Input tax credit is the mechanism that makes GST a tax on value added rather than a tax on tax — you offset the GST you paid on purchases against the GST you collect on sales, and pay only the difference. It's also where most businesses lose money, either by missing credit they're entitled to or by wrongly claiming credit they're not, then paying it back with interest. In 2026 the rules tightened sharply: the Invoice Management System now gates your credit, and the portal blocks ITC that isn't reflected in your auto-generated statement. Getting ITC right is now a monthly discipline, not a year-end clean-up.
Quick answer: To claim input tax credit (ITC), you must hold a valid tax invoice, have received the goods or services, the supplier must have paid the tax and filed their return, and the invoice must appear in your GSTR-2B (Section 16). With the Invoice Management System (IMS) live, only invoices you accept flow into GSTR-2B and become claimable. Certain credits are permanently blocked under Section 17(5) (motor cars, personal expenses, etc.), and ITC must be reversed if you don't pay the supplier within 180 days.
What is input tax credit?
When you buy goods or services for your business, you pay GST on them (input tax). When you sell, you collect GST (output tax). ITC lets you set off the input tax against your output tax, so you remit only the net. Example: you collect ₹18,000 GST on sales and paid ₹10,000 GST on inputs — you pay the government ₹8,000, not ₹18,000. ITC is the spine of GST; without it, tax would cascade at every stage.
The conditions to claim ITC
Under Section 16 of the CGST Act, you can claim ITC only when all of these are met:
- you hold a valid tax invoice or debit note;
- you have actually received the goods or services;
- the tax has been paid to the government by the supplier;
- the supplier has filed their GSTR-1, so the invoice appears in your GSTR-2B; and
- you have filed your own return.
The condition that trips most people is the GSTR-2B one (Section 16(2)(aa)): if the invoice isn't reflected in your auto-generated GSTR-2B, you cannot claim the credit — no matter how genuine your purchase or how valid your invoice.
IMS now controls your credit
The Invoice Management System has changed how ITC reaches you. Every supplier invoice lands in your IMS dashboard, and you Accept, Reject, or Pend it. Only accepted invoices flow into GSTR-2B and become claimable ITC. Two consequences:
- Inaction = acceptance. If you ignore an invoice, the system deems it accepted and it enters your credit — including any wrong or inflated invoice.
- Reject what doesn't match. A wrong invoice you fail to reject becomes a credit you'll have to reverse later, with interest.
With GSTR-3B already hard-locked and ITC hard-locking on the horizon, a weekly IMS review (before GSTR-2B generates on the 14th) is now essential.
Blocked credits under Section 17(5)
Some ITC is permanently barred, even on genuine business purchases, under Section 17(5). The main categories:
- Motor vehicles for personal use (with exceptions for transport businesses, driving schools, and further supply);
- Food and beverages, outdoor catering, club memberships, health services (unless used to make an outward taxable supply of the same kind, or where obligatory under law);
- Goods/services for personal consumption;
- Works contract and construction of immovable property (other than plant and machinery, and except where it's your business);
- Goods lost, stolen, destroyed, or given as free samples/gifts.
Claiming blocked credit is a frequent and costly error — verify eligibility before you claim.
The 180-day payment rule
If you claim ITC on a purchase but don't pay the supplier within 180 days of the invoice date, you must reverse that ITC (with interest), and you can re-claim it once you do pay. So ITC isn't just about having the invoice — it's tied to actually paying your supplier on time.
The time limit to claim ITC
You can't claim old credit indefinitely. ITC for a financial year must generally be claimed by the earlier of 30 November of the following financial year or the date of filing the annual return. Miss that window and the credit lapses. (Within IMS, invoices kept "pending" can be actioned in future periods, subject to this outer limit.)
Common mistakes that cost businesses
- Claiming on GSTR-2A instead of GSTR-2B. Only GSTR-2B is the valid basis now.
- Ignoring IMS. Unreviewed invoices are auto-accepted, pulling in wrong credit.
- Claiming blocked credits under 17(5) — cars, staff meals, personal items.
- Missing the 180-day payment rule and not reversing on time.
- No purchase-register reconciliation. Mismatches become locked-in errors.
- Claiming after the time limit. The credit simply lapses.
Worked example
A trader's books show ₹2,00,000 of ITC for the month. On reconciling against GSTR-2B, ₹40,000 of it relates to a supplier who hasn't filed GSTR-1 — so it's not in GSTR-2B and can't be claimed yet. Another ₹15,000 is GST on a company car used by a director — blocked under 17(5). So the trader's correct claim this month is ₹1,45,000, not ₹2,00,000. The ₹40,000 can be claimed once the supplier files (within the time limit); the ₹15,000 is gone for good. A business that claimed the full ₹2,00,000 would face reversal and 18% interest on the difference.
Checklist
- Confirm all four Section 16 conditions before claiming.
- Reconcile your purchase register against GSTR-2B every month.
- Review IMS weekly; reject or pend mismatched invoices.
- Exclude blocked credits under Section 17(5).
- Track supplier payments and reverse ITC unpaid beyond 180 days.
- Claim within the time limit (by 30 November of the next FY / annual return).
Frequently asked questions
What are the conditions to claim ITC? A valid invoice, receipt of goods/services, tax actually paid by the supplier, the invoice appearing in your GSTR-2B, and filing your own return.
Can I claim ITC if it's not in my GSTR-2B? No. Under Section 16(2)(aa), ITC is allowed only if the invoice is reflected in your auto-generated GSTR-2B.
What are blocked credits? Credits barred under Section 17(5) — such as personal-use motor vehicles, food and beverages, personal consumption, and certain construction — even on genuine business spends.
What is the 180-day rule for ITC? If you don't pay the supplier within 180 days, you must reverse the ITC (with interest) and can re-claim it after paying.
By when must I claim ITC for a year? By the earlier of 30 November of the following financial year or the date of filing the annual return.
This article is for legal awareness and education only and is not tax or legal advice. GST rules change frequently by notification; confirm current requirements on the GST portal or consult a qualified professional.