Input tax credit entitlement requires prescribed tax documents, receipt, tax payment and timely return filing under GST. Every registered person is entitled to input tax credit for tax charged on supplies used in business, subject to prescribed conditions: possession of prescribed tax documents from a registered supplier, actual receipt of goods or services (including delivery to an agent), payment of tax to the Government or utilization of admissible credit, and furnishing of the prescribed return. Credit on goods received in instalments accrues on the last instalment; failure to pay the supplier within the statutory period requires reversal of input tax credit with interest, though credit may be reclaimed upon payment. Depreciation claimed on the tax component of capital goods precludes credit, and claims are time barred after the specified return deadline or annual return filing.