TAN (Tax Deduction and Collection Account Number) registration is a unique identification number issued by the Income Tax Department in India to entities responsible for deducting or collecting tax at source. TAN is mandatory for entities that deduct or collect tax under various provisions of the Income Tax Act, such as employers deducting tax from employee salaries, businesses making payments to contractors or professionals exceeding specified limits, and financial institutions deducting tax on interest payments. The registration process involves submitting an application to the Income Tax Department along with the required documents and fees. Upon approval, the entity receives a 10-digit alphanumeric TAN, which is used for filing TDS (Tax Deducted at Source) or TCS (Tax Collected at Source) returns, depositing tax with the government, and issuing TDS or TCS certificates to deductees. Compliance with TAN registration ensures adherence to tax laws and facilitates smooth tax administration and compliance.