For entrepreneurs, corporate entities, sole proprietors, and freelancers across India, managing income tax is not merely an annual year-end task. Under the Income Tax Act, taxpayers with substantial estimated earnings must follow the "Pay As You Earn" (PAYE) principle by remitting tax in installments throughout the financial year rather than as a single lump-sum payout during return filing. This system is known as Advance Tax. Failing to estimate, calculate, and deposit advance tax on time triggers mandatory penal interest under Sections 234B and 234C. This guide explains the calculation rules, statutory due dates, penalty mechanics, and step-by-step payment procedures