Input Tax Credit Rules Under GST: A Complete Guide

Input tax credit rules under GST allow a registered business to offset the GST it pays on its purchases against the GST it collects on sales — but only when four conditions in Section 16(2) are all satisfied, within a hard deadline set by Section 16(4). In 2026, the practical reality is stricter than the bare statute: your ITC is effectively capped by what shows up in your GSTR-2B, which means a supplier who does not file, or files late, can directly cost you credit you would otherwise be entitled to.

The four conditions under Section 16(2)

Section 16(2) sets out the baseline eligibility conditions for claiming ITC, and all of them have to hold at once — meeting three out of four does not entitle you to the credit.

• A valid tax invoice or debit note issued by a registered supplier.
• Actual receipt of the goods or services — credit cannot be claimed on an invoice for a supply that has not physically or contractually reached you.
• Section 16(2)(c): the supplier has actually paid the tax to the government, either in cash or through their own ITC. This is the condition that most directly ties your credit to someone else's compliance.
• You have filed your own return for the relevant period.

The 16(2)(c) condition is the one businesses most often overlook, because it makes ITC contingent on something the recipient does not control: whether the supplier actually remits the tax they collected.

The Section 16(4) time limit

ITC on an invoice or debit note for a financial year must be claimed no later than 30 November following the end of that financial year, or the date the annual return (GSTR-9) is filed for that year — whichever comes first. For invoices dated within FY 2025-26, that means the standard cut-off is 30 November 2026, unless the business files its GSTR-9 for that year earlier, which closes the window sooner.

Miss this window and the credit lapses permanently — there is no provision to claim it later. This is one reason regular reconciliation against GSTR-2B, rather than a once-a-year scramble, matters.

The 180-day payment and reversal rule

Claiming ITC does not end your obligations to the supplier. Under the proviso to Section 16(2), read with Rule 37, if you have not paid the supplier — value plus tax — within 180 days of the invoice date, the ITC you already claimed on that invoice must be added back to your output tax liability in the GSTR-3B for the period right after the 180 days expire. Interest under Section 50 (commonly cited at 18% per annum) applies to the reversed amount for the period it was wrongly held.

The credit is not lost forever: once you actually pay the supplier, you can re-avail it, and recent clarification indicates there is no separate Section 16(4) time limit on that re-claim. But the reversal itself is not optional, and it is easy to miss if accounts payable and GST compliance are not coordinating on aged, unpaid vendor invoices.

Blocked credits under Section 17(5)

Some categories of ITC are blocked outright, regardless of whether the purchase was for business use. These are not timing issues — they are permanent exclusions.

Why GSTR-2B and IMS now decide your ITC

The single biggest practical shift in how ITC works is that eligibility is no longer really about your own records — it is about what your suppliers report. GSTR-2B is the auto-generated, static statement of eligible ITC built from your suppliers' GSTR-1 filings, and the Invoice Management System (IMS) is the layer where you accept, reject, or leave pending each invoice before it counts toward your credit.

Because of this, a supplier who does not file their GSTR-1, files late, or has their GSTIN cancelled does not just create a paperwork headache — they directly keep an otherwise-legitimate invoice out of your GSTR-2B, which in effect denies the credit until the supplier's filing catches up. This is the structural reason vendor GST compliance has become a due-diligence item rather than a once-a-year afterthought. We cover the accept/reject/pending mechanics in detail in GSTR-2B and the Invoice Management System, explained.

Protecting ITC with supplier checks

Because so much of ITC eligibility now depends on a counterparty's own compliance, checking a supplier's GST status before — not after — you commit to a purchase is the cheapest form of protection available. A GSTIN verification lookup returns the supplier's current registration status, taxpayer type, and a full filing history with due dates, delays, and timeliness — enough to spot a chronically late filer or a cancelled registration before an invoice from them ever lands in your books.

It is also worth checking your own GST return due dates so that reconciling GSTR-2B against your purchase register is a routine step each period, not an emergency at year-end when the Section 16(4) window is about to close.

GET https://gstinapi.com/api/get-taxpayer-info/27AAACR5055K1Z7
X-API-Key: YOUR_API_KEY

// response includes filing history per return:
// { "returnType": "GSTR1", "period": "072026", "filingDate": "...",
//   "arn": "...", "status": "Filed", "delayInDays": 0, "timeliness": "On Time" }

Frequently asked questions