GST Return Filing Guide: GSTR-1, GSTR-3B, QRMP, IMS and Due Dates

GSTR-1 monthly

11th

Of the following month

GSTR-3B monthly

20th

QRMP: 22nd or 24th after the quarter

Late fee

₹50/day

₹20/day for nil returns, per return

Interest on late tax

18% p.a.

On net cash liability, from the due date

Who files which GST return

Every GSTIN has a filing profile decided by its scheme and turnover. Regular taxpayers with aggregate turnover above ₹5 crore file monthly. Those up to ₹5 crore can choose the Quarterly Return Monthly Payment scheme. Composition dealers file a quarterly statement and one annual return. Getting the profile right on day one avoids paying for returns you do not need.

GSTR-1: reporting your sales

GSTR-1 is the statement of outward supplies. It carries every B2B invoice with the buyer GSTIN, B2C sales in summary, exports, credit and debit notes, advances received and an HSN-wise summary. What you file here flows to your customers as their GSTR-2B, so a wrong GSTIN or a missed invoice blocks their credit and comes back as a phone call.

• B2B invoices: invoice-wise, with GSTIN, taxable value, rate and place of supply.
• B2C large: inter-state invoices above ₹1 lakh to unregistered buyers, invoice-wise.
• B2C others: consolidated by state and rate.
• Credit and debit notes: linked to the original invoice, with the reason.
• HSN summary: mandatory 6-digit codes for turnover above ₹5 crore and 4-digit below.
• GSTR-1A: an optional amendment window after GSTR-1 and before GSTR-3B, for corrections in the same period.

GSTR-3B: paying the tax

GSTR-3B is the self-assessed summary return where you declare total outward tax, claim input tax credit and pay the net amount. It cannot be revised. Any error is corrected in a later period, and if the correction increases tax, interest runs from the original due date. That single fact is the reason every filing should start with a reconciliation, not end with one.

1. Table 3.1: outward taxable supplies, zero-rated, exempt and reverse charge inward supplies.
2. Table 4: eligible ITC as per GSTR-2B, ITC reversed under rules 42 and 43, ineligible ITC under section 17(5) and reclaimed ITC.
3. Table 5: exempt and non-GST inward supplies.
4. Table 6.1: payment of tax, using ITC first and cash from the electronic cash ledger for the balance.

If your GSTR-3B liability is lower than the GSTR-1 figure by more than 20% and ₹25 lakh, the portal issues an intimation in DRC-01B under rule 88C. If ITC claimed in 3B exceeds GSTR-2B beyond the tolerance, DRC-01C under rule 88D follows. Both need a reply within 7 days or payment.

QRMP: quarterly returns with monthly payment

The QRMP scheme cuts filings from 24 to 8 a year for taxpayers with aggregate turnover up to ₹5 crore in the previous financial year. You file GSTR-1 and GSTR-3B once a quarter but must still pay tax for the first two months by the 25th of the next month through form PMT-06.

Use the IFF if your B2B customers need credit every month. Without it, a buyer who purchased from you in April sees the invoice in GSTR-2B only after your quarterly GSTR-1 in July. Larger buyers often insist on monthly IFF uploads from QRMP vendors for this reason.

IMS and GSTR-2B: how your input tax credit is decided

Section 16(2)(aa) allows ITC only on invoices that your supplier has reported in their GSTR-1 and that appear in your GSTR-2B. The Invoice Management System on the GST portal sits between the two. Every invoice, credit note and amendment uploaded by a supplier lands in your IMS dashboard, where you accept, reject or keep it pending.

1. Suppliers file GSTR-1 or IFF by the 11th or 13th. Their invoices appear in your IMS in near real time.
2. Review each record against your purchase register. Accept genuine invoices, reject ones that are not yours or are wrong, keep pending those where goods have not arrived.
3. GSTR-2B is generated on the 14th from accepted and no-action records. Pending records are excluded until you accept them. Rejected records never enter 2B.
4. If you take IMS actions after the 14th, recompute GSTR-2B from the IMS screen before filing GSTR-3B.
5. GSTR-3B Table 4 auto-fills from GSTR-2B. Claim only what is in 2B and eligible under section 16 and 17(5).

Credit claimed in 3B but missing from 2B is the single largest source of GST notices in ASMT-10 and DRC-01C. Reversal with 18% interest, or 24% where the excess credit was utilised, is the usual outcome. A monthly 2B versus books matching exercise costs far less than that.

Late fees, interest and what happens if you stop filing

Late fee under section 47 is ₹50 per day of delay for each of GSTR-1 and GSTR-3B, split equally between CGST and SGST. For a nil return it is ₹20 per day. Caps depend on turnover: ₹2,000 for turnover up to ₹1.5 crore, ₹5,000 for ₹1.5 to ₹5 crore and ₹10,000 above that, with a ₹500 cap for nil returns. Interest under section 50 is 18% per annum on the net cash tax paid late, counted from the due date to the date of payment.

• GSTR-1 for a period cannot be filed until GSTR-3B for the previous period is filed (rule 59(6)).
• E-way bill generation is blocked after two consecutive unfiled periods (rule 138E).
• Registration can be cancelled after six months of non-filing for monthly filers, or two consecutive quarters under QRMP and composition.
• A return cannot be filed at all once three years have passed from its due date, so a long-neglected GSTIN has to be regularised quickly.
• Late fee is auto-computed and must be paid before the return can be submitted.

Nil returns and amendments

A registered person with no sales and no purchases in a period must still file. Nil GSTR-1 and nil GSTR-3B can be filed through the portal in a few clicks or by SMS from the registered mobile number to 14409. Skipping a nil return costs ₹20 a day per return until it is filed.

Mistakes in GSTR-1 are corrected through the amendment tables (9A, 9B and 9C) in a later GSTR-1, or through GSTR-1A in the same period. Mistakes in GSTR-3B are corrected by adjusting the figures in a subsequent 3B. The outer time limit for amendments, for claiming missed ITC and for issuing credit notes for FY 2025-26 is 30 November 2026 or the date of filing GSTR-9, whichever is earlier.

GSTR-9 and GSTR-9C: the annual returns

GSTR-9 consolidates the year and reconciles what was filed in GSTR-1 and GSTR-3B with your books. It is optional for aggregate turnover up to ₹2 crore and mandatory above that. GSTR-9C, a reconciliation statement between audited financial statements and GSTR-9, is required above ₹5 crore and is self-certified by the taxpayer. Both are due by 31 December of the following year, so FY 2025-26 returns are due by 31 December 2026.

The annual return is also the last chance to pay any shortfall found during the year through DRC-03 with interest, before the department finds it in scrutiny. Composition dealers file GSTR-4 by 30 June instead.

A monthly filing checklist

1. By the 5th: close the sales register, check e-invoices where applicable (mandatory above ₹5 crore turnover), and prepare the HSN summary.
2. By the 10th: file GSTR-1 or IFF. Confirm customer GSTINs are active.
3. By the 13th: take IMS actions on supplier invoices.
4. On the 14th: download GSTR-2B and match it with the purchase register.
5. By the 18th: compute net liability, create the challan, and pay through the cash ledger.
6. By the 20th (or QRMP dates): file GSTR-3B and save the acknowledgement.
7. Monthly: update the vendor follow-up list for invoices missing from 2B.

What to do next

Check your filing profile on the portal, note whether you are monthly or QRMP, and put the dates above into a calendar with reminders three days ahead. If reconciling IMS and GSTR-2B every month is eating your time, or you have a backlog of unfiled periods, an expert-assisted filing plan handles the matching and files before the due date, with a draft shared for your approval.