GSTR-1 is due on the 11th of the following month for monthly filers, and GSTR-3B is due on the 20th. Taxpayers on the QRMP scheme file GSTR-1 by the 13th after the quarter and GSTR-3B by the 22nd or 24th depending on their state category, while still paying monthly tax through PMT-06 by the 25th. Due dates are occasionally extended by CBIC notification for specific return types or taxpayer categories, so the date shown on your GST portal dashboard should always be treated as the final word.

Yes. GST returns must be filed even with nil tax liability, and a late fee of ₹20 per day still applies to a delayed nil return. There's no exemption for zero-activity months — the filing obligation is tied to your GST registration, not your transaction volume for that period. We see this trip up seasonal businesses and dormant registrations more than any other GST mistake.

The late fee is ₹50 per day for GSTR-1/GSTR-3B with tax liability (capped at ₹5,000), ₹20 per day for nil returns (capped at ₹2,000), plus 18% per annum interest on any outstanding tax from the due date until payment. If excess Input Tax Credit was claimed and used, interest rises to 24% per annum. Late fee and interest both apply together — paying the tax on time doesn't waive the late fee if the return itself is filed after the deadline.

QRMP lets businesses with turnover up to ₹5 crore file GSTR-1 and GSTR-3B quarterly instead of monthly, while still paying tax every month via PMT-06. It reduces the number of returns you file from 24 to 8 a year, but tax cash flow still has to be tracked monthly, and the Invoice Furnishing Facility needs discipline in months 1 and 2 of the quarter if your buyers need early ITC visibility. Whether it's worth it depends on your buyer relationships and cash flow pattern — worth a conversation before switching.

GSTR-9 is mandatory for taxpayers with annual turnover above ₹2 crore, and GSTR-9C, a CA/CMA-certified reconciliation statement, applies above ₹5 crore turnover. Both consolidate the year's monthly or quarterly filings into a single annual return, and discrepancies between GSTR-9 and the monthly returns are a common trigger for departmental scrutiny — which is why reconciliation before filing matters more here than almost any other return.

Reconcile the specific invoices flagged against your GSTR-2B and purchase register before drafting any response, since most ITC mismatch notices stem from timing differences or supplier-side filing gaps rather than genuine errors on your part. A poorly drafted or rushed reply can turn a routine mismatch into a demand order. This is exactly the kind of notice where a properly reconciled, professionally worded reply within the given timeline matters far more than replying quickly.

No — GST returns can only be filed up to three years from the original due date, after which the filing window is permanently closed on the portal for that tax period. If you have pending returns from several years ago, this is a genuine deadline, not a formality, and it's worth checking your filing history against this cutoff sooner rather than later.