationsnummer (also written Steuer-ID, IdNr, or TIN) is an 11-digit number assigned to every individual resident in Germany. You get it once, you keep it for life, and it follows you when you move. The Finanzamt sends it by post within a few weeks of your Anmeldung.

It is used for things tied to you as a person: the income-tax statements your employer files, Kindergeld, your annual tax return, communication between your bank and the tax office. It is not a business identifier and does not belong on a B2B invoice.

Steuernummer — your freelance tax number

The Steuernummer is the number your local Finanzamt assigns to you (or to your business) when you register as self-employed via the Fragebogen zur steuerlichen Erfassung. It usually looks like 12/345/67890, and the exact format changes slightly between Bundesländer.

This is the number the Finanzamt uses to identify your tax case. Every invoice you issue must carry either this number or your USt-IdNr. If you move to a different Finanzamt's jurisdiction, your Steuernummer changes — your old invoices stay valid, but new ones use the new number.

USt-IdNr — your VAT number for EU trade

The Umsatzsteuer-Identifikationsnummer is your VAT identification number for cross-border business inside the EU. It looks like DE123456789 — country code plus nine digits. You apply for it free of charge through the Bundeszentralamt für Steuern (BZSt), or you can tick a box during the Fragebogen and the BZSt issues it automatically.

You need it if you sell services or goods to a business in another EU member state — that is how the reverse-charge mechanism works. You do not strictly need it if you only invoice German clients, but most freelancers apply for one anyway because clients occasionally ask for it as proof that you are a real business.

Which one goes on the invoice

Under §14 (4) UStG, every invoice must include either your Steuernummer or your USt-IdNr. You do not legally need both. In practice:

  • Invoicing a German client → Steuernummer
  • Invoicing a business in another EU country → USt-IdNr (and theirs, too — see below)
  • Invoicing a private individual outside the EU → Steuernummer
  • Invoicing a business outside the EU → Steuernummer

Many freelancers simply print both numbers on every invoice. That is fine. What is not fine is printing your Steuer-ID instead — or worse, alongside the others, where it gets mistaken for one of them.

Edge cases worth knowing

Reverse charge to an EU business. Your invoice must show your USt-IdNr and the buyer's USt-IdNr. The buyer accounts for VAT in their own country instead of you charging it. The required note is "Steuerschuldnerschaft des Leistungsempfängers". If you forget the note or the buyer's USt-IdNr is invalid, the reverse charge does not apply — and you may end up owing the German VAT yourself.

Kleinunternehmer (§19 UStG). If you are a small business, you can still apply for a USt-IdNr — and you should, if you ever invoice EU businesses. Your Kleinunternehmer status does not exempt you from the documentation rules for cross-border trade.

You do not have a Steuernummer yet. It can take the Finanzamt several weeks to issue one after you submit the Fragebogen. In the meantime, the common practice is to write "Steuernummer beantragt" on the invoice. It is not ideal, but it is accepted while you wait. Update the invoice (or issue a corrected one) once your number arrives.

Official wording

"Eine Rechnung muss […] die dem leistenden Unternehmer vom Finanzamt erteilte Steuernummer oder die ihm vom Bundeszentralamt für Steuern erteilte Umsatzsteuer-Identifikationsnummer enthalten."

— §14 (4) Nr. 2 UStG

In plain English: every invoice must show either the Steuernummer (assigned by your Finanzamt) or the USt-IdNr (assigned by the BZSt). One of them — at minimum.

What this means for you

You almost certainly have a Steuer-ID already; it arrived in the post after your Anmeldung. You probably have a Steuernummer if you have registered as self-employed. If you regularly invoice clients in other EU countries, applying for a USt-IdNr is a ten-minute form on the BZSt website and avoids awkward questions later.

Once the three numbers are in the right slots, the invoice itself becomes a one-decision job: who is the client, where are they based, and the right number — and the right legal note — should follow on its own.