Input Tax Credit (ITC) Rules under GST — 2026 Guide

Published 10 May 2026 ~10 min read Compliance, GST

Input tax credit is where GST stops being a cost and becomes a flow. Get the rules right and every rupee of GST you pay on business purchases comes back as a setoff. Get them wrong — even by a misplaced invoice or a late supplier — and you pay tax twice plus 24 percent interest. This 2026 guide covers the four ITC conditions, the GSTR-2B matching regime, blocked credits under section 17(5), capital-goods rules, and the seven mistakes that quietly leak ITC every quarter.

What is input tax credit

ITC is the mechanism that lets a registered taxpayer set off GST paid on inputs against GST charged on outputs. It is the design feature that prevents tax-on-tax cascading. The arithmetic is simple — the eligibility rules are not.

Output GST liability       =  GST charged on sales
Input tax credit          =  GST paid on eligible purchases
Net GST to pay to govt    =  Output GST  -  Eligible ITC

If Output GST > ITC  →  pay the difference in cash
If ITC > Output GST  →  carry forward to next month (no refund except exports/inverted duty)

The credit ledger is maintained on the GST portal and split into IGST, CGST, SGST and Cess balances. Crucially, IGST can be used to pay any head, but CGST and SGST cannot cross-pay each other.

The four conditions in section 16(2)

Section 16(2) of the CGST Act lists four cumulative conditions. Miss any one and ITC is denied — no exceptions, no equitable relief.

GSTR-2B matching and the 2B-only rule

Since 1 January 2022, ITC can be claimed only to the extent it appears in GSTR-2B. This is the single biggest behavioural change in the GST regime — it shifts the compliance burden from buyer reconciliation to supplier diligence.

How GSTR-2B works:

• Generated automatically on the 14th of every month for the previous tax period.
• Includes invoices the supplier reported in GSTR-1 and IFF filings between the 12th of the prior month and the 11th of the current month.
• Provides a section-wise breakdown: ITC available, ITC not available, and ITC reversal.
• Frozen once generated — no further changes for that month.

If invoice in GSTR-2B  →  Eligible to claim ITC (subject to other conditions)
If invoice NOT in 2B   →  Cannot claim ITC, even with original invoice
                          Ask supplier to file/amend; will appear in NEXT 2B

The practical effect is that you should reconcile every month before filing GSTR-3B. Most accounting tools, including gstinvoice.app, pull GSTR-2B JSON and reconcile against your purchase register automatically.

Blocked credits under section 17(5)

Even if all four conditions are met, section 17(5) blocks ITC on specific categories. The list is exhaustive — if it's not on the list, the credit is allowed.

ITC on capital goods

Capital goods (assets capitalised in books, useful life > 1 year) get a friendlier treatment than under the pre-GST CENVAT regime.

• 100% ITC in the month of purchase — no staggering over years.
• Cannot also claim depreciation on the GST component under section 16(3) — you must choose. Most businesses choose ITC because the cash benefit is immediate.
• If sold within 5 years, you must pay either the unused proportion of ITC or the GST on the transaction value, whichever is higher.
• Common credit: if the capital good is used partly for exempt supplies (eg. interest income for an NBFC), proportionate ITC must be reversed annually under rule 43.

ITC on capital good sold within 5 years
Reversal = max(
    ITC claimed - (ITC × months_used / 60),
    GST on transaction value
)

Time limits and the November cutoff

You cannot claim ITC indefinitely. Section 16(4) caps the window for each financial year.

For invoices dated in FY 2025-26:
ITC must be claimed by the earlier of:
  - 30 November 2026
  - Date of filing annual return (GSTR-9) for FY 2025-26

After this date: ITC is permanently lost.

The 30 November cutoff was extended from "September" to "November" by Finance Act 2022 — it's still the most frequently missed deadline. Tools like our GSTR-1 vs GSTR-3B guide walk through which invoice gets reflected in which return so you can catch missed ITC before November.

Reversal and re-claim rules

Some scenarios force you to reverse ITC even after it has been claimed.

Rule 37: Non-payment to supplier within 180 days

If you don't pay your supplier within 180 days of the invoice date, you must reverse the ITC with interest at 18% from the date of original claim. You can re-claim it later in the month you actually pay.

Rule 42: Common credit on inputs/services

If you have both taxable and exempt outward supplies, reverse the proportion of common ITC attributable to exempt supplies, calculated annually.

Rule 43: Common credit on capital goods

Same principle as rule 42 but for capital goods, calculated over a 60-month useful life.

Section 17(2): Banking and financial services

Banks, NBFCs and insurance companies may opt to reverse a flat 50% of ITC instead of doing rule 42 calculations — useful when the exempt-supply ratio is too volatile to compute precisely.

Top 7 ITC mistakes

1. Claiming ITC before the invoice appears in GSTR-2B. The portal accepts it and your books look clean — until your reconciliation flags a mismatch and an officer issues a notice. Always file from GSTR-2B, not from your purchase register.
2. Missing the 30 November cutoff. A late-arrived invoice from March can still be claimed if you file October's GSTR-3B by 20 November and include it. Miss it and the ITC is gone permanently.
3. Forgetting rule 37. A 270-day payment cycle to a vendor silently builds up reversal liability. Many businesses discover this only during a 3B-vs-books reconciliation.
4. Claiming both ITC and depreciation on capital goods. Income tax auditors and GST auditors don't always speak to each other, so this can pass for a year — then both departments come knocking.
5. Treating section 17(5) as a heuristic. The list is exhaustive. If your purchase is not specifically blocked, the credit is allowed — even if it "feels" personal. Conversely, you cannot reason your way around a block by arguing business benefit.
6. Not maintaining inward supply mapping. When the officer asks "what taxable output did this hotel-stay ITC contribute to?" — you need a documented answer. Without it, the officer can apply rule 42 by force.
7. Claiming ITC on supplier's wrong tax head. If the supplier charged CGST+SGST when it should have been IGST, both you and the supplier need to fix it before the credit is usable. See our CGST, SGST, IGST guide for the decision tree.

Frequently asked questions

This article is informational and not professional tax advice. Statutory references are based on the CGST Act 2017 and IGST Act 2017 as amended through the Finance Act 2026. Always confirm rates and rules with your CA before filing.