We forgot an invoice in GSTR-1 and our buyer cannot see it. What now?

Your customer rings. They have your tax invoice, they have paid you, but it is not showing in their GST portal. Their accountant says they cannot claim the input tax credit (ITC) on it. You check and find the reason: the invoice never went into your GSTR-1.

This article is for a company that sells to GST-registered buyers and has found that one or more invoices were left out of GSTR-1. It covers why the buyer's credit is stuck, what the CGST Act lets you do, the cut-off after which you cannot fix it, and the order of steps. If the invoice went in but with the wrong GSTIN, that is a different problem and not covered here.

Why the buyer's credit is stuck

A buyer can take ITC only if the law's conditions are met. One of them is in section 16(2)(aa) of the CGST Act, 2017. It says no registered person is entitled to the credit of any input tax on a supply to him unless "the details of the invoice or debit note referred to in clause (a) has been furnished by the supplier in the statement of outward supplies and such details have been communicated to the recipient of such invoice or debit note in the manner specified under section 37".

In plain words: the credit follows what the seller reports. Section 37(1) requires every registered person (with listed exceptions such as an Input Service Distributor, a non-resident taxable person and a person paying tax under section 10, 51 or 52) to furnish the details of outward supplies for a tax period, and says those details "shall, subject to such conditions and restrictions, within such time and in such manner as may be prescribed, be communicated to the recipient of the said supplies". If the invoice was never furnished, there is nothing to communicate, and the buyer's side stays empty.

So the fault sits with you, and only you can fix it. The buyer cannot make the credit appear by any step of their own.

What you can still do today

The Act gives two connected routes, and the rules add a third for a narrow window.

1. Rectify the omission (section 37(3) and section 39(9), CGST Act, 2017).

Section 37(3) says a registered person who has furnished the details under section 37(1) for a tax period shall, "upon discovery of any error or omission therein, rectify such error or omission in such manner as may be prescribed, and shall pay the tax and interest, if any, in case there is a short payment of tax on account of such error or omission, in the return to be furnished for such tax period".

Section 39(9) says the same thing from the return side. Where a registered person, after furnishing a return, "discovers any omission or incorrect particulars therein, other than as a result of scrutiny, audit, inspection or enforcement activity by the tax authorities, he shall rectify such omission or incorrect particulars in such form and manner as may be prescribed, subject to payment of interest under this Act".

An invoice left out of GSTR-1 is exactly an "omission". Note the exclusion: section 39(9) applies where you found the omission yourself, not where it came out through scrutiny, audit, inspection or enforcement activity by the tax authorities.

2. GSTR-1A, if GSTR-3B for that month is still not filed (rule 59(1), proviso, CGST Rules, 2017).

Rule 59(1) of the CGST Rules, 2017, as amended by Notification No. 12/2024-Central Tax, lets a person, "after furnishing the details of outward supplies of goods or service or both in FORM GSTR-1 for a tax period but before filing of return in FORM GSTR-3B for the said tax period, at his own option, amend or furnish additional details of outward supplies" in FORM GSTR-1A for that period.

"Furnish additional details" is the useful phrase: it covers adding an invoice you left out. The window closes when you file GSTR-3B for that same tax period. Check on the GST portal whether the GSTR-1A facility is open for your period before you rely on it.

3. Invoice furnishing facility (IFF), for quarterly filers (rule 59(2)).

A registered person who files quarterly under the proviso to section 39(1) can furnish invoices to registered buyers for the first and second months of a quarter using the IFF, up to a cumulative value of fifty lakh rupees in each of those months. Rule 59(2) allows this from the 1st day of the following month till the 13th day of that month. If you are a quarterly filer and the omitted invoice falls in month one or two, this can get it to the buyer without waiting for the quarter-end GSTR-1, but only inside that 1st-to-13th window; once it has passed, the invoice belongs in the quarterly GSTR-1.

Once GSTR-3B for the month is also filed, the Act leaves the form and manner of rectification to the rules ("in such manner as may be prescribed"). The screen-by-screen portal steps for that stage are not set out in the sections discussed here, so confirm on the portal how it accepts the invoice for your period, and have your CA do it if it is not obvious.

The deadline clock

Two cut-offs matter, one for you and one for the buyer.

Your cut-off. The proviso to section 37(3) says no rectification of error or omission in the details furnished under section 37(1) "shall be allowed after the thirtieth day of November following the end of the financial year to which such details pertain, or furnishing of the relevant annual return, whichever is earlier". Section 39(9) carries the same proviso for rectification of returns ("or the actual date of furnishing of relevant annual return, whichever is earlier"). For an invoice dated in FY 2025-26, that year ends on 31 March 2026, so the thirtieth day of November following is 30 November 2026, or the furnishing of the relevant annual return, whichever comes first. If the annual return for that year has already been filed, the window may be closed.

The buyer's cut-off. Section 16(4) says a registered person shall not be entitled to take ITC on an invoice or debit note "after the thirtieth day of November following the end of financial year" to which it pertains, "or furnishing of the relevant annual return, whichever is earlier". So even if you fix it, the buyer must claim in time.

The three-year bar. Section 37(5) says a registered person shall not be allowed to furnish the details of outward supplies under section 37(1) for a tax period after the expiry of three years from the due date of furnishing those details, and section 39(11) says the same for a return. Each has a proviso allowing the Government, on the Council's recommendation, to notify otherwise. This matters for very old omissions.

Interest and tax: do you owe anything?

Section 37(3) asks you to pay the tax and interest "in case there is a short payment of tax on account of such error or omission". That wording splits the situation in two.

• You paid the tax on that invoice through GSTR-3B and only left it out of GSTR-1. Then there may be no short payment at all. The error is a reporting gap, not a payment gap. Tie your GSTR-3B output tax to your sales register for the month to confirm.
• You left it out of both GSTR-1 and GSTR-3B. Then tax is short. Section 50(1) makes a person who fails to pay tax within the prescribed period pay interest "on his own" at a rate not exceeding eighteen per cent., as notified, for the period the tax remains unpaid. The rate actually applicable is notified separately; check the current rate with your CA or on the portal before you compute it.

Section 50(1) has a proviso that matters if the return was filed late: for tax on supplies made in a tax period and declared in a return furnished after the due date, interest is levied on that portion of the tax that is paid by debiting the electronic cash ledger (the proviso excepts a return furnished after proceedings under section 73, 74 or 74A have begun).

A late fee under the Act for delayed filing is a separate matter. No amount is stated here; check the current figure on the portal or with your CA.

Step by step

• List what is missing. Pull your sales register and compare it, invoice by invoice, to what you reported in GSTR-1. Note the invoice number, date, buyer GSTIN, taxable value and tax.
• Check that the tax was paid. For each missing invoice, see whether the tax went into the GSTR-3B for that month. If it did, you owe no extra tax; if it did not, you do.
• Find which window you are in. If GSTR-3B for that period is not yet filed, GSTR-1A is the route (rule 59(1), proviso). If it is filed, the Act leaves the manner to the rules; ask your CA how the portal accepts the invoice for that period, and note the section 37(3) cut-off. For a quarterly filer and a month one or two invoice, look at the IFF (rule 59(2)).
• Mind the blocks on filing. Rule 59(6)(a) says a registered person shall not be allowed to furnish outward supply details in GSTR-1 if the GSTR-3B for the preceding month has not been furnished. A quarterly filer is blocked in the same way if GSTR-3B for the preceding tax period is pending (rule 59(6)(b)). If you have received an intimation under rule 88C or 88D, rule 59(6)(d) and (e) also block GSTR-1 until you pay the amount stated or reply with reasons. And rule 59(6)(f) blocks it if you have not furnished your bank account details under rule 10A. Clear whichever applies first.
• Report the invoice. Enter it with the correct buyer GSTIN, invoice number, date and tax. File.
• Pay any tax and interest that are due, as section 37(3) and section 50(1) require.
• Tell the buyer. Send them the invoice number and the date you reported it, and remind them of their own cut-off under section 16(4).

What not to do

• Do not raise a second invoice for the same supply. The sale is already invoiced; a duplicate creates a double liability and a double credit claim.
• Do not tell the buyer to "claim it anyway". Section 16(2)(aa) ties their credit to your reporting. A credit taken without it is not allowed, and the buyer also has the 180-day payment rule in the second proviso to section 16(2): if they do not pay you the value plus tax within one hundred and eighty days from the invoice date, they must pay back the credit with interest.
• Do not let the date pass. After the 30 November cut-off the Act does not allow the rectification, and the buyer's right to take the credit ends at the section 16(4) cut-off.

What to do now

• Next step: match your sales register to GSTR-1 for every month of the current financial year and list each missing invoice (section 37(3), CGST Act, 2017).
• Deadline: for FY 2025-26 invoices, 30 November 2026 or the furnishing of the relevant annual return, whichever is earlier, for you to rectify (proviso to section 37(3) and proviso to section 39(9)), and the same two limbs for the buyer to take the credit (section 16(4)).
• Consequence of missing it: the correction is not allowed after the cut-off, and the buyer loses the credit on that invoice, which can lead to a commercial dispute with a customer. If tax was left unpaid, interest runs under section 50(1).

Have a CA review your facts before you act or file.

FAQs

1. The buyer has already paid us. Does the missing invoice change anything on payment?
No. Payment and reporting are separate. The buyer's payment does not create the credit; section 16(2)(aa) requires your reporting. They should still pay within one hundred and eighty days from the invoice date to avoid a reversal under the second proviso to section 16(2).

2. Can we just include the old invoice in this month's GSTR-1?
Section 37(3) ties the correction to the tax period it relates to and to the cut-off. Whether the portal lets you enter an old invoice in the current month's GSTR-1, and against which tax period it records it, is portal practice that the Act and Rules do not spell out in the provisions discussed here. Treat it as unconfirmed and check with your CA before relying on it.

3. We found the omission after a notice. Does section 39(9) still help?
Section 39(9) excludes omissions discovered "as a result of scrutiny, audit, inspection or enforcement activity by the tax authorities". If the notice led you to it, reply to the notice and take advice; do not assume the self-correction route applies.

4. Is there a penalty for leaving out an invoice?
The provisions discussed here deal with rectification, interest on tax that was short paid, and late fee. This article does not cover penalty for this omission; ask your CA if a notice is raised.

5. Our annual return is already filed. Is it too late?
The proviso to section 37(3) cuts off rectification at the earlier of 30 November following the financial year or furnishing of the relevant annual return. If the annual return is in, the window may be shut for that year. Speak to your CA about the options for the buyer.

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See Also

• What is the last date to claim ITC on my purchase invoices for the year?
• Where do I report reverse charge (RCM) in GSTR-3B?
• I filed GSTR-1 with the wrong GSTIN — can the invoice still be fixed?