Since 2008, every German citizen is in possession of a tax ID. You will have received this 11-digit number in a letter from the Federal Central Tax Office. The number can be found in large at the top right of the letter. If you aren’t in possession of this document, you can also find out your number at your local town hall. It's important that employees enter their tax ID and not their tax number. If you are not registered in Germany but receive income, you should contact the competent tax office. This applies for your tax ID at the BZSt.