PAN (Permanent Account Number):
PAN is a unique 10-digit code issued by the Income Tax Department. It serves as a means of identification for taxpayers, and is mandatory for various financial transactions, including filing income tax returns, opening bank accounts, and buying/selling property.

TAN (Tax Deduction and Collection Account Number):
TAN is a 10-digit number issued to businesses and professionals who are required to deduct or collect tax at source. It is essential for individuals and companies that are involved in tax deduction or collection activities.

TDS (Tax Deducted at Source):
TDS is a system where tax is deducted at the point of income generation (like salary, rent, etc.) by the payer and is remitted to the government. TDS filing is mandatory for those who have deducted taxes, ensuring proper compliance and avoiding penalties.