Input tax credit eligibility requires invoice, receipt, tax payment and return filing; non-payment triggers reversal with interest. Every registered person may claim input tax credit for tax on supplies used in business subject to conditions: possession of a tax invoice or prescribed document, receipt of goods or services (including deemed receipt), actual payment of tax to the Government in cash or by using admissible credit, and furnishing the statutory return. Credit for goods received in installments is allowed on receipt of the last installment. Credit is disallowed where depreciation was claimed on the tax component of capital goods, and claims are time-barred after the statutory return deadline. Failure by a recipient to pay the supplier within the prescribed period requires reversal of the input tax credit with interest, though credit may be restored upon payment.