Something Wrong With Last Year's Invoices? You Have Until 30 November. Maybe Less.

Most freelancers think of March as the end of the GST year. It isn't. For anything that went wrong between April 2025 and March 2026, the law gives you until 30 November 2026 to fix it. After that, three doors close at once:

• A credit note on a 2025-26 invoice can no longer reduce the GST you paid.
• GST you paid on your own purchases in 2025-26 (laptop, coworking, software) can no longer be claimed back.
• Mistakes in 2025-26 invoices you reported in GSTR-1 can no longer be amended.

And if you file quarterly, which most solo freelancers do, your practical deadline is not 30 November. It's around 22 October. That's about five weeks from today.

Not tax advice. This explains a deadline and the decisions around it so you can go to your CA with the right questions. Dates below are for FY 2025-26 (April 2025 to March 2026). Verify your own filing frequency and state before acting.

Why 30 November, and why it might be earlier for you

Three sections of the CGST Act use the same cut-off: Section 16(4) for claiming input tax credit (ITC), Section 34(2) for credit notes, and Section 37(3) for correcting GSTR-1. Each says the same thing: the earlier of 30 November after the financial year ends, or the date you file that year's annual return (GSTR-9).

The date only counts if the fix is in a return you actually file by then. Which return that is depends on how often you file:

Quarterly filers' next GSTR-3B covers October to December and can't be filed until January. That's after 30 November. So the July–September quarter return is your last chance. The 22nd applies to states like Gujarat, Maharashtra, Karnataka and Tamil Nadu; the 24th to states like Delhi, Uttar Pradesh and West Bengal.

If you don't know which one you are, check your GST portal dashboard or ask your CA. It changes the deadline by a month.

The GSTR-9 trap

Most freelancers are well under ₹2 crore turnover, where GSTR-9 has been optional in recent years. Some CAs file it anyway, early, to tidy up.

If your GSTR-9 for FY 2025-26 is filed in, say, September, then September becomes your deadline for everything above. Anything you haven't fixed by then stays unfixed.

If your CA plans to file it, ask them to wait until you've gone through the three checks below.

Check 1: Invoices that should be smaller now

The common freelancer version isn't a returned product. It's one of these:

• You invoiced ₹1,50,000 + GST in February, the client cut scope, you agreed on ₹1,00,000.
• You gave a discount after the invoice went out.
• A project was cancelled after you'd already invoiced and paid the GST.

In each case you paid GST on money you'll never receive. A credit note gets it back, by reducing your output tax in the month you report it. For a 2025-26 invoice, it must be reported by the deadline above.

After that, you can still issue a credit note as a commercial document, but it carries no GST effect. The extra tax you paid stays paid.

What changed in October 2025: if your client is GST-registered, your tax reduction now depends on them reversing the matching input tax credit on their side. That happens through the Invoice Management System (IMS) on the portal, where they accept your credit note. If they ignore it, your reduction doesn't go through.

So don't issue the credit note on 20 November and hope. Issue it now, tell your client's accounts person it's coming, and check it's been accepted.

Export invoices under LUT: you charged no IGST, so there's no tax to recover. You should still issue the credit note so your GSTR-1 export value matches what actually landed in your bank. This matters later if the difference ever comes up, including under the one-year clock on unpaid export invoices.

Advances for cancelled work: if you took an advance in 2025-26, paid GST on it, and the project was cancelled, the fix is a refund voucher, not a credit note. See GST on advance payments for how that works, and treat the same deadline as applying.

Check 2: GST you paid and never claimed back

Freelancers often don't claim ITC because the amounts feel small. They add up. Look through 2025-26 for:

• Equipment — laptop, monitor, phone used for work.
• Coworking, internet, CA fees from GST-registered vendors.
• Software paid in rupees to Indian sellers.
• Foreign software under reverse charge — Figma, Vercel, GitHub, AWS paid in dollars.

For the first three, you can only claim ITC if the invoice shows your GSTIN and the vendor reported it. Check your GSTR-2B for each month. A laptop bought on a personal account with no GSTIN on the bill doesn't qualify, however clearly it's used for work.

For foreign software, the rule is different. You pay the IGST yourself under reverse charge and issue a self-invoice, and the ITC is claimed against that. The financial year that counts for the deadline is the year of your self-invoice, not the date you paid the subscription. If you've been skipping this entirely, read self-invoicing under reverse charge for Figma and Vercel first. Catching up is possible, but interest applies and the ITC timing needs your CA.

If most of your work is exports under LUT: you charge no GST on exports, so ITC tends to pile up unused in your credit ledger. That pile is what you can later claim as a refund. ITC you never claimed isn't in the pile, so it can't be refunded either.

One reversal to check: if a vendor you claimed ITC from in 2025-26 didn't file their own GSTR-3B for that period by 30 September 2026, you're expected to reverse that ITC by 30 November. You can re-claim it once they file. Your CA can spot this from the portal in a few minutes.

Check 3: Invoices you reported wrongly

Go through your 2025-26 GSTR-1 against your invoices. The usual errors:

• Wrong client GSTIN, or a B2B invoice reported as B2C. Your client can't claim ITC until this is fixed, and they'll eventually notice. If you're unsure which particulars had to be on the invoice in the first place, what a valid GST tax invoice must include is the checklist.
• Wrong amount that you never corrected.
• An invoice you never reported at all.

The first two are amendments, and amendments for a 2025-26 invoice close with the same deadline. After that, your client's ITC problem becomes permanent, which is not a conversation you want in January. The mechanics are in what you can still change on an invoice you already sent.

A missing invoice is different. Adding tax you owe is never time-barred. You report it, pay it with interest, and move on. But if the client is GST-registered, their ITC on it still dies on 30 November, so report it before then.

CGST+SGST charged where it should have been IGST (or the reverse): this isn't fixed by amending. You pay under the correct head and claim a refund of the wrong one. Talk to your CA before touching it.

The 20-minute version

If you do nothing else this week:

1. 1.Find out if you file monthly or quarterly. That sets your real deadline.
2. 2.List every 2025-26 invoice where the amount you were finally paid differs from the invoice. Each one needs a credit note or an explanation.
3. 3.Download your GSTR-2B for April 2025 to March 2026 and compare it with the purchase bills you have. Anything with your GSTIN on it that you didn't claim is money on the table.
4. 4.List every foreign subscription you paid in 2025-26. Check each has a self-invoice.
5. 5.Tell your CA not to file GSTR-9 for 2025-26 until you've done the above.

Next year, make this a 5-minute job

The reason November is stressful is that the gap between what you billed and what you were actually paid only becomes visible when someone goes looking for it.

Mavoin keeps every invoice, its amount and its payment status in one list, so that gap is visible every month instead of discovered in November. ₹199/month after the trial, and your data stays exportable.

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Sources: Section 16, CGST Act 2017 (CBIC) · Section 34, CGST Act 2017 (CBIC) · Section 37, CGST Act 2017 (CBIC)

Mavoin is not a Chartered Accountant service. General information, current as of September 2026. Verify GST specifics with your CA.