Validate Steuernummer

Validation of German Steuernummern. Written in TypeScript, exposed as ESM and UMD.

Installation

npm i validate-steuernummer

Or:

yarn add validate-steuernummer

Usage: Validation

import { validateSteuernummer } from 'validate-steuernummer'

// Providing a Steuernummer in the "Vereinheitlichtes Bundesschema zur
// elektronischen Übermittlung":
const err1 = validateSteuernummer('9/198/0/815/08152');
// err1 is `undefined`, because this is a valid Steuernummer from Bavaria

// Providing a Steuernummer in the "Vereinheitlichtes Bundesschema":
const err2 = validateSteuernummer('24 75 815 08154');
// err2 is `Die Prüfziffer der Steuernummer stimmt nicht`, because 4 is not the
// valid Prüfziffer for this Steuernummer from Bremen

// Providing a Steuernummer in the "Standardschema der Länder", and additionally
// passing the Bundesland that issued the Steuernummer:
const err3 = validateSteuernummer('24/815/08151', { bundesland: 'DE-NI' });
// err3 is `undefined`, because this is a valid Steuernummer from Niedersachsen

This library exposes a validateSteuernummer function that takes one or two arguments:

1. A string value containing (possibly) a German Steuernummer
2. Optionally: an options object

The function returns undefined if it deems the given value to be a valid Steuernummer, or an error string denoting why not.

Usage: Parsing

import { validateSteuernummer } from 'validate-steuernummer'

const {
  bezirksnummer, // '815',
  bundesfinanzamtnummer, // '2653',
  normalizedSteuernummer, // '2653081508158',
  pruefziffer, // '8',
  statePrefix, // '26',
  states, // 'DE-HE',
  unterscheidungsnummer, // '0815',
} = parseSteuernummer('053 815 08158', {
  bundesland: 'DE-HE',
});

This library exposes a parseSteuernummer function that takes one or two arguments:

1. A string value containing (possibly) a German Steuernummer
2. Optionally: an options object

The function throws an error if parsing fails. Note that this function does not further validate the given Steuernummer.

What's being validated?

This library checks that:

• The given string contains only digits, spaces (" "), and slashes ("/")
• The number of digits in the given string is between 10 and 13
• The state ("Bundesland") issuing the Steuernummer is known
  • Either, because the Steuernummer contains a valid state prefix (which means it must be of length >= 12)
  • Or, because the bundesland option was used to deliberately name the issuing state (this is useful when providing a Steuernummer in the commonly used Standardschema der Länder, which means it is contains 11 or 12 digits only)
• The state information contained in the Steuernummer matches the bundesland option, in case both are given
• The Bundesfinanzamtsnummer part of the Steuernummer references a known Bundesfinanzamt. This library checks against "GemFA 2.0" (GEMeinden und FinanzAemter 2.0) data, which lists 610 Finanzämter as of October 5th 2022.
• The Bezirksnummer part of the Steuernummer is valid (checking state-specific constraints)
• The Unterscheidungsnummer and Prüfziffer fulfill requirements specific to Nordrhein-Westfalen
• The Prüfziffer is valid. Relies on the "11er Verfahren", "2er Verfahren", or "Modifiziertes 11er Verfahren" depending on the issuing state. In the case of a Steuernummer from Berlin, validation passes if the Prüfziffer matches that calculated either for the Berlin-A or the Berlin-B scheme (cf. section 7.2 of this document).

For details about the validation requirements for Steuernummern, refer to this document.

Options

• bundesland: A string denoting one of the 16 German states using ISO 3166-2 notation. E.g., DE-BE for Berlin.
• errorMessages: An object allowing to overwrite the default (German) error messages returned. For example:

  validateSteuernummer(/* ... */, { errorMessages: {
    allowedCharactersError:
      'Please only use digits, spaces, dashes, underscores, or slashes'
  }});

Related libraries

• kontist/normalize-steuernummer for translating Steuernummern in the "Standardschema der Länder" or "Vereinheitlichtes Bundesschema" into the normalized "Vereinheitlichtes Bundesschema zur elektronischen Übermittlung"
• kontist/denormalize-steuernummer for translating a Steuernummer in the "Vereinheitlichtes Bundesschema zur elektronischen Übermittlung" into one in the "Standardschema der Länder" + the issuing state
• kontist/validate-steuerid for validating German Steuer-IDs (Steuernummer and Steuer-ID are not the same)

License

MIT