You will find your tax number at the top left of your last tax assessment from the tax office.  Alternatively, you can simply ask your tax advisor.

What does a tax number look like?

Depending on the 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".

Do I give my private tax number or that of my company when activating the Online-TSE?

Please enter the tax number of your company. If you are a sole proprietor ("Einzelunternehmer"), you may only have one tax number in certain cases, as your private tax number coincides with your business tax number. Simply enter this tax number. If you are not sure if you have the correct tax number at hand, please contact your tax advisor for assistance.