Germany's Tax ID Number: How Americans Get the IdNr

Soon after you register your address in Germany, a letter arrives from the Federal Central Tax Office with an eleven-digit number on it. That is your tax identification number, the Steuerliche Identifikationsnummer, usually shortened to IdNr or Steuer-ID. Employers, banks, health insurers and the tax office will all ask for it.

For Americans used to a Social Security number doing many jobs, the German system can be confusing because several different numbers exist. This guide explains the IdNr, how you get it, what to do if it does not arrive, and how it relates to the other numbers.

What the IdNr is

Section 139a of the Fiscal Code requires the Federal Central Tax Office (BZSt) to give every taxpayer, and every other individual involved in an administrative procedure with a public authority, a single, permanent identifier for unique identification in tax and administrative procedures.

Section 139b adds two basic rules: a person may not receive more than one identification number, and each number may only be issued once.

The BZSt describes the IdNr as an eleven-digit number that contains no information about the person. It is permanently valid and does not change when you move, change your name or change your marital status. If you leave Germany and come back years later, you keep the same number.

How you get it: register your address

You do not apply for the IdNr. Section 139b(6) of the Fiscal Code requires registration offices to send the BZSt data on every resident registered with a sole or main residence, for the first assignment of the number. In other words, registering your address (Anmeldung) at the Bürgeramt triggers the process.

The BZSt then sends the number by post to your registered address. For data protection reasons, the BZSt states that it communicates the IdNr only by letter. This is one more reason to put your name on your letterbox right after you move in.

What the IdNr is used for

• Employment. Your employer needs it to retrieve your electronic wage tax deduction data (ELStAM), which the BZSt provides for employers to retrieve automatically.
• Tax returns. It identifies you on your income tax return. The BZSt notes that you can still submit a return without it, and your tax office knows this.
• Pre-filled returns. The number enables services such as pre-filled electronic returns.
• Banks. German banks commonly ask for it when you open accounts.
• Public payments. The BZSt can store your IBAN linked to the IdNr to allow payment of public benefits.

Use of the number and the stored data is limited to the purposes in Section 139b. Improper use is an administrative offence that can be fined.

What data is stored

Under Section 139b(3), the BZSt stores a defined set of data with the number, including identity details and information blocks under the Federal Registration Act. For wage tax purposes it also stores further registration data under the Income Tax Act, such as religious affiliation and marital status, and the IdNr of a spouse or partner.

When the letter does not arrive

Waiting is the most common problem. If you need the number urgently, for example for a new job:

1. Check that your registration was completed with your correct name and address.
2. Make sure your name is on the letterbox.
3. Look in other documents. The BZSt says the IdNr appears on income tax assessments, employment tax statements and some earlier BZSt letters.
4. Request it again using the BZSt's online input form or by letter. It will be sent by post to your registered address.

The BZSt can only re-send a number already assigned to you; it cannot create a new one.

Getting the number means you are in the German tax system

Receiving an IdNr does not by itself make you taxable, but the same step that triggers it, taking a home in Germany, usually does. Under Section 8 of the Fiscal Code, a person has a residence (Wohnsitz) where they hold a home under circumstances suggesting they will keep and use it. Under Section 9, a person's habitual abode is where they stay in a way that shows they are not there only temporarily, and a continuous stay in Germany of more than six months always counts from the start, with short interruptions ignored.

People with a residence or habitual abode in Germany are generally subject to unlimited income tax liability, meaning Germany taxes their worldwide income. For Americans this is the point at which the US-Germany tax treaty and foreign tax credits become relevant, because the US continues to tax you as a citizen.

Practical tips for the first months

• Keep the BZSt letter with your passport and registration certificate. You will copy it many times.
• Give the number to your employer before the first payroll run so that the right wage tax data is applied.
• When you move within Germany, register the new address. The IdNr stays the same, but letters from tax authorities follow your registration.
• When you leave Germany, deregister. Your number remains valid if you return.
• Never share the number in unsolicited emails or calls; the tax authorities do not ask for it that way.

The IdNr versus other German numbers

Tax number (Steuernummer). Issued by your local tax office, for example when you register self-employment. Freelancers put it on invoices. Unlike the IdNr, it is tied to the tax office that handles your file.

Business identification number. Section 139c of the Fiscal Code provides for a separate business ID, issued on request of the tax authority and starting with the letters "DE".

VAT identification number. Used for cross-border business within the EU. Not needed by most employees.

Social insurance number. A separate number used for social security, not for tax. Your employer will ask for it as well.

Your US tax ID still matters

Germany's IdNr does not replace your US Social Security number for US purposes. Under FATCA, foreign financial institutions report on accounts held by US account holders, and German banks will usually ask for your US taxpayer identification number when you open an account. Keep both numbers handy.

Quick reference

| Situation | Number you need | |---|---| | Starting a job | IdNr | | Filing a German return | IdNr, plus tax number once assigned | | Invoicing as a freelancer | Tax number | | Opening a German bank account | IdNr and US TIN | | US tax filing | US SSN |

Common questions

How do I get a German tax ID number? Register your address. The registration office sends your data to the Federal Central Tax Office, which posts the number to you.

Does my tax ID change if I move? No. The IdNr is permanent and does not change with a move, name change or marital status change.

Can I get my tax ID by email? No. For data protection reasons, the BZSt only communicates the number by letter to your registered address.

Is the IdNr the same as the Steuernummer? No. The IdNr is a lifelong personal ID. The Steuernummer comes from your local tax office and can change.