GSTR-1 for retailers: what goes where, and a month-end checklist

GSTR-1 for retailers in short

GSTR-1 is the return of your sales. A retail shop reports its sales to registered buyers bill by bill, its small consumer sales as rate-wise and state-wise totals, its credit notes, an HSN summary and the serial numbers of documents issued. Monthly filers file by the 11th of the next month. Quarterly filers under QRMP file by the 13th of the month after the quarter.

What you declare in GSTR-1 now fills the tax liability in your GSTR-3B, and that figure is locked. So mistakes in GSTR-1 flow straight into the tax you pay. The rules below are as of October 2026.

Which sale goes in which table

The ₹1 lakh line for B2CL

Notification 12/2024-Central Tax lowered the B2CL limit in Table 5 from ₹2.5 lakh to ₹1 lakh. So an inter-state sale of more than ₹1 lakh to an unregistered buyer is reported invoice by invoice. A local sale of any value to an unregistered buyer still goes in B2CS.

An example

Take a supermarket in Coimbatore in one month:

• 48 invoices to hotels and shops with GSTINs go to Table 4.
• One ₹1.4 lakh sale of a freezer delivered to a buyer in Kerala without a GSTIN goes to Table 5.
• Thousands of counter bills are added up by rate (5%, 18% and so on) and go to Table 7 with Tamil Nadu as the place of supply.
• Loose vegetables and other nil-rated sales go to Table 8.
• Returns from B2B customers, with credit notes, go to Table 9B.
• The HSN totals go to Table 12, split B2B and B2C. Bill number ranges go to Table 13.

Monthly filing, QRMP and IFF

Businesses with aggregate turnover up to ₹5 crore can opt for QRMP (Quarterly Return, Monthly Payment). Under QRMP:

• You file GSTR-1 and GSTR-3B once a quarter.
• You pay tax every month, by the 25th of the next month, for the first two months of the quarter.
• For those first two months, you can upload B2B invoices through the Invoice Furnishing Facility (IFF). IFF is optional, open up to the 13th of the next month, and limited to ₹50 lakh of invoice value a month.

IFF matters when your B2B buyers want their input credit every month. If most of your sales are counter sales, QRMP saves work. Your CA can tell you which suits your shop.

Due dates

The government sometimes extends these dates. Check the GST portal each month. Also note that a return cannot be filed once three years have passed from its due date. GSTN has been blocking such old returns on the portal in stages since 2025.

How GSTR-1 flows into GSTR-3B

Table 3 of GSTR-3B, your outward tax liability, is filled automatically from GSTR-1, GSTR-1A and IFF. From the July 2025 tax period, these auto-filled values cannot be edited in GSTR-3B. GSTN announced this hard lock in its advisory of 7 June 2025.

If you find a mistake after filing GSTR-1, correct it in GSTR-1A for the same period, before you file GSTR-3B. GSTR-1A is an optional form introduced in 2024 for this purpose. After GSTR-3B is filed, corrections go into a later GSTR-1 as amendments.

The GST Council has recommended further return reforms, with law changes expected from April 2027. Watch the GST portal for changes to the GSTR-1 form.

How billing software data maps to GSTR-1

A good billing system already holds everything GSTR-1 needs. The mapping is:

• Customer GSTIN on the bill decides B2B (Table 4) or B2C (Table 5 or 7).
• Customer state decides the place of supply, and so whether the sale is inter-state.
• Item GST rate gives the rate-wise totals for B2CS.
• Item HSN and unit give the Table 12 summary. See our HSN code guide.
• Sales returns with credit notes go to Table 9B for registered buyers, or reduce B2CS for consumers.
• Bill number series give Table 13.
• E-invoices fill B2B and credit note tables automatically, if you are under e-invoicing. See e-invoicing under GST.

Problems come from data, not from the form. If the GSTIN, state, rate or HSN on the bill is wrong, the return will be wrong.

Month-end checklist for a shop

1. Make sure every counter's bills for the month are synced and none are on hold.
2. Check cancelled bills are marked cancelled, not deleted.
3. Run a B2B sales list. Check each GSTIN, name and state against the buyer's registration.
4. Look for B2C bills that should have been B2B because the buyer gave a GSTIN later.
5. Check inter-state sales: IGST charged, correct state, and any above ₹1 lakh to unregistered buyers listed for B2CL.
6. Match the rate-wise sales report with total sales in your books.
7. Run the HSN summary. Look for blanks, wrong digits and units that do not match.
8. List credit notes. Each should refer to its original invoice.
9. Note the first and last bill numbers of each series for Table 13.
10. If you are under e-invoicing, check every B2B invoice has an IRN.
11. Upload, review the summary on the portal, then file. Correct any mistake through GSTR-1A before filing GSTR-3B.

Common GSTR-1 errors

• Wrong place of supply. Charging CGST and SGST on goods delivered to another state, or showing the customer's home state for a walk-in counter sale where the goods were handed over in your shop.
• Missing or wrong GSTIN. A B2B sale reported as B2CS. The buyer loses credit and will ask you to amend.
• HSN mismatch. Table 12 totals that do not match Tables 4 to 10, or HSN codes with fewer digits than required.
• Credit notes in the wrong place. B2B returns netted off in B2CS instead of reported in Table 9B.
• Nil-rated sales left out. Table 8 left blank in a grocery shop that sells loose staples.
• Gaps in Table 13. Number ranges that skip or overlap across counters.
• Late filing. Late fees run daily, and your B2B buyers cannot see the credit until you file.

Doing this in Cartix Prime

GST reports are on every plan. On the Gold plan, Cartix Prime prepares GSTR-1 and GSTR-3B ready for filing or for your CA, and handles e-invoices and e-way bills. Bills carry the customer GSTIN, HSN and GST by rate, so the tables come from the bills themselves. See GST billing software.