GSTR-1 from Billing Data: A Simple Monthly Process for Shops

Updated: 30 October 2026

GSTR-1 is the return in which a regular GST taxpayer reports every sale (outward supply) made in a month or quarter. Your buyers' input tax credit depends on it, because the B2B invoices you report flow into their GSTR-2B. If your bills are already in a billing app, most of the work is done: GSTR-1 is simply your sales register, grouped the way the GST portal wants it.

Seedhi baat: agar har bill sahi GSTIN, HSN aur GST % ke saath bana hai, to GSTR-1 bharna sirf data ko sahi tables mein daalna hai. This guide explains those tables, the due dates, a monthly checklist and the mistakes that cause notices.

Who files GSTR-1 and when

Every regular GST registered person files GSTR-1. Composition dealers do not; they file CMP-08 and GSTR-4 instead (see the composition scheme guide).
Monthly filers: GSTR-1 is due by the 11th of the next month. For example, October sales are reported by 11 November.
QRMP filers (turnover up to ₹5 crore who opted for quarterly returns): GSTR-1 is due by the 13th of the month after the quarter. In the first two months of the quarter you may upload B2B invoices through the optional IFF (Invoice Furnishing Facility) by the 13th, so your buyers get credit sooner.
A nil GSTR-1 is still required for a month with no sales. Late fee is charged per day of delay (lower for nil returns), so file even when there is nothing to report.

Due dates can be extended by government notification. Always check the GST portal or your CA for the current month.

The GSTR-1 tables a shop actually uses

Where each kind of bill goes in GSTR-1
Table	What goes in it
4A – B2B	Every invoice to a buyer with a GSTIN, invoice by invoice: GSTIN, invoice number, date, value, place of supply, rate and taxable value
5 – B2CL	Inter-state invoices to unregistered buyers where the invoice value is more than ₹1 lakh, invoice by invoice
7 – B2CS	All other sales to unregistered buyers (local sales and small inter-state sales), as totals by place of supply and GST rate
8 – Nil / exempt	Sales of nil-rated, exempt and non-GST items
9B – Credit / debit notes	Notes issued in the period: CDNR for registered buyers, CDNUR for unregistered (B2CL) buyers
12 – HSN summary	Sales grouped by HSN code, unit and rate, reported separately for B2B and B2C
13 – Documents issued	Serial number range of invoices, credit notes and other documents issued, with cancelled count

Scroll sideways to see all columns.

The ₹1 lakh B2CL limit applies from August 2024 (it was ₹2.5 lakh earlier).

Monthly checklist before you prepare GSTR-1

Make sure every sale of the month is billed. Cash sales written on paper and never entered are the most common gap.
Check B2B bills: the buyer GSTIN must be correct (15 characters, with the right state code). A wrong GSTIN means your buyer does not get credit and will call you.
Check the place of supply. Local sale = CGST + SGST; sale to another state = IGST. A wrong tax type cannot be fixed by changing amounts later; it needs a credit note and a fresh bill.
Check that every item line has an HSN or SAC code and the correct GST rate. See HSN code and GST rate setup.
List cancelled invoice numbers. They should stay cancelled in your books (do not delete them), and they are reported in the documents issued table.
Enter credit notes for returns and post-sale discounts in the same month you issue them.

Preparing GSTR-1 from BizBahi

In BizBahi go to More → GSTR-1 / 3B export, choose the month and download the file. BizBahi groups your saved bills into sheets that follow the column layout of the GSTN Returns Offline Tool: b2b, b2cl, b2cs, cdnr, cdnur, exemp, hsn (split B2B and B2C) and docs. It also shows warnings, for example a bill line with no HSN code or a buyer GSTIN that is not valid.

You (or your CA) then check the figures and upload or type them on the GST portal. BizBahi does not connect to the GST portal and does not file the return for you; it is filing assistance. The GSTR-1 / 3B export is part of the paid plans and the 7-day trial for new accounts. Your bills keep their GST details on the free plan too.

Filing on the GST portal (short version)

Log in at gst.gov.in → Services → Returns → Returns Dashboard, and choose the financial year and period.
Open GSTR-1 and either fill each table online or import the JSON prepared with the offline tool.
Click Generate Summary and compare the totals with your sales register for the month.
File with DSC or EVC (OTP). After filing, B2B invoices appear in your buyers’ GSTR-2B.

Common GSTR-1 mistakes

Reporting a B2B sale as B2C because the GSTIN was not typed on the bill. The buyer loses credit until you amend it.
Mismatch between GSTR-1 and GSTR-3B. The tax in GSTR-3B should match the outward supplies in GSTR-1 for the same period; large gaps lead to notices.
Forgetting credit notes, so the tax paid stays higher than it should be.
Using one GST rate for all items or leaving HSN blank, which makes the HSN summary wrong.
Editing an invoice after it was reported. Corrections are made through amendment tables or credit/debit notes, not by changing the old bill.

Frequently asked questions

What is the due date of GSTR-1?

For monthly filers, the 11th of the next month. For QRMP (quarterly) filers, the 13th of the month after the quarter, with the optional IFF for B2B invoices by the 13th of the first two months.

Do I report small cash sales one by one?

No. Sales to unregistered buyers, except inter-state invoices above ₹1 lakh, are reported in B2CS as totals by place of supply and GST rate.

Can BizBahi file GSTR-1 directly?

No. BizBahi prepares month-wise GSTR-1 sheets and warnings from your bills. You or your CA check them and file on the GST portal.

Do I need to file GSTR-1 if there were no sales?

Yes. File a nil GSTR-1 for that period, otherwise a late fee applies and your GSTR-3B filing may be affected.

How do I correct a wrong GSTIN after filing?

Use the amendment table (9A) in a later GSTR-1, within the time allowed, and tell the buyer. Do not edit the original bill in your books.

Some features need a paid plan — see Pricing. All features are listed on the Features page.

Download BizBahi free Install guide