GST does not end on 31 March. The financial year closes then, but the law leaves several corrections open until 30 November and the annual return until 31 December. A business that works through the year end in three stages, before March, by November and by December, rarely loses credit or pays a fee it could have avoided.
The dates below are for the 2025-26 and 2026-27 years, as of October 2026.
01Before 31 March: set up the new year
| Task | Why | By |
|---|---|---|
| File a Letter of Undertaking for the next year (RFD-11) | Exports and SEZ supplies from 1 April without IGST | Before the first export of April |
| Opt into the composition scheme for the next year (CMP-02), if you qualify and want to | The option must be filed before the year starts | 31 March |
| Decide monthly or quarterly filing for April to June | The QRMP window for that quarter runs 1 February to 30 April | 30 April |
| Start new invoice, credit note and challan series | Numbers must be unique for the financial year | 1 April |
| Check last year's aggregate turnover against the lines that matter | It decides HSN digits, e-invoicing, QRMP eligibility and late fee caps | Early April |
The turnover lines to check
| If last year's aggregate turnover crossed | What changes |
|---|---|
| ₹1.5 crore | Composition is no longer open, and late fee caps go up |
| ₹5 crore | 6-digit HSN on all invoices, QRMP no longer open, e-invoicing from now on, GSTR-9C applies |
| ₹10 crore | Invoices must be reported to the IRP within 30 days |
02Through April and May: close the books
- Count stock and agree it with the books. Goods lost, stolen or destroyed need their credit reversed.
- Match sales. Books against GSTR-1, and GSTR-1 against GSTR-3B, month by month.
- Match purchases. Purchase register against GSTR-2B for the whole year. List the bills still missing.
- Check reverse charge. Every director fee, advocate fee, GTA bill and unregistered rent should have tax paid under reverse charge.
- Review unpaid supplier bills. Credit on bills unpaid for more than 180 days must be reversed until paid.
- Work out the annual reversal for common credit if you make both taxable and exempt supplies, under rules 42 and 43.
- File ITC-04 for job work: by 25 April for the second half-year if your turnover is above ₹5 crore, or the annual return by 25 April otherwise.
03By 30 November: the last corrections
30 November is the most important date in the GST year after the monthly returns. For supplies and purchases of 2025-26, it is the last date to:
| Task | Section |
|---|---|
| Claim input tax credit on any invoice or debit note of 2025-26 | Section 16(4) |
| Issue and declare credit notes for supplies of 2025-26 | Section 34 |
| Correct errors in details of 2025-26 supplies reported in GSTR-1 | Section 37 |
| Reverse credit on invoices whose suppliers did not file GSTR-3B by 30 September | Rule 37A |
If you file the annual return before 30 November, the earlier date applies for credit and credit notes.
A Morbi tile maker that finds, in October 2026, a March 2026 bill for packing material that was never claimed can still claim it in the GSTR-3B for October, filed by 20 November. If the same bill is found in December, the credit is gone.
04By 31 December: the annual return
| Return | Who | Due |
|---|---|---|
| GSTR-9 | Regular taxpayers, except those exempted by notification for the year | 31 December |
| GSTR-9C | Taxpayers with aggregate turnover above ₹5 crore | With GSTR-9, by 31 December |
| GSTR-4 | Composition dealers | 30 June, for the year ended 31 March |
For recent years, taxpayers with turnover up to ₹2 crore have been exempted from GSTR-9 by notification. Check the notification for the year you are filing.
GSTR-9 summarises the year: sales, credit, tax paid, and the corrections made after the year in the April to November returns. It does not let you claim new credit or pay new tax by itself. Any tax found short while preparing it is paid separately through DRC-03.
05A worked timeline
A Rajkot pump maker with ₹7 crore turnover in 2025-26 works through the year end like this:
| When | What |
|---|---|
| March 2026 | Filed LUT for 2026-27, started INV/26-27 series |
| April 2026 | Counted stock, filed ITC-04 for October to March by 25 April |
| May to August 2026 | Matched books to GSTR-1, GSTR-3B and GSTR-2B for every month of 2025-26 |
| September 2026 | Wrote to suppliers with missing bills, issued pending credit notes to dealers |
| October 2026 | Claimed the last confirmed credit for 2025-26 in October's GSTR-3B |
| December 2026 | Filed GSTR-9 and GSTR-9C by 31 December |
06What larger and smaller firms do differently
A shop with ₹60 lakh turnover under QRMP may need only a day for the year end: count stock, check the four quarterly returns against the books, and start a new bill series. A company with several GSTINs needs the full routine for each GSTIN, because returns, credit and annual returns are all by GSTIN.
07Common year-end mistakes
- Waiting for GSTR-9 to fix errors. Most corrections must be made by 30 November, in the monthly or quarterly returns.
- Filing GSTR-9 early and so losing the time until 30 November for credit and credit notes.
- Forgetting the LUT and charging IGST on April exports by mistake.
- Carrying the old invoice series into the new year.
This guide is general information as of October 2026 and does not amount to tax advice.
MatruOS keeps a GST summary for each month and builds the GSTR-1 file from your invoices, which shortens the matching work at year end.