Input Tax Credit in 2026: The Rules That Trip People Up
Input Tax Credit, or ITC, is the mechanism that stops GST from becoming a tax on a tax. In simple terms, the GST you pay on your purchases can be set off against the GST you collect on your sales. Get it right and your working capital stays healthy. Get it wrong and you either lose credit you were entitled to, or claim credit you were not, and pay it back later with interest.
This guide walks through the four areas where we see people lose the most money. None of it is exotic. It is the everyday detail that quietly slips past busy business owners.
1. The time limit under Section 16(4)
You cannot claim ITC forever. For a given financial year, credit on an invoice must generally be claimed by the earlier of two dates: the return filing due date for November of the following year, or the date you file the annual return. Miss that window and the credit is simply gone.
The practical failure here is old invoices. A supplier sends a bill late, it sits in a folder, and by the time it is entered the window has closed. Build a habit of booking purchase invoices in the month you receive them, not the month you feel like reconciling.
The most expensive ITC is the credit you were fully entitled to but forgot to claim in time.
2. The 180 day payment rule
ITC comes with a condition that many overlook. If you do not pay your supplier within 180 days of the invoice date, the credit you already claimed has to be reversed, along with interest. Once you eventually pay, you can reclaim it.
This matters most for businesses that stretch payables. Your books may show a healthy credit position while a cluster of unpaid invoices is quietly crossing the 180 day mark. A simple ageing report on your creditors, run monthly, prevents an ugly surprise.
3. Matching with GSTR 2B
Credit is now tied to what your suppliers actually report. GSTR 2B is the static, monthly statement generated from your suppliers' filings, and it is the reference point for how much ITC you may claim. If a supplier has not filed, or has filed incorrectly, the credit will not appear, no matter how valid your invoice is.
The workflow that keeps you safe is boring and effective. Each month, compare your purchase register against GSTR 2B before you file GSTR 3B. Chase the suppliers whose invoices are missing. Do not claim credit that your 2B does not support and hope it sorts itself out.
4. Blocked credits under Section 17(5)
Some credits are blocked outright, regardless of how the expense connects to your business. The common ones that catch people include:
- Motor vehicles for personal or passenger use, with specific exceptions
- Food and beverages, outdoor catering, and club memberships
- Goods or services used for personal consumption
- Works contract services for construction of immovable property, in many cases
- Goods lost, stolen, destroyed, or given away as free samples
Claiming a blocked credit is not a grey area you can argue your way out of later. It is a straightforward reversal with interest if picked up in scrutiny. Tag these expense heads clearly in your accounting software so the credit is never claimed by default.
A quick worked example
Suppose in a month you collect GST of ₹1,80,000 on sales and your purchase register shows ₹1,20,000 of eligible ITC. Before you celebrate a net liability of ₹60,000, run the checks.
| Step | Amount | Notes |
|---|---|---|
| ITC in purchase register | ₹1,20,000 | Your books |
| Not appearing in GSTR 2B | (₹15,000) | Two suppliers filed late |
| Blocked under 17(5) | (₹6,000) | Staff catering bills |
| Eligible ITC this month | ₹99,000 | Claim this, not ₹1,20,000 |
| Net GST payable | ₹81,000 | ₹1,80,000 less ₹99,000 |
The difference between filing on the register figure and the eligible figure is ₹21,000 of credit you were not entitled to this month. Claim it and you carry a liability that resurfaces with interest. The reconciliation is what protects you.
The habit that ties it together
Every rule above points to the same monthly routine. Book purchases when they arrive, match against GSTR 2B before filing, watch your creditor ageing for the 180 day line, and tag blocked heads so they never enter the claim. None of it is difficult once it is a checklist rather than a scramble.
This article is general information and not tax advice. GST provisions change often. Confirm your position with a qualified professional before filing.