GSTR-1 and GSTR-3B filing guide: tables, due dates, QRMP and a monthly routine

Every regular GST taxpayer files two returns: GSTR-1, the invoice-wise statement of sales, and GSTR-3B, the summary where you claim input tax credit and pay tax. Monthly filers submit GSTR-1 by the 11th and GSTR-3B by the 20th of the next month. Businesses with turnover up to ₹5 crore can opt for QRMP and file both quarterly while paying tax monthly through PMT-06 by the 25th. Nil returns are still mandatory, and late fees start the day after the due date.

Monthly versus QRMP: which one applies to you

Under Section 39 and Rule 61A, a registered person with aggregate turnover up to ₹5 crore in the previous financial year can choose the Quarterly Return Monthly Payment (QRMP) scheme. Everyone else files monthly. The choice is made on the portal and can be changed once a quarter; the option for a quarter must be exercised before the quarter starts (the window opens on the first day of the second month of the previous quarter and closes on the last day of the first month of the quarter).

GSTR-3B under QRMP is due on the 22nd for taxpayers in Chhattisgarh, Madhya Pradesh, Gujarat, Maharashtra, Karnataka, Goa, Kerala, Tamil Nadu, Telangana, Andhra Pradesh, Daman and Diu, Dadra and Nagar Haveli, Puducherry, Andaman and Nicobar, and Lakshadweep, and on the 24th for the rest of India. Confirm the date for your state on the GST due dates calendar.

QRMP halves the number of returns but not the number of payments. If most of your customers are registered businesses, the IFF becomes essential, otherwise they wait up to three months for credit and may prefer a monthly-filing supplier.

What goes in each table of GSTR-1

GSTR-1 (Section 37, Rule 59) is filed from your sales register. The tables a small business actually uses:

The B2C large-invoice threshold in Table 5 was reduced from ₹2.5 lakh to ₹1 lakh in 2024. Table 12 became mandatory with HSN selection from a dropdown and a B2B/B2C split in 2025; see our HSN and SAC guide for the digit requirements. Table 13 is where your invoice numbering is exposed: the series, the first and last numbers, the total, and cancellations must reconcile with the invoices you reported. Our guide on invoice numbering rules explains how to keep a clean series.

Credit and debit notes to registered customers go in Table 9B with the original invoice reference; notes to consumers are netted in Table 7. Details of when to issue them are in our credit note and debit note guide.

What goes in each table of GSTR-3B

GSTR-3B (Rule 61) is short but every box has a meaning.

• 3.1 Outward and reverse charge supplies. (a) Taxable outward supplies other than zero-rated, nil and exempt: total taxable value with IGST, CGST, SGST and cess. (b) Zero-rated (exports, SEZ). (c) Nil-rated and exempt. (d) Inward supplies liable to reverse charge: the value and tax you must pay as recipient. (e) Non-GST outward supplies (petrol, alcohol).
• 3.1.1 Supplies through e-commerce operators under Section 9(5): the operator reports (i), you report (ii) so the same sale is not taxed twice.
• 3.2 Inter-state supplies to unregistered persons, composition dealers and UIN holders, state by state. This must match Tables 5 and 7 of GSTR-1.
• 4 Eligible ITC. 4(A) credit available by category, 4(B) reversals, 4(C) net credit, 4(D) ineligible or reclaimed credit for information. Details in our input tax credit guide.
• 5 Exempt, nil-rated and non-GST inward supplies. Inter-state and intra-state values.
• 5.1 Interest and late fee. Interest you compute yourself; late fee is auto-calculated.
• 6.1 Payment of tax. Shows tax payable, credit used from the electronic credit ledger, and cash paid from the electronic cash ledger, with the order of set-off (IGST credit first, then CGST against CGST, SGST against SGST).

Since 2024 the liability in Table 3.1 is auto-populated from GSTR-1 and GSTR-1A, and the portal has moved towards locking these auto-populated values so corrections happen through GSTR-1A rather than by editing 3B. Check the current status of that locking on the portal; the practical rule is to get GSTR-1 right and treat 3B as a confirmation.

The monthly flow, step by step

Before the 11th (monthly) or 13th (QRMP with IFF):

1. Close the sales register for the month. Every tax invoice, credit note and debit note should be entered with the customer GSTIN, place of supply, HSN and rate-wise tax.
2. Prepare the GSTR-1 JSON with the offline tool or fill tables on the portal. Upload B2B invoices, B2C summaries, HSN summary and document summary.
3. Preview, check the totals against your register, and file with EVC or DSC.

Between the 14th and 20th:

4. Download GSTR-2B. Match purchase bills. Decide the eligible ITC and reversals.
5. Open GSTR-3B. Confirm auto-populated Table 3.1 from GSTR-1. If it is wrong, file GSTR-1A to correct it before proceeding.
6. Fill Table 4 with matched ITC and reversals, Table 3.1(d) with reverse charge liability, Table 5.1 with any interest.
7. Check the payable in 6.1. If cash is needed, create a challan (PMT-06) and pay through net banking or UPI. The amount reflects in the cash ledger in minutes.
8. Offset the liability and file.

Under QRMP the same steps apply, but for the first two months you skip GSTR-3B and pay the estimated tax through PMT-06 by the 25th. You may use the fixed sum method (35% of the tax paid in cash in the last quarter, or 100% of the last month's cash tax if you were monthly) or the self-assessment method (actual liability minus actual ITC). If you underpay under self-assessment, interest applies on the shortfall; the fixed sum method has no interest as long as the quarterly 3B is filed on time.

Nil returns

A period with no outward supplies, no ITC to claim and no reverse charge liability still needs a nil GSTR-1 and nil GSTR-3B. File on the portal by ticking the nil option and submitting with EVC, or by SMS from the registered mobile number to 14409 (NIL R1 for GSTR-1, NIL 3B for GSTR-3B, followed by the GSTIN and period in MMYYYY). A nil return still attracts late fees of ₹20 a day if delayed, capped at ₹500 per return, so do it on the first day of the month instead of waiting.

Due dates, late fees and interest at a glance

Late fee for GSTR-1 is now auto-populated in the next GSTR-3B. Interest at 18% per annum under Section 50 runs on the net cash liability from the due date to the payment date. Full details, including the caps for larger turnover, are in our late fees, interest and penalties guide. Use the GST late fee calculator to see the cost of a delayed return before you decide whether it can wait.

Two more time limits matter. Returns cannot be filed more than three years after their due date (Sections 37(5) and 39(11), enforced on the portal from 2025), so an old unfiled period must be dealt with now, not later. And amendments to a financial year's GSTR-1 close on 30 November of the following year.

A worked example: a Pune freelance designer under QRMP

Neha has a Maharashtra GSTIN, turnover of about ₹36 lakh, and bills mostly registered agencies. She opts for QRMP with IFF. For the July to September 2026 quarter:

Quarterly GSTR-3B, due 22 October (Maharashtra): total output ₹1,62,000, total ITC ₹23,500, net ₹1,38,500. Already paid through PMT-06: ₹83,500. Cash payable with the quarterly 3B: ₹55,000. Her clients saw July and August invoices in their 2B in the month after issue because of the IFF; without it they would have waited until October.

Had she used the fixed sum method and her previous quarter's cash tax was ₹1,20,000, each PMT-06 would be ₹42,000 (35%) regardless of actual sales, with the balance settled in the quarterly 3B.

A monthly routine you can keep

• 1st to 5th: enter all sales and purchase documents for the previous month; issue any credit notes for returns.
• 6th to 10th: reconcile the sales register with the invoice series (Table 13), fix HSN gaps, prepare GSTR-1 or IFF.
• 11th (or 13th): file GSTR-1 or IFF.
• 14th: download GSTR-2B, match purchases, follow up suppliers whose invoices are missing.
• 15th to 18th: prepare GSTR-3B, arrange cash for the payable.
• 20th (or 22nd/24th/25th): file GSTR-3B or pay PMT-06.
• Same day: save the filed return PDF, challan and 2B into a month folder.

For a full list of the compliance dates in a year, including TDS, advance tax and annual returns, see our small business compliance calendar.

Common mistakes

• Filing GSTR-1 from memory. If it does not match the invoice register, the document summary in Table 13 will not reconcile and customers will complain about missing credit.
• Putting B2B invoices in B2C. The customer's GSTIN was not entered on the invoice, so the sale went to Table 7 and the customer gets no credit. Verify GSTINs at invoicing.
• Wrong place of supply on inter-state B2C. Table 3.2 of 3B must match GSTR-1 by state.
• Claiming ITC not in 2B. Leads to a DRC-01C intimation and 24% interest on wrongly availed credit.
• Ignoring reverse charge. Freight paid to a GTA, advocate fees and imported services must be shown in 3.1(d) and paid in cash; the credit is available in the same 3B.
• Skipping PMT-06 under QRMP because "the return is quarterly". Interest accrues on the unpaid monthly amount.
• Using amendments to hide errors. Amend in Table 9 or 10 with the original reference; do not delete and re-add invoices under new numbers.
• Not saving proof. Keep the ARN, filed PDF and challan for every period; notices arrive years later.

How VyaparKit helps

The GST invoice tool builds a clean sales register with GSTIN, place of supply, HSN and rate-wise tax on every document, and FY-wise numbering that reconciles with Table 13. The purchase bill tool records inward invoices with an ITC flag, and the GST report presents outward supplies in GSTR-1 order and an ITC table for GSTR-3B Table 4. The GST due dates calendar and the GST late fee calculator keep the dates and the cost of missing them in front of you. VyaparKit does not file returns or fetch GSTR-2B; it prepares the data you copy into the portal or hand to your CA.

Next steps

• Decide monthly or QRMP based on your turnover and how many registered customers you have; opt in on the portal before the quarter starts.
• Set a fixed calendar: register close by the 5th, GSTR-1 by the 11th, 2B match on the 14th, 3B by the 20th.
• Make sure every invoice carries a verified customer GSTIN and place of supply before it is issued.
• File nil returns on the first of the month for any inactive period.
• Clear any return older than a few months now, before the three-year bar closes it permanently.