You can find your company's tax number in the upper left corner of your last tax assessment notice from the tax office or on the tax number notification letter from the tax office. You can also ask your tax advisor.
What does the tax number look like?
Depending on the federal state, the tax number has ten to eleven digits. You can recognize the tax number by the following format:
"12/345/67890" or "012/345/67890" or "012/3456/7890".
You can find an overview of the different formats of the federal states here: Where is my tax number? (https://www.elster.de/eportal/helpGlobal?themaGlobal=wo_ist_meine_steuernummer, see column "Standardschema der Länder")
Which tax number do I need for MY orderbird - my private or my business tax ID?
Please enter the tax number of your company. If you are a sole trader, you may have only one tax number because your private tax number coincides with your business tax number. If so, then enter this tax number. If you are not sure whether you have the correct tax number at hand, ask your tax advisor for help.
Please note: Please do not enter "the private tax number for now". You cannot change it later!
My tax number is not accepted!
The reason for this is probably the format. Find here how to fix it: Why does the online TSS not accept my tax number?