How to file GST returns in 2026: the monthly sequence, step by step

Composition dealers file CMP-08 by the 18th of the month after each quarter and GSTR-4 annually by 30 June. Businesses with turnover above ₹5 crore also generate an e-invoice for every B2B supply before it is issued, and those above ₹10 crore must report it to the portal within 30 days of the invoice date.

GSTR-1 is the source of everything downstream: your customers’ credit, and your own GSTR-3B liability. Before filing, match the sales register to the e-invoices generated, check that every B2B invoice carries the customer’s correct GSTIN, and classify credit notes and amendments against the original invoices. HSN summary is mandatory at four or six digits depending on turnover, and the portal validates it.

File by the 11th. Once filed, the invoices appear in each customer’s GSTR-2B and your liability flows into your own GSTR-3B. A GSTR-1 filed late delays your customers’ credit, which is the fastest way to lose a B2B customer.

Every invoice your suppliers report against your GSTIN lands in the Invoice Management System, where you accept, reject or keep it pending. Accepted invoices flow into GSTR-2B, which the portal generates on the 14th; rejected ones do not, and pending ones wait. Doing nothing is treated as acceptance.

This is the step that decides your input tax credit. Reject an invoice you never received, keep pending one whose goods have not arrived, and chase suppliers who have not filed at all — credit on an invoice missing from GSTR-2B cannot be claimed, however genuine the purchase. Reconcile the purchase register against GSTR-2B every month; the year-end reconciliation in GSTR-9 is where unresolved differences become tax demands.

From the July 2025 tax period, the outward liability auto-populated into GSTR-3B from GSTR-1 and the IFF is locked. If an invoice was reported wrongly, the correction is made in GSTR-1A for the same period, before GSTR-3B is filed, so that the corrected figure flows through. Once GSTR-3B is filed, the fix moves to next month’s GSTR-1 as an amendment.

The department has indicated that the credit side, Table 4 of GSTR-3B, is the next to be locked to GSTR-2B and the IMS actions. Treat it as locked already: claim what GSTR-2B supports, and reverse what it does not.

With liability and credit in place, GSTR-3B is a review: confirm the auto-populated liability, claim eligible credit, reverse ineligible or blocked credit under section 17, pay the net through the electronic cash ledger, and file by the 20th. Companies and LLPs sign with a digital signature; others may use an electronic verification code.

QRMP taxpayers pay months one and two through PMT-06 by the 25th of the following month, either 35 percent of the previous quarter’s cash tax or the actual amount, and settle in the quarterly GSTR-3B. Nil returns can be filed by SMS.

Late fee. ₹50 a day for GSTR-1 and GSTR-3B (₹25 each under CGST and SGST), and ₹20 a day for a nil return. The fee is capped per return by turnover: ₹500 for nil returns, ₹2,000 where turnover is up to ₹1.5 crore, ₹5,000 up to ₹5 crore, and ₹10,000 above that.

Interest. 18 percent a year on the net cash liability paid late, from the due date to the date of payment. Interest on wrongly availed and utilised credit runs at the same rate.

Blocked filing. GSTR-1 cannot be filed if the previous GSTR-3B is pending, and e-way bills are blocked after two consecutive unfiled GSTR-3Bs. Registration can be suspended and then cancelled for six months of non-filing.

The three-year bar. Since 1 August 2025 the portal does not accept any return more than three years after its due date. A return that was never filed for a period before then is now permanently unfilable, and the liability for it is recovered by assessment instead. Our late fee calculator works out the fee and interest for a given delay.

1. By the 7th: sales register matched to e-invoices, credit notes classified, HSN summary ready.
2. By the 11th: GSTR-1 filed (or IFF for QRMP).
3. By the 13th: IMS actions taken on every supplier invoice for the period.
4. 14th: GSTR-2B generated; reconcile it to the purchase register, chase non-filing suppliers.
5. By the 18th: GSTR-1A corrections if any; GSTR-3B reviewed, cash ledger funded.
6. By the 20th: GSTR-3B filed, challan retained.
7. Quarterly: review blocked credit, reverse credit on unpaid supplier invoices older than 180 days, refresh the LUT each April.

Returns are filed on the GST portal. Our return filing service runs this sequence for you every month from ₹499, with the reconciliation done before the due date rather than at year end.