The tax identification number (also called personal identification number, IdNr. or tax ID) has life-long validity and consists of 11 digits. Every person registered in Germany automatically receives a tax identification number. You can find it on your income tax assessment note or on the income tax notification of any year, but not on your monthly pay slip. Also don’t confuse this number with the eTIN! In case you really can’t find your tax ID anymore, you can use this form to request the number to be send to you via mail - it may take up to four weeks