Short Answer

You must give your employer your Steuer-ID rather than your Steuernummer to avoid being placed in the wrong tax bracket. The Steuer-ID is your permanent personal tax identification number, while the Steuernummer is a local office number used only for freelance work or filing.

What Most Expats Don't Realize

You received your first paycheck and noticed hundreds of euros missing because you provided your freelance Steuernummer instead of your personal Steuer-ID to HR. Your employer's system rejected the local office code and automatically dropped you into Tax Class 6, the highest possible rate. You had to wait several months for HR to process a retroactive payroll correction (Rückrechnung), costing you a temporary loss of 400 € in disposable monthly income.

What To Do

  • Open the official letter sent to you by the "BZSt" (Federal Central Tax Office) 2–4 weeks after your registration.
  • Copy the 11-digit number located at the top right of that document.
  • "Hier ist meine Steueridentifikationsnummer für die Personalabteilung." (Here is my tax identification number for the HR department.) — email this statement along with the 11-digit code to your employer.

The Truth

Germany is transitioning to a single ID system, but the old local filing system is dying a very slow, analog death.