Input tax credit is not a deduction you compute. It is an entitlement you have to qualify for, and Section 16(2) sets four conditions that must all be satisfied before you may keep a single rupee of it. The word the section uses is that no credit shall be availed unless each condition is met. There is no partial pass.
What makes this section genuinely difficult in practice is not its length. It is that one of the four conditions is about somebody else’s behaviour.
The four conditions
One: you hold a tax invoice or debit note. Clause (a). Not a proforma invoice, not a delivery challan, not a quotation, not an email confirming the order. A tax invoice carrying the particulars required by Rule 46, including your GSTIN, spelled correctly.
The wrong-GSTIN case is worth pausing on because it is common in groups. If the supplier has billed a sister concern’s GSTIN, the credit belongs to that GSTIN and not to yours, regardless of which entity paid the bill or received the goods. That has to be fixed at the supplier’s end with a credit note and a fresh invoice. It cannot be fixed in your books.
Two: you have received the goods or services. Clause (b). The explanation to the clause covers bill-to-ship-to arrangements, so goods delivered to your customer on your instruction still count as received by you. Where goods arrive in lots, the credit arises on receipt of the last lot, not proportionately along the way.
Three: the tax has actually been paid to the government. Clause (c). Not charged on the invoice. Not collected from you. Paid, in cash or through a valid credit ledger, by the supplier.
Four: you have furnished the return under Section 39. Clause (d). Your own GSTR-3B.
And running alongside these, clause (aa) since 01/01/2022: the invoice must have been reported by the supplier in his GSTR-1 and communicated to you. In practice, this is what makes GSTR-2B the gate rather than a convenience.
The condition you cannot control
Read those four again and notice the asymmetry.
You can guarantee condition one by checking the invoice. Condition two by checking the goods receipt note. Condition four by filing on time. All three are inside your organisation.
Condition three is not. Whether the supplier discharges his liability is his decision, taken in his office, with his cash flow, and you will usually not find out that he did not until well after you have claimed the credit, paid the invoice in full including the tax, and closed the year.
This is the structural unfairness at the centre of GST input credit, and it is deliberate. The scheme puts the risk of supplier default on the recipient, on the reasoning that the recipient chose the supplier and can apply commercial pressure. Whether that reasoning is sound is a fair debate. That it is the law is not.
The practical consequence is that supplier compliance is a credit risk, not an accounts payable detail. It belongs in vendor onboarding.
What this means before you onboard a vendor
The cheapest time to deal with condition three is before the first purchase order, not after the first default.
- Check the GSTIN is active on the portal, and check the return filing history that the portal exposes. A supplier three returns behind today will be four behind when your invoice is due.
- Prefer suppliers who file monthly. A quarterly QRMP supplier is not a problem in himself, but if he does not use the Invoice Furnishing Facility, his invoices reach your 2B only at the end of the quarter, and your credit sits idle for up to three months.
- Put it in the contract. A clause making the final payment or the tax component conditional on the invoice appearing in your GSTR-2B is ordinary commercial practice now and is not usually resisted. It converts a tax problem into a payment term, which is a much easier thing to enforce.
- Track it monthly, not annually. A supplier who has stopped filing is a problem you want to find in month two, while you still have unpaid invoices as leverage, not in month eleven when you have paid everything.
The 180-day rule, which is the condition people forget
Buried in the second proviso to Section 16(2) and given effect by Rule 37 is a condition that is entirely within your control and is missed constantly.
If you have not paid your supplier the value of the supply plus the tax within 180 days of the invoice date, the credit you took has to be reversed. You add it to your output liability in the GSTR-3B for the period in which the 180 days expire, with interest under Section 50.
The relief is that this is not permanent. Once you pay the supplier, you take the credit back, and the reclaim is not subject to the Section 16(4) time limit. So the money is not lost. But the interest is real, and it accrues from the date the credit was originally taken, not from the date of reversal.
Three things about this rule regularly cause trouble.
Part payment triggers part reversal. Pay 60 per cent of an invoice and 40 per cent of the credit reverses.
Retention money counts. Contractors hold retentions for months by design, and the unpaid retention is unpaid consideration for this purpose. On long construction contracts this is the single largest source of Rule 37 reversals, and it is entirely predictable, which means it can be managed.
The clock runs from the invoice date, not the due date. Agreeing 120-day credit terms with a supplier does not extend the 180 days. It just leaves you 60 days of margin.
Related-party supplies without consideration, and supplies where the value is deemed under Schedule I, are outside the rule, since there is nothing to pay.
Section 17(5) sits on top of all of this
Clearing all four conditions in Section 16(2) is necessary but it is not sufficient. Section 17(5) then blocks certain credits outright, no matter how perfect the documentation.
Motor vehicles for passenger transport with up to thirteen seats, food and beverages, outdoor catering, club and health and fitness memberships, rent-a-cab, life and health insurance, works contract services for immovable property, goods lost or stolen or written off, and anything given as a gift or free sample. Each has its own carve-outs, and the carve-outs matter, but the default is that the credit is blocked.
The one that costs the most money in practice is works contract and construction of immovable property. On a factory expansion the blocked credit runs into serious numbers, and it needs to be in the project cost from the start rather than discovered when the credit is disallowed.
And then the time limit
Even a credit that satisfies Section 16(2) and survives Section 17(5) still has to be claimed inside the window in Section 16(4): by 30 November following the end of the financial year, or the date of filing the annual return, whichever is earlier. Miss that and the credit lapses. It does not carry forward.
That is a separate subject with its own traps, including the retrospective relief now in Sections 16(5) and 16(6), and it is worth reading separately.
A checklist you can actually run
Before you claim, for each invoice:
- Tax invoice in hand, with your correct GSTIN and Rule 46 particulars.
- Goods or services actually received, last lot included.
- The document appears in the GSTR-2B for the period you are claiming in.
- The credit is not blocked by Section 17(5).
- You are inside the Section 16(4) window.
And once a month, separately, run the ageing: every unpaid invoice crossing 180 days, reversed under Rule 37 in that month’s return.
Four of those five are yours to control. The one that is not, condition three, is the reason vendor selection under GST is a finance decision rather than a purchasing one.
