Tax Deduction Account Number or Tax Collection Account Number or TAN is a unique ten digit alpha-numeric number issued by the Income-tax Department.  For Business entities and other types of entities to deduct tax at the source while paying rent, salary, commission, contract etc., TAN is mandatory. Each assessee, liable to deduct TDS, shall mandatory to quote the TAN in all TDS/TCS Returns, TDS/TCS payments, Annual Information Return, TDS/TCS certificates and other communications regarding TDS with Income Tax Department.  Non quoting of TAN number in TDS return would attract a penalty of Rs. 10,000/-