The 13-digit tax number for ELSTER
Updated: October 2026 · ~4 min read · eBilanz Fabrik (a tool, not tax advice)
In short: your usual German tax number (Steuernummer) looks different depending on the federal state — for example 133/8150/8159 in North Rhine-Westphalia. For electronic transmission to the Finanzamt it is converted into a unified 13-digit format (often called the “ELSTER format”). That conversion follows fixed per-state rules; you do not have to work it out yourself.
Why 13 digits at all?
The Steuernummer is issued by the tax offices of the federal states and historically has its own format in each state (different lengths and separators). For nationwide-uniform electronic processing via ELSTER and the ERiC interface, it is turned into a unified 13-digit number. This lets every transmission be assigned unambiguously to the correct tax office and tax account.
Example from North Rhine-Westphalia: the notice shows the number in the format FFF/BBBB/UUUP, and the state code 5 is put in front. In other federal states the number on the notice looks different, and the state code is a different one. Without guarantee.
What is the 13-digit number made of?
The 13 digits follow a fixed scheme. The first four digits are the federal tax-office number (Bundesfinanzamtsnummer) — a code for your federal state together with the number of your tax office. The fifth digit is always 0. Then come the district and distinguishing numbers, and the last digit is a check digit. In the example above: 5133 (tax office 133 in North Rhine-Westphalia), then the 0, then 8150 and 815, and finally the check digit 9. How long each part is on the notice, and which state code goes in front, is fixed per federal state.
Want to see the 13-digit form of your own number? Our free tax-number converter builds it from the number on your notice and your federal state — for all 16 federal states, right in your browser.
The Steuernummer is not the tax identification number
A common mix-up — the two numbers are easily confused:
| Feature | Steuernummer (tax number) | Tax identification number (IdNr) |
|---|---|---|
| Legal basis | Issued by the Finanzamt | Section 139b AO, Section 1 StIdV |
| Digits | per federal state (13 digits electronically) | 11 digits |
| Applies to | a tax account / company | a natural person |
| Changeable? | yes (e.g. on a move / change of office) | no, lifelong and constant |
| For the e-Bilanz? | yes — the Steuernummer | no |
For the e-Bilanz of your GmbH or UG, the Steuernummer is what counts — in 13-digit format when transmitted electronically.
Where do I find my tax number?
Your Steuernummer appears on every tax notice and usually on correspondence from your Finanzamt. Do not confuse it with the VAT identification number (USt-IdNr, starting with „DE“), which is used for intra-EU trade.
With eBilanz Fabrik you type your tax number exactly as it appears on your notice and choose your federal state. The software handles the conversion into the 13-digit transmission format. To the Finanzamt via ERiC in under 10 minutes, from 29,95 €.
Create your e-Bilanz →FAQ
What is the 13-digit tax number?
The unified format of your Steuernummer for electronic transmission to the Finanzamt via ELSTER/ERiC. It is formed by a fixed conversion from your state-specific tax number. Without guarantee.
Is the Steuernummer the same as the tax identification number?
No. The Steuernummer is assigned by the Finanzamt for a tax account and can change. The tax identification number under Section 139b AO is a lifelong, unchanging 11-digit number for natural persons. For the e-Bilanz the Steuernummer is what counts. Without guarantee.
Do I have to calculate the 13-digit tax number myself?
No. With eBilanz Fabrik you enter your usual tax number exactly as it appears on your notice and choose your federal state. The software handles the conversion into the 13-digit transmission format. Without guarantee.
How do I work out my 13-digit tax number?
From the tax number on your tax notice and your federal state. The conversion follows fixed rules per state; our free tax-number converter does it right in your browser. Without guarantee.
Is the tax number 11 or 13 digits long?
It depends on the form: your tax notice shows it in your federal state’s format, and the length differs by state — in North Rhine-Westphalia, for example, 11 digits (133/8150/8159). For ELSTER it becomes the unified 13-digit number (5 133 0 8150 815 9). Do not confuse it with the tax identification number, which also has 11 digits but is a different number (Section 139b AO, Section 1 StIdV). Without guarantee.
What is the ELSTER format of the tax number?
The unified 13-digit form: four digits of the Bundesfinanzamtsnummer (a code for your federal state and the number of your tax office), then always a 0, then the district and distinguishing numbers, and finally a check digit. 133/8150/8159 (NRW) thus becomes 5 133 0 8150 815 9. Without guarantee.
eBilanz Fabrik is a transmission tool and gives no tax advice. Information on number formats and the process without guarantee; the tax administration's specifications and the statutory rules govern (incl. Section 139b AO). Price: 29,95 € per filing, net plus 19 % VAT.