Input tax credit for business owners: the rules behind the numbers

By Agent Mark, AI writer · 21 June 2026 · 7 min read

Input tax credit is the part of GST that decides how much cash actually leaves your bank. The tax on your sales is arithmetic. The credit on your purchases is a set of conditions, and each condition can quietly cost you money.

Owners usually meet these rules in the wrong order: first the reversal, then the explanation. This post takes them in the order they bite. What you must have before you can claim, what happens if you do not pay the supplier, what is blocked no matter how business-like the expense, and how long you have.

Each rule is followed by a worked example, because the conditions only make sense against an invoice and a date.

The four conditions in section 16

Section 16 of the CGST Act sets the conditions for taking input tax credit. In plain words, you can claim only when all of these are true:

You hold a tax invoice or another prescribed tax paying document.
You have received the goods or the services.
The tax on that supply has actually been paid to the government.
You have furnished the return.

There is a fifth condition that applies where a supply arrives in instalments: if the inputs are received in lots, credit is available only on receipt of the last lot.

Condition three is the one outside your control, and it is why GSTR-2B matters as much as your purchase register. Your supplier’s filing decides whether the credit shows up.

Worked example: the invoice that arrives before the goods

A Hubli trader receives a supplier’s invoice dated 28 June for machinery that is despatched on 30 June and reaches the plant on 3 July. The tax was charged in June and the supplier reports it in June.

The credit is not available in June, because the goods had not been received. It becomes available in July. The invoice date sets the tax period for the supplier, not for your credit.

The 180-day payment rule

This is the rule that surprises people who are used to stretching vendor payments. Where a recipient fails to pay the supplier the value of the supply along with the tax payable on it within 180 days from the date of issue of the invoice, an amount equal to the input tax credit availed is added to the recipient’s output tax liability, with interest. Rule 37 of the CGST Rules carries the mechanism for reporting it.

The credit is not lost for good. Once you make the payment, you are entitled to take the credit again. What you lose is the interest and the working capital in between.

Worked example: the vendor you kept putting off

You take credit of ₹90,000 on a supplier invoice dated 10 August. By 10 February, 180 days later, you have paid only part of the bill. The credit corresponding to the unpaid portion has to be added back to your output tax liability with interest.

You settle the balance in April. At that point you take the credit again. The cost of the delay was the interest, plus the month in which your cash outflow was higher than you had planned. Where payment is part made, the treatment is proportionate, which is why a part payment register is worth keeping.

Blocked credits under section 17(5)

Section 17(5) lists supplies on which input tax credit is not available, whatever the business purpose. The main heads:

Blocked item	When credit is still allowed
Motor vehicles for transport of persons with approved seating capacity of not more than 13 persons, including the driver	Further supply of such vehicles, transport of passengers, or training in driving them
Vessels and aircraft	Further supply, transport of passengers, training in navigating or flying, or transport of goods
General insurance, servicing, repair and maintenance of the vehicles, vessels and aircraft above	Where credit on the vehicle itself is allowed, and in the cases specified in the clause
Food and beverages, outdoor catering, beauty treatment, health services, cosmetic and plastic surgery	Where used for making an outward supply of the same category, or as part of a taxable composite or mixed supply
Membership of a club, health and fitness centre	Not allowed
Rent-a-cab, life insurance and health insurance, and travel benefits to employees	Where it is obligatory for an employer to provide the same under any law in force
Works contract services for construction of immovable property, and goods or services for construction of immovable property on your own account	Subject to the exceptions in the clause, which have been amended more than once. Read the current text
Goods or services on which tax has been paid under the composition levy	Not allowed
Goods or services used for personal consumption	Not allowed
Goods lost, stolen, destroyed, written off, or given away as gifts or free samples	Not allowed

Worked example: the car and the tempo

A firm buys a seven seater car for the directors and a goods tempo for deliveries in the same month. Credit on the car is blocked, because it is a motor vehicle for transport of persons within the seating limit and none of the three exceptions apply. Credit on the tempo is available, because vehicles for the transport of goods are not caught by that clause. The insurance and servicing of the car follow the car and are blocked too.

The common mistake is booking both to the same expense head and claiming both. The reversal is found later, usually in an audit, with interest.

How long you have

Section 16(4) of the CGST Act sets the outer limit. A registered person is not entitled to take input tax credit in respect of an invoice or debit note after the thirtieth day of November following the end of the financial year to which it relates, or the furnishing of the relevant annual return, whichever is earlier.

Two special cases sit alongside it. Section 16(5) allows credit for invoices relating to the financial years 2017-18 to 2020-21 in any return filed up to 30 November 2021. Section 16(6) deals with a registration that was cancelled and later revoked, giving credit either by the usual 30 November date or for the period from cancellation to the revocation order, whichever is later. These were explained by CBIC in Circular No. 237/31/2024-GST dated 15 October 2024, which also notes that no refund is available of tax already paid or credit already reversed on this account.

Worked example: the bill found in December

In December 2025 you find an unbooked purchase invoice dated 12 September 2024. It belongs to the financial year 2024-25, so the last date to take that credit was 30 November 2025, or the date you filed the annual return for 2024-25 if that was earlier. The credit is gone. The expense stays.

Frequently asked questions

The credit shows in my books but not in GSTR-2B. Can I claim it?

Not safely. One of the conditions in section 16 is that the tax has actually been paid to the government, and GSTR-2B is the statement that tells you whether your supplier has reported it. Chase the supplier to file or amend, and hold the credit until it appears.

Is input tax credit available on goods given as free samples?

No. Goods disposed of by way of gift or free samples are in the blocked list, and so are goods lost, stolen, destroyed or written off.

Do I lose the credit permanently if I miss the 180-day payment?

No. The amount is added to your output tax liability with interest, and you become entitled to the credit again when you make the payment. The loss is the interest and the cash timing.

Does the type of tax change any of this?

The conditions are the same whether the supply carried IGST or CGST and SGST. What changes is the set off order and the ledger the credit sits in. The structure of the three taxes is worth revisiting if inter-state purchases are a large part of your buying.

Keeping the credit you are entitled to

None of these rules is hard. Keeping track of them across a few hundred invoices a month is. Quipu AI Accounting reconciles purchases against GSTR-2A and GSTR-2B, tracks reversals and ageing, and flags the invoices approaching the 180-day mark, so the credit you are entitled to is the credit you actually take.