Home Steuer-IdNr Germany
Germany Steuer-IdNr validator
How the Steuer-IdNr format works
- Format
- 11 digits
- Example
- 26954371827
Things to watch for
- 11 digits validated with the ISO 7064 MOD 11,10 check-digit algorithm over the first 10 digits
- Checksum only — a number passing this test does not confirm it is currently assigned or that the taxpayer is registered
- Not the same as the older Steuernummer (tax number), which has a different, region-specific format
^[0-9]{11}$The Steuer-IdNr (Steuerliche Identifikationsnummer) is Germany’s 11-digit personal tax ID, issued once by the Bundeszentralamt für Steuern (Federal Central Tax Office) and kept for life — it doesn’t change if you move, marry, or switch jobs. Every resident receives one automatically, usually by mail shortly after registering an address, and it’s what an employer, health insurer, and the tax office use to identify a person for wage tax, tax returns, and child benefit (Kindergeld).
It’s easy to confuse the IdNr with two other German numbers that look similar but aren’t: the Steuernummer, a shorter, region-specific number a local tax office assigns and can reissue if the holder moves, and the USt-IdNr (VAT ID), a business-facing number in the format DE plus 9 digits used for cross-border invoicing. The IdNr is the only one of the three that’s permanent and personal rather than tied to a tax office or a business.
How this validator works
This tool checks that the input is 11 digits and reruns the ISO 7064 MOD 11,10 check-digit algorithm over the first 10 digits to confirm the 11th matches, entirely in your browser with nothing sent to a server.
What a pass doesn’t tell you
A matching check digit confirms the 11 digits are internally consistent — not that the IdNr was ever actually issued or that the taxpayer is currently registered. Only the Bundeszentralamt für Steuern can confirm a specific IdNr is genuinely on file.
Scope: this page covers Steuer-IdNr format and check-digit validation only — not the Steuernummer, the USt-IdNr, or any registration lookup.
Content last reviewed 2026-07-23.
Steuer-IdNr FAQ
What is the Steuer-IdNr and who has one?
It's Germany's permanent 11-digit personal tax identification number, issued once by the Bundeszentralamt für Steuern to every resident and kept for life, regardless of address changes, marriage, or job changes.
Is the Steuer-IdNr the same as the Steuernummer or USt-IdNr?
No. The Steuernummer is a shorter, region-specific number your local tax office issues and can reissue if you move; the USt-IdNr is a business VAT number (DE plus 9 digits). The IdNr is the only one of the three that's permanent and tied to the person rather than an office or a business.
How does the check digit catch a typo?
The 11th digit is calculated from the first 10 using the ISO 7064 MOD 11,10 algorithm. A single mistyped or transposed digit almost always produces a check digit that doesn't match, which is exactly what this validator flags.