How to File GSTR-1: Step-by-Step Guide for FY 2026-27

Who Must File GSTR-1?

GSTR-1 must generally be filed by normal registered taxpayers, casual taxable persons, and SEZ units or developers registered as regular taxpayers. Businesses moving from the composition scheme to the regular scheme must also file it for the applicable period. Certain taxpayers use a different GST return:

GSTR-1 Filing Frequency and Due Dates

Taxpayers with aggregate annual turnover above ₹5 crore are required to file GSTR-1 monthly.

Eligible taxpayers with PAN-based aggregate annual turnover up to ₹5 crore may opt for the Quarterly Return Monthly Payment scheme . Under QRMP, both GSTR-1 and GSTR-3B are filed quarterly, while tax is paid monthly for the first two months through Form GST PMT-06.

Turnover up to ₹5 crore only creates eligibility for QRMP. It does not automatically make a taxpayer a quarterly filer. The following are the standard statutory due dates.

A different date applies only where the Government issues a specific extension.

Key GSTR-1 Tables and Reporting Rules

Key GSTR-1 Tables

Current B2C Large Threshold

Under the GSTN GSTR-1 filing guidance applicable from the August 2024 return period, an interstate supply to an unregistered recipient is reported as B2C Large when the invoice value exceeds ₹1 lakh.

Interstate B2C invoices of ₹1 lakh or less, as well as all intrastate B2C supplies, are reported in Table 7.

Table 12 and Table 13 Requirements

Under the GSTN advisory on Table 12 and Table 13 reporting, the following requirements apply from the May 2025 return period.

Table 12: HSN or SAC Summary

• AATO up to ₹5 crore: report at least four-digit HSN codes.
• AATO above ₹5 crore: report at least six-digit HSN codes.
• Select HSN or SAC codes from the portal dropdown.
• Report B2B and B2C summaries separately.

Table 13: Documents Issued

Table 13 is mandatory where data is reported in Tables 4, 5, 6, 7, 8, 9, 10, 14, or 15. Report the applicable document series, serial-number range, total documents issued, and cancelled documents.

Before filing, reconcile Table 12 with the outward-supply records and ensure that every applicable document series is accounted for in Table 13.

What You Need Before Filing GSTR-1

Before opening the return, close the sales register and organize the period’s invoices, credit and debit notes, e-invoice records, and prior-period amendments.

Confirm that customer GSTINs, place of supply , tax rates, and HSN or SAC codes are available for review. The invoice-level records should also reconcile with the taxable value and tax amounts in the books.

Prepare GSTR-1 from reconciled transaction-level records, not only from consolidated turnover totals.

How to File GSTR-1 on the GST Portal

Step 1: Log In and Select the Return Period

Visit https://www.gst.gov.in/ and sign in using the credentials for the relevant GSTIN. Go to Services > Returns > Returns Dashboard. Select the financial year, quarter where applicable, and return filing period, then click Search.

Step 2: Open GSTR-1

Find the GSTR-1 tile and choose the appropriate preparation method:

●     Prepare Online: Enter, edit, or review records directly on the GST Portal.

●     Prepare Offline: Upload a JSON file prepared using the GST offline utility or compatible accounting software.

Step 3: Review Auto-Populated E-Invoice Records

For taxpayers covered by e-invoicing, eligible records are auto-populated from the Invoice Registration Portal into the relevant GSTR-1 tables. The transfer may take up to two days. Therefore, invoices generated close to the filing date may not appear immediately.

Before proceeding, compare the auto-populated records with the sales register and IRP data . Check the invoice number and date, recipient GSTIN, taxable value, tax amounts, place of supply, credit and debit notes, and canceled IRNs.

Auto-populated e-invoice records can be edited or deleted in GSTR-1. However, editing a record may remove its IRP source indication on the portal. The sales register, IRP records, and final GSTR-1 should remain consistent.

Step 4: Enter or Upload the Applicable Records

Enter or upload the transactions in the applicable GSTR-1 tables described above. After processing the records, check that each transaction is in the correct table and that no invoice or note has been omitted or reported twice.

Step 5: Generate and Review the GSTR-1 Summary

After saving all applicable records, select Generate Summary. The portal automatically refreshes the summary approximately every 30 minutes. A manual summary can generally be generated once every 10 minutes.

Review the summary against the books and resolve any differences before moving to the filing stage. Pay particular attention to:

• Total taxable turnover and tax liability
• CGST, SGST, UTGST, and IGST classification
• B2B recipient-wise totals
• B2C state-wise totals
• Export and SEZ supplies
• Credit and debit notes
• HSN or SAC totals
• Document-series totals

Step 6: Proceed to Filing

Select Proceed to File/Summary. The current portal process does not include a separate Submit stage. Review the consolidated and recipient-wise summary, then download the PDF and retain it with the filing working papers.

Before filing GSTR-1 confirm that the applicable tables are complete, the generated summary matches the final sales register, identified corrections are complete, the PDF summary has been reviewed, and the authorised signatory is available.

Step 7: File GSTR-1

Select File Statement, complete the declaration, and choose the authorised signatory. File the return using the option enabled for the GSTIN:

• File with DSC
• File with EVC

The GST Portal permits filing through EVC in applicable cases. Therefore, check the available signing options for the GSTIN rather than assuming that a DSC is mandatory solely because the taxpayer is a company or LLP.

Step 8: Save the Filing Proof

After successful filing, the return status changes to Filed, and an Acknowledgment Reference Number is generated. Filing confirmation is also sent to the authorised signatory. Download and retain:

• The filed GSTR-1
• The ARN
• The final summary
• Supporting reconciliation working papers

How to File Nil GSTR-1

A Nil GSTR-1 can be filed only when there are no outward supplies, amendments, credit or debit notes, or taxable service advances to report for the period. For SMS filing, there must also be no saved or submitted GSTR-1 data on the portal.

File Nil GSTR-1 Online

Log in to the GST Portal and go to: Services > Returns > Returns Dashboard > GSTR-1 > Prepare Online

Select File Nil GSTR-1, proceed to filing, and verify the return using the DSC or EVC option available for the GSTIN.

File Nil GSTR-1 by SMS

Send the following message from the registered mobile number of an authorised signatory to 14409: NIL R1 GSTIN MMYYYY

For example, for March 2026: NIL R1 27AAAAA0000A1Z5 032026

The system will send a six-digit verification code. Confirm the filing by replying:

CNF R1 CODE

The verification code is valid for 30 minutes and can be used only once. After successful confirmation, an ARN is generated, and the return status changes to Filed.

How IFF Works Under QRMP

Filed IFF records can be considered in the recipient’s GSTR-2B for the first two months of the quarter, subject to the recipient’s IMS action. This avoids waiting for the quarterly GSTR-1. IFF may be used for:

• B2B invoices reported in Tables 4A, 4B, 4C, 6B and 6C
• Credit and debit notes issued to registered recipients in Table 9B
• Permitted amendments reported through Tables 9A and 9C

IFF does not cover B2C supplies, exports, or the remaining GSTR-1 tables. These are reported in the quarterly GSTR-1. IFF for M1 and M2 is generally due by the 13th of the following month.

Using IFF is optional. However, if an IFF has been submitted, it must be filed before the quarterly GSTR-1 can be filed. Documents already filed through IFF should not be entered again in the quarterly return.

How to Correct GSTR-1 After Filing

GSTR-1A allows permitted corrections to the current tax period after GSTR-1 has been filed. The correction route depends on when the error is identified and what information needs to be changed.

Key Rules for GSTR-1A

GSTR-1A becomes available after GSTR-1 is filed or its due date has passed, whichever is later. It remains available only until GSTR-3B for the same tax period is filed.

It can be filed once for a tax period, and there is no Nil GSTR-1A. The recipient GSTIN cannot be changed through GSTR-1A; instead, it must be corrected through the applicable amendment process in a subsequent GSTR-1.

Records added or amended through GSTR-1A are reflected in the recipient’s next tax period's GSTR-2B.

Note: Auto-populated GSTR-3B values currently remain editable. However, specified variances are highlighted and may generate warnings. A GSTR-1 or IFF liability that exceeds the liability paid through GSTR-3B beyond the system threshold may also result in Form GST DRC-01B.

How GSTR-1 Filing Affects the Buyer’s ITC

Invoices and notes saved in GSTR-1, IFF, or GSTR-1A become available to the recipient through IMS. However, only records filed by the supplier are considered when generating GSTR-2B.

Eligible records accepted or treated as accepted are included in GSTR-2B. Late filing, an incorrect GSTIN, a missing invoice, or an unreported credit note can therefore delay ITC or create a difference between the buyer’s purchase register and GSTR-2B .

Late Filing Consequences and Filing Limits

GSTR-1 Late Fee

Late fee is calculated from the day after the applicable due date, subject to any period-specific waiver or relief notification.

Notification No. 20/2021-Central Tax, dated 1 June 2021, rationalized the maximum late fee for delayed GSTR-1 filing. These are the combined central and corresponding state or Union territory amounts. Check whether any specific waiver or extension applies to the relevant return period before finalizing the liability.

Three-Year Filing Restriction

Section 37(5) of the CGST Act generally prevents a registered person from furnishing GSTR-1 more than three years after its due date.

However, the section also allows the Government, on the GST Council’s recommendation, to permit specified registered persons or classes of persons to file after that period through notification.

Common GSTR-1 Mistakes and How to Avoid Them

Even when the portal filing steps are followed correctly, errors in the underlying invoice data can lead to tax differences, delayed buyer ITC, and later amendments.

1. Entering an Incorrect Recipient GSTIN

A wrong GSTIN can make the invoice available to the wrong recipient or prevent the actual buyer from seeing it in their GST records. Validate the GSTIN against the customer master before filing. This is especially important because the recipient GSTIN cannot be changed through GSTR-1A.

2. Using the Wrong Place of Supply

An incorrect place of supply may cause IGST to be reported instead of CGST and SGST, or vice versa. Check the nature of the transaction, recipient location, and applicable place-of-supply rules before finalising the return.

3. Reporting B2C Invoices in the Wrong Table

Using the older ₹2.5 lakh threshold can place interstate B2C invoices in the wrong table. Apply the current ₹1 lakh threshold when classifying B2C Large invoices.

4. Missing or Duplicating Invoices

Invoices may be omitted during manual entry or duplicated when data is uploaded from multiple sources. Reconcile the invoice count and taxable value in GSTR-1 with the sales register before filing. Also, review cancelled and revised invoice numbers separately.

5. Not Reconciling E-Invoice Records

Compare the sales register with IRP and GSTR-1 data, particularly for canceled IRNs and records generated close to the filing date.

6. Omitting Credit or Debit Notes

Missing credit notes can leave the original taxable value unchanged in the GST records. Missing debit notes can understate outward liability.

Reconcile the return with the credit-note and debit-note registers, including notes issued for sales returns, discounts, and invoice revisions.

7. Using Incorrect or Incomplete HSN or SAC Details

Select the correct HSN or SAC from the portal dropdown and reconcile Table 12 with the outward-supply records.

8. Leaving Table 13 Incomplete

Where data is reported in Tables 4, 5, 6, 7, 8, 9, 10, 14 or 15, ensure that Table 13 includes the applicable document series and cancellations.

9. Filing GSTR-3B Before Review

Filing GSTR-3B closes GSTR-1A for that period. Complete the current-period review before filing GSTR-3B.

Conclusion

Accurate GSTR-1 filing depends on the quality of the records behind the return. Invoice data, tax classifications, e-invoice records, credit and debit notes, and HSN summaries should be complete and reconciled before filing.

The final review should be completed before GSTR-3B is filed, so permitted current-period errors can still be corrected through GSTR-1A. This helps reduce tax differences, buyer ITC mismatches, and avoidable amendments later.

Businesses handling a high volume of transactions can use BUSY accounting software to maintain sales records, prepare GST return data, and simplify reconciliation. The final return should still be reviewed by the responsible accountant, finance team, or tax professional before filing.