> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://help.taxx.lu/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# Where can I find my Luxembourg file number (NIF)?

The file number is assigned by the Tax Administration and does not change from one year to the next. You can find it on every correspondence from the Tax Administration (e.g., last year's tax statement) This is a 9 or 11-digit number.

If it is your first tax return, you will not have this number yet. In that case, leave the field blank.