What is GSTR-1 in GST? Filing Process, Practical Use Cases & SAP Automation

As per Section 37 of the CGST Act, 2017, every registered person (other than those specifically exempted) is required to furnish details of outward supplies in the prescribed form. Since, under Section 51 (Tax Deduction at Source) and Section 52 (Tax Collection at Source) of the CGST Act, a registered person is either liable to pay tax or collect tax, it becomes mandatory to report all outward supplies, including tax invoices, debit notes, credit notes, and zero-rated supplies (exports and SEZ supplies).

The Outward supplies data which is filled in GSTR-1 forms the base of the auto-population of GSTR-2B, which directly impacts the Input Tax Credit(ITC) eligibility of the recipient. Hence, accuracy, timeliness, and reconciliation in GSTR-1 filing are critical for GST compliance.

What is GSTR-1?

As per Section 37 of the CGST Act, 2017, read with Rule 59 of the CGST Rules, 2017, every registered person (other than specified exceptions) is required to furnish details of outward supplies in Form GSTR-1.

The return contains the following information as mandated under the CGST Act 2017:

1. Invoice-wise Details of Taxable Outward Supplies

As per Section 37(1) of the CGST Act and Rule 59(1)(a), GSTR-1 should have invoice-wise details of all taxable outward supplies made to registered persons (B2B), including:

• GSTIN of recipient
• Invoice number & date
• Taxable value
• Applicable tax rate and tax amount

Whenever you are filing this section of GSTR-1 make sure that the GSTIN is valid you can check the same by SEPFUST’s GSTIN Validator.

2. Zero-Rated Supplies (Exports & SEZ)

As per Section 16 of the IGST Act, 2017, read with Rule 59(1)(b) of the CGST Rules, details of zero-rated supplies must be reported in GSTR-1, including:

• Export of goods/services (with or without payment of tax)
• Supplies made to SEZ units or developers
• Shipping bill details, port code, and LUT/Bond reference

3. Nil-Rated, Exempt & Non-GST Supplies

As per Rule 59(1)(e), registered persons must disclose summary-level details of:

• Nil-rated supplies
• Exempt supplies
• Non-GST outward supplies

This reporting ensures transparency in outward supplies even where no tax is payable.

4. Debit Notes & Credit Notes Issued

As per Section 34 of the CGST Act, read with Rule 59(1)(j), details of:

• Debit Notes issued for additional tax liability
• Credit Notes issued due to post-supply adjustments
• must be reported in GSTR-1 with original invoice linkage.

5. Advances Received and Adjusted

As per Section 12 and Section 13 of the CGST Act, read with Rule 59(1)(f):

• Advances received for future supplies (where applicable)
• Adjustments of advances against invoices issued
• must be reported to correctly determine the time of supply.

6. HSN-wise Summary of Goods and Services

As per Rule 59(1)(l) read with Notification No. 78/2020–Central Tax, GSTR-1 must include an HSN/SAC-wise summary, covering:

• HSN/SAC code
• Description of goods/services
• Total quantity
• Taxable value and tax amounts

This enables data analytics, compliance monitoring, and audit trail for GST authorities.

Download GSTR-1 Format - Click Here

Who is Required to File GSTR-1?

Any registered taxpayer under GST who has outward supplies, except:

• Composition taxpayers
• Input Service Distributors (ISD)
• Non-resident taxable persons (NRTP)

GSTR-1 Filing Frequency & Due Dates

Detailed Structure of GSTR-1

Key Tables in GSTR-1

Why GSTR-1 is Critical for Businesses

1. ITC Availability for Customers

Not filing or incorrect filing GSTR-1 timely will lead to:

• Non-reflection in GSTR-2B
• Vendor follow-ups
• Business relationship issues

2. GST Notices & Compliance Risks

In case there is a Mismatch as per the Invoices reported in E-Invoices or GSTR3B, you can get a GST Notice from the Department.

• GSTR-1 vs GSTR-3B
• GSTR-1 vs E-Invoice data
• can trigger GST notices and audits.

3. Export Refund Dependency

For every exporter it is required to file the GSTR-1 on time and with accurate information of their Exports Invoices and other invoices. And this is how they can take care of the following:

• IGST refunds
• LUT/Bond compliance
• Shipping bill matching

Common GSTR-1 Errors

While filing the GSTR-1 it is expected not to make errors as it will be very difficult to track those errors and rectify it making it not an expected scenario in your business. But still there are some common mistakes business mostly do:

• Incorrect GSTIN of recipient
• Wrong place of supply
• Invoice number duplication
• HSN/SAC mismatch
• Difference between GSTR-1 & GSTR-3B

How SAP Automation Solves GSTR-1 Challenges

1. Direct SAP → GST Data Flow

SAP Automation will allow you to directly post your invoices in the GSTR1 without any manual intervention, it will automatically extract the Invoices data, put rule based validation and provide you with the GST Compliant data Structure.

2. Built-in GST Validations

It is very important to handle the invoices which have some errors beforehand so that wrong invoices cannot go in the GSTR-1, automation through SAP will allow you to put extra validations as per your business requirement and GSTIN Validations like:

• GSTIN structure
• Tax rate accuracy
• HSN/SAC mapping
• POS vs GSTIN state logic

3. Error-Free JSON Generation

In order to file GSTR-1, JSON file need to import in the GST Process, some business having multi state operations and large quantity of the invoices it is very difficult for them to manually do all this, but the SAP automation will help you to streamline the whole flow and provide you with GST portal-ready JSON

• No manual Excel dependency
• Faster uploads

4. Reconciliation with GSTR-3B & 2B

In order to avoid mismatches it is very important to keep on performing reconciliations, SAP Automation will allow you to reconcile your data with Realtime dataset available in your SAP or in any ERP or Software. This will allow you to check following points:

• Outward supply vs tax liability check
• Customer ITC reflection assurance

How SEPFUST GST Software & SAP Automation Help

SEPFUST GST Software is not only best fit for SAP Users with all possible SAP Automation and customizations provided, it also has the capability to fulfill all business needs by providing the end to end GST Return filing support.

Key Capabilities

• SAP-integrated GSTR-1 automation
• Invoice-level validations before upload
• Export & SEZ supply handling
• GSTR-1 vs GSTR-3B reconciliation
• Audit-ready reports
• Cloud-hosted & secure architecture

Business Benefits

• 90% reduction in manual effort
• Faster filing cycles
• Zero dependency on third-party utilities
• Improved vendor & customer trust
• Reduced GST notices

Conclusion

GSTR-1 is not just a Return it is the foundation compliance of GST because ITC flow across the supply chain. Manual processes increase risk, delay filings, and expose businesses to compliance failures.

With SEPFUST GST Software and SAP Automation, businesses can automate GSTR-1 filing, eliminate errors, ensure timely compliance, and stay audit-ready—all while integrating seamlessly with existing SAP systems.

Frequently Asked Questions (FAQs)

Q1. Can GSTR-1 be revised after filing?

No. GSTR-1 cannot be revised, but errors can be corrected in subsequent returns.

Q2. What happens if GSTR-1 is filed late?

Late fees:

• ₹50/day (₹20/day for Nil returns)
• Maximum ₹10,000

Q3. Is GSTR-1 mandatory even if there are no sales?

Yes. Nil GSTR-1 must be filed.

Q4. How does GSTR-1 impact GSTR-2B?

Invoice details from GSTR-1 auto-populate into the recipient’s GSTR-2B for ITC eligibility.

Q5. Can SAP automate GSTR-1 filing?

Yes. With SAP automation solutions like SEPFUST, GSTR-1 can be fully automated from data extraction to GST portal upload.