GST & Input Tax Credit on Procurement in India: A Buyer's Guide

On business purchases in India, the GST you pay your suppliers is not a sunk cost — it's a credit you can set off against the GST you collect on your own sales. That's input tax credit (ITC), and for a buying team it's one of the largest, quietest levers on landed cost. The catch: ITC only flows if you meet *every* condition. Miss one — a wrong GSTIN, an unfiled supplier return, a blocked category — and the credit evaporates into real cash lost.

This is a buyer's guide to GST and ITC on procurement: how the mechanism works, the conditions you must satisfy, what's blocked, and how to protect your credit through the procure-to-pay cycle. For quick number-crunching, keep the GST calculator and TDS calculator handy.

How input tax credit works

Every registered business charges GST on its sales (output tax) and pays GST on its purchases (input tax). You remit to the government only the difference: output tax minus eligible input tax. So if you collect ₹1,80,000 of GST on sales and paid ₹1,10,000 of GST on inputs, you remit ₹70,000 — the ₹1,10,000 is your input tax credit.

This is why a procurement decision is never just about the sticker price. A vendor whose GST you *can* fully claim is cheaper than a slightly lower-priced vendor whose credit you'll lose — a difference best captured in total cost of ownership, not the quote.

CGST, SGST, and IGST

• Intra-state purchase (vendor and you in the same state): GST splits into CGST + SGST — e.g. 18% becomes 9% + 9%.
• Inter-state purchase (different states): the same total is charged as IGST — one 18% line.
• Credit ordering: IGST credit is used first, then CGST and SGST against their respective liabilities. The order matters for cash flow.

Place of supply drives which tax applies, so the vendor's state on your purchase order and invoice has to be right. Get it wrong and the credit type mismatches your liability.

The four conditions to claim ITC

Under Section 16 of the CGST Act, you can claim ITC only when all of these are true:

1. You hold a valid tax invoice (or debit note) with correct GST details and HSN/SAC codes.
2. You've actually received the goods or services — tie this to your goods receipt note.
3. The supplier has paid the tax to the government and filed their return, so the invoice appears in your GSTR-2B.
4. You've filed your own return and paid the supplier within 180 days (or you must reverse the credit).

Blocked credits (Section 17(5))

Some inputs are blocked — you pay the GST but can never claim it. Common ones for a procurement team:

• Motor vehicles for personal/passenger use (with exceptions for further supply or transport of goods).
• Food and beverages, outdoor catering, and club/health memberships (unless onward supplied).
• Goods or services for personal consumption.
• Goods lost, stolen, destroyed, or given as free samples/gifts.
• Works contract and construction services for immovable property (with carve-outs for plant and machinery).

Knowing what's blocked changes the real cost of a buy. A category where ITC is denied is effectively GST-inclusive in your books — model it that way in the landed cost calculator.

Reconciliation: protect what you've earned

Claiming ITC is one thing; *keeping* it through reconciliation is another. The discipline that protects your credit:

1. Match your purchase register to GSTR-2B every month — flag invoices the supplier hasn't filed.
2. Chase non-filing vendors before the return deadline, not after.
3. Enforce the three-way match — PO, GRN, and invoice agreeing is also your ITC evidence trail.
4. Pay within 180 days to avoid mandatory reversal.
5. Track blocked credits separately so you don't accidentally claim them.

TDS, TCS, and the rest of the deductions

GST sits alongside income-tax TDS and, in some cases, TDS/TCS under GST. On many B2B payments you must deduct income-tax TDS before paying the vendor — get the rate right with the TDS calculator. These don't affect ITC directly, but they're part of the same payment-stage discipline in the procure-to-pay cycle.

How procurement protects ITC by design

• Verify GSTIN at onboarding — and re-verify periodically, since registrations get cancelled.
• Prefer vendors with a clean filing track record — factor it into the supplier scorecard.
• Capture HSN/SAC and place of supply on the PO so the invoice reconciles cleanly.
• Keep a complete, matched document trail for every payment.

Procupy applies GST correctly at the PO and invoice stages — CGST/SGST/IGST by vendor state, HSN/SAC on every line — and enforces a three-way match before payment, so your ITC evidence is built automatically rather than reconstructed at filing time. See how that compares to enterprise suites like SAP Ariba, or read the full P2P process for the broader picture.