TAN stands for Tax Deduction and Collection Account Number, allotted by Income Tax Department (ITD) of India. It is compulsorily required to all the persons who are accountable for Tax Deduction at Source (TDS) or Tax Collection at Source (TCS) on behalf of the income tax department. The deductor is required to quote TAN number in every correspondence related to TDS or TCS. Failing to apply for TAN or not quoting the same on the specified documents attracts a penalty of Rs 10,000. TAN, once issued, is valid for lifetime. For obtaining TAN, it may take 5-10 working days, from the time of submission of application and supporting documents.