How to file GSTR-1: due dates, tables and the mistakes that cost you
By the bookledger team· ·7 min read
GSTR-1 is the return where you declare what you sold. It decides what your buyers can claim as input tax credit — which is why an error here stops being your problem and becomes theirs, and why you hear about it.
This is the practical version: when it is due, what belongs in which table, and the four mistakes that generate the most notices.
When GSTR-1 is due
Which schedule you are on depends on your aggregate turnover in the previous financial year.
| You are | You file | Due |
|---|---|---|
| Turnover above ₹5 crore | Monthly GSTR-1 | 11th of the following month |
| Up to ₹5 crore, on QRMP | Quarterly GSTR-1 | 13th of the month after the quarter |
| On QRMP, months 1 and 2 | IFF (optional) | 13th of the following month |
QRMP means Quarterly Return, Monthly Payment. The return is quarterly; the tax is not. You still pay every month, by challan in PMT-06, for the first two months of the quarter. Confusing the two is how people end up paying interest on a return they believed was not yet due.
The IFF is optional, and usually worth using
The Invoice Furnishing Facility lets a QRMP filer upload B2B invoices only during the first two months of a quarter. Nothing obliges you to use it. But if you skip it, a customer who bought from you in April sees nothing in their credit statement until you file in July.
If you sell to businesses that watch their ITC — and most do — the IFF is the difference between a quiet sale and a phone call. Invoices filed through it are not repeated in the quarterly return.
What goes in which table
Most of GSTR-1 is one question asked repeatedly: is this sale listed invoice by invoice, or summarised?
| Sale | Table | Reported |
|---|---|---|
| To a registered business (B2B) | 4 | Invoice by invoice |
| Inter-state to a consumer, above ₹2.5 lakh | 5 | Invoice by invoice |
| Everything else to consumers | 7 | Summarised, rate-wise |
| Credit and debit notes | 9B | Note by note |
| Advances received | 11A | Summarised |
| HSN summary | 12 | Summarised by HSN and rate |
The rule of thumb: if the buyer can claim credit, the invoice is listed. A shop selling to walk-in customers reports a rate-wise total for the month. A distributor selling to fifty retailers reports fifty invoices.
HSN in Table 12: check your digit count
HSN is no longer a free-text field, and how many digits you owe depends on turnover:
- —Up to ₹5 crore: 4 digits, mandatory since May 2025.
- —Above ₹5 crore: 6 digits minimum, mandatory since November 2022.
The portal now supplies HSN from a dropdown and fills the description itself — you cannot type one in. That kills a whole category of typo, but it also means any product in your own catalogue carrying an invented or truncated HSN will match nothing when you export. Fix the catalogue before the deadline, not during it.
Four mistakes that cost the most
1. Filing GSTR-3B before GSTR-1
You cannot. GSTR-1 for a period must be filed first. Treat GSTR-1 as the source and 3B as the summary that follows, because that is the order the portal enforces.
2. Fixing an error in the wrong place
Since July 2024 there is GSTR-1A, an amendment form open from the moment you file GSTR-1 until you file GSTR-3B for the same period. Inside that window a correction is clean. Miss it and the same correction becomes an amendment in a later period — visible to your buyer, and to anyone reconciling.
3. Treating a nil return as nothing to do
A nil GSTR-1 still has to be filed and still carries a late fee: ₹20 per day, capped at ₹500. A return with liability runs ₹50 per day, capped at ₹10,000. Neither is large. Both are avoidable, and both compound quietly across a year.
4. Reporting a B2B sale as B2C
The expensive one, because you will not notice. Your figures are right, your tax is right, and your customer simply never sees the credit. They find out when they reconcile GSTR-2B — usually weeks later, usually loudly.
A working sequence
- 01Check every B2B invoice carries the buyer's GSTIN. A missing GSTIN is exactly what turns a B2B sale into a B2C one.
- 02Confirm HSN codes exist at the digit count your turnover requires.
- 03Reconcile your sales register against the portal before filing, not after.
- 04File GSTR-1, then GSTR-3B, in that order.
- 05If something is wrong, use GSTR-1A before filing 3B.
Where software actually helps
None of this is difficult. It is repetitive, and it fails at the edges — a missing GSTIN, an HSN nobody filled in, a credit note recorded as a discount. Those are catalogue and data-entry problems, and they are far cheaper to prevent than to amend.
bookledger captures GSTIN and HSN when the customer and the item are created, keeps B2B and B2C separated as you bill, and exports GSTR-ready summaries so filing becomes a reconciliation rather than a rebuild. It works offline and syncs when you are back — which matters when the deadline is the 11th and the connection is not.
Common questions
What is the due date for GSTR-1?
The 11th of the following month if you file monthly; the 13th of the month after the quarter if you are on QRMP.
Can I file GSTR-3B before GSTR-1?
No. GSTR-1 for that period must be filed first.
How do I correct a filed GSTR-1?
With GSTR-1A, any time between filing GSTR-1 and filing GSTR-3B for the same period.
How many HSN digits do I need?
Four up to ₹5 crore of turnover, six or more above it — chosen from the portal's dropdown.
Next, the other half of the same problem: why input tax credit gets rejected even when the invoice is perfect.
Last reviewed 27 September 2026. GST due dates, thresholds and late fees are changed by notification from time to time. Check the current position on the GST portal, or with your accountant, before relying on a figure here.