Every regular GST taxpayer files two returns again and again: GSTR-1 for sales and GSTR-3B for the summary and payment of tax. They are often mixed up, but they do different jobs. Getting both right and on time protects your input tax credit and keeps penalties away.
GSTR-1: the statement of your sales
GSTR-1 lists the outward supplies you made in the period: invoices to registered customers, sales to unregistered customers, exports, credit and debit notes and advances received. The details flow to your customers, who see them in their own GST statements (GSTR-2B) and use them to claim input tax credit. If you report an invoice wrongly or late, your customer may lose credit and ask you to correct it.
GSTR-3B: the summary and the payment
GSTR-3B is a summary return. It shows your total sales, the input tax credit you are claiming, any reverse charge liability and the net tax payable. The tax is paid when you file it. Claim credit only on what appears in your GSTR-2B, and make sure the sales figures agree with GSTR-1.
Due dates for monthly filers
- GSTR-1: the 11th of the following month.
- GSTR-3B: the 20th of the following month.
Due dates under the QRMP scheme
Taxpayers with turnover up to ₹5 crore can opt for the Quarterly Return Monthly Payment (QRMP) scheme. Returns are filed quarterly and tax is paid monthly.
- GSTR-1 (quarterly): the 13th of the month after the quarter ends.
- IFF (optional invoice upload for B2B sales): the 13th of the month after the first and second months of the quarter.
- PMT-06 (monthly tax payment): the 25th of the month after the first and second months of the quarter.
- GSTR-3B (quarterly): the 22nd or the 24th of the month after the quarter ends, depending on the state group. Karnataka falls in the 22nd group.
GSTR-1 vs GSTR-3B at a glance
- Purpose: GSTR-1 reports sales invoice by invoice. GSTR-3B is a summary of sales, credit and tax payable.
- Payment: no tax is paid with GSTR-1. Tax is paid when GSTR-3B is filed.
- Who it affects: GSTR-1 decides what your customers can claim. GSTR-3B decides what you pay and claim.
- Input tax credit: GSTR-3B credit should match your GSTR-2B statement.
Late fees and interest
- Late fee on GSTR-1 and GSTR-3B is ₹50 a day (₹25 CGST and ₹25 SGST), or ₹20 a day for nil returns, up to a cap that depends on your turnover.
- Interest on tax paid late is 18% a year, and 24% a year on input tax credit that was claimed wrongly.
- Unfiled returns can block your customers from claiming credit and can stop you from generating e-way bills.
Annual return
GSTR-9 is the annual return, due on 31 December after the end of the financial year. It is mandatory for regular taxpayers with aggregate turnover above ₹2 crore, and GSTR-9C applies above ₹5 crore.
Tips to stay compliant
- Upload invoices to the portal through the month so nothing is left for the last day.
- Reconcile purchases with GSTR-2B before filing GSTR-3B.
- File nil returns on time, even in months without sales.
- Keep a calendar of due dates and the payment dates for QRMP.
Need help?
SS Auditors files GSTR-1, GSTR-3B and annual returns for businesses across Bangalore. See GST return filing, GST annual return or contact us.
Last reviewed October 2026. This article is general information, not advice for your specific case. Due dates can be extended by notification, so confirm the current date on the GST portal.