Input Tax Credit (ITC) Basics for Small Businesses

In one line: when your business pays GST on something it buys for business use, input tax credit (ITC) lets you subtract that already-paid GST from what you owe the government on your own sales — so you only ever pay GST on the value your business actually adds, not on the full price all over again.

Why does ITC exist?

GST is designed as a value-added tax collected at every stage of a supply chain. Without a credit mechanism, tax would stack on tax as goods and services move from supplier to supplier before reaching the final customer. ITC is what prevents that: each registered business in the chain pays GST on its purchases, then claims that amount back against the GST it collects on its own sales, so the net amount remitted to the government at each stage reflects only that business's own value addition.

What do I actually need to claim a credit?

To claim ITC on a purchase, you generally need all of the following to be true:

• You hold a valid tax invoice (or debit note) from the supplier — see our GST invoice format checklist for what makes an invoice valid in the first place.
• The goods or services described on that invoice were actually received by your business.
• Your supplier has actually reported and paid that tax to the government — this shows up on your GSTR-2B statement, which is why a genuine invoice from a supplier who hasn't filed correctly can still cause your credit to be blocked.
• You've filed your own relevant GST return for the period.
• You pay your supplier within 180 days of the invoice date (see below for what happens if you don't).

What happens if I pay my supplier late?

If payment to the supplier isn't made within 180 days of the invoice date, the ITC you claimed on that purchase must be reversed — added back to your output tax liability, with interest, until you actually pay. Once you do pay, you're allowed to re-claim the credit. This rule catches businesses that claim ITC promptly on receipt of an invoice but are slow to settle payment, so it's worth tracking supplier payment dates alongside invoice dates, not just invoice dates alone.

What can't I claim ITC on?

Certain categories are blocked or restricted by law regardless of whether they're genuinely used for business — getting this wrong is one of the more common ITC mistakes. A non-exhaustive illustrative list:

This list is illustrative, not exhaustive — the full blocked-credit list lives in Section 17 of the CGST Act and related rules, and has specific carve-outs and edge cases that matter in practice. Confirm anything unusual with a tax professional or the CBIC directly before relying on a summary like this one.

Worked example

A small business collects ₹18,000 of GST on its sales in a month. During the same month it made eligible business purchases with ₹5,000 of GST already paid on them (and met all the conditions above). Net GST payable to the government for the month is ₹18,000 − ₹5,000 = ₹13,000, not the full ₹18,000.

What if I make both taxable and exempt supplies?

Businesses that supply a mix of taxable and GST-exempt goods or services generally can't claim full ITC on purchases used for both — a proportionate reversal formula applies to the portion of input tax attributable to exempt supplies. This is a genuinely more involved calculation than the basics above and is worth handling with a tax professional if it applies to you, rather than estimating it yourself.

ITC you pay under reverse charge follows the same eligibility rules described here — see our reverse charge mechanism guide for when that applies in the first place.