GST Reconciliation • GSTR-1 Return Filing Guide

GSTR-1 Return Filing Guide: Complete Table-wise Explanation, Examples & Common Mistakes

A practical GSTR-1 guide for accountants, finance teams, tax professionals and business owners. Understand B2B and B2C reporting, exports, credit/debit notes, advances, amendments, HSN/SAC, documents issued, e-commerce supplies, GSTR-1A and the controls needed to reconcile books with the GST portal.

Table-wisePractical examplesB2B / B2C / ExportGSTR-1ABooks ↔ GSTR-1 ↔ 3BInternal GST references

1. What is GSTR-1 and why is it important?

GSTR-1 is the statement of outward supplies in which an eligible registered taxpayer reports the relevant sales and other outward-supply information for the applicable tax period.

Think of GSTR-1 as the detailed outward-supply data layer of GST compliance. It is not simply a sales summary. Depending on the transaction, it can contain invoice-level B2B information, specified B2C supplies, exports, SEZ supplies, credit and debit notes, advances, amendments, HSN/SAC summaries, documents issued and specified e-commerce related information.

This means a good GSTR-1 process should begin with the sales register and source documents, not with the GST portal. The portal is where the return is filed; the books and transaction documents are what establish the underlying working.

Golden rule: Close the sales data → classify every transaction → determine place of supply → validate GSTIN/customer status → prepare table-wise GSTR-1 → reconcile totals with books → review e-invoice/portal data → file → reconcile GSTR-1 with GSTR-3B.

For the underlying statutory provisions, use your GST Act — Section Wise Guide.

2. Who is required to file GSTR-1?

GSTR-1 is generally furnished by normal and casual registered taxpayers making outward supplies of goods or services or both, subject to the exclusions and special return mechanisms prescribed under GST.

Taxpayer / categoryGSTR-1 treatmentPractical point
Regular taxpayerGenerally files GSTR-1Monthly or quarterly frequency may apply.
Casual taxable personGenerally files the applicable outward-supply statementCheck the registration period and portal availability.
Composition taxpayerDoes not file normal GSTR-1Composition has its own compliance mechanism.
ISDDoes not use GSTR-1 for ISD distributionISD return mechanism applies.
TDS / TCS categoriesUse their prescribed returnsDo not assume every GSTIN files GSTR-1.
Important: Applicability should be tested against the taxpayer's registration status, nature of activity and the return framework applicable for the relevant period.

3. GSTR-1 due date and filing frequency

Filing frequencyGeneral GSTR-1 due datePractical explanation
Monthly11th of the succeeding monthExample: January GSTR-1 is generally due on 11 February.
Quarterly / QRMP13th of the month following the quarterExample: April–June quarterly GSTR-1 is generally due on 13 July.

These are the general timelines; the Government can extend dates for specified classes or periods. Always check the applicable notification and GST portal for the tax period concerned.

QRMP and Invoice Furnishing Facility

Eligible quarterly filers may use the Invoice Furnishing Facility (IFF) for the first two months of a quarter if they want to report specified B2B invoices and related documents earlier so that recipients can receive the corresponding information without waiting for the quarterly GSTR-1.

Do not confuse: IFF is an optional facility for eligible quarterly filers; it does not turn the taxpayer into a monthly GSTR-1 filer.

4. The practical GSTR-1 monthly / quarterly workflow

Freeze the sales register. Ensure invoices, debit notes, credit notes, exports, advances and amendments for the period are captured.
Classify every supply. Identify B2B, B2C, export, SEZ, deemed export, nil/exempt/non-GST and e-commerce categories as applicable.
Check GSTIN and customer status. A wrong GSTIN can move a transaction into the wrong reporting category and create recipient-side reconciliation problems.
Determine place of supply and tax type. Check whether IGST or CGST/SGST applies and whether the transaction is genuinely inter-State.
Prepare table-wise data. Do not upload everything into one generic sales bucket.
Reconcile e-invoice data. Compare IRP-generated information with the sales register and identify missing, cancelled or amended documents.
Review HSN/SAC and documents issued. Table 12 and Table 13 should be independently checked rather than completed at the last minute.
Generate and review GSTR-1 summary. Compare taxable value and tax totals with the approved books.
File GSTR-1 and preserve evidence. Save the filed return/ARN, final working and exception notes.
Reconcile with GSTR-3B. GSTR-1 outward liability should agree with the corresponding approved GSTR-3B working after considering timing and permitted differences.

5. Documents and data required before preparing GSTR-1

SourceWhat to extractWhy it matters
Sales registerInvoice number/date, customer GSTIN, taxable value, rate, tax, POS, document typePrimary source for outward-supply reporting.
Credit/debit note registerOriginal invoice reference, note number/date, taxable and tax adjustmentPrevents double reporting or missed adjustments.
Export documentationShipping bill / bill of export, recipient, port, tax treatment, invoice dataSupports export reporting and refund/LUT processes.
SEZ documentsRecipient status, endorsement/supporting documents and tax treatmentDetermines correct SEZ reporting.
E-invoice dataIRN, invoice number/date, recipient GSTIN, taxable value and taxIdentifies portal/source-data differences.
Advance registerAdvances received, tax treatment and later adjustmentImportant for applicable service transactions and adjustments.
HSN/SAC masterHSN/SAC, description, UQC, quantity, rate and valueSupports Table 12 accuracy.
Document series registerInvoices, credit notes, debit notes, cancelled documents and seriesSupports Table 13 completeness.

6. GSTR-1 table-wise map — understand the return before filing

Table / areaWhat it broadly capturesMain control
Basic detailsGSTIN, legal/trade name and tax periodConfirm correct GSTIN and period.
4A / 4B / 4C / 6B / 6CSpecified B2B supplies and related categoriesRecipient GSTIN, invoice and tax type.
5Specified B2C inter-State supplies, including the applicable threshold/category logicPOS, recipient status and invoice value/category.
6AExportsExport type, invoice and shipping/bill-of-export details.
6B / 6CSpecified SEZ supplies, depending on tax-payment treatmentSEZ status and tax treatment.
7Specified B2C other supplies / consolidated reportingState-wise and tax-rate classification.
8Nil-rated, exempt and non-GST outward suppliesDo not mix exempt with non-GST without checking classification.
9A / 9BSpecified amendments and credit/debit notes, including registered/unregistered categories as applicableOriginal document reference and correct period.
10Specified amendments to B2C detailsLink amended figure to original reporting.
11Advances received and their adjustment, where applicableTrack receipt and subsequent invoice/adjustment.
12HSN/SAC-wise summary of outward suppliesReconcile HSN summary to sales data.
13Documents issuedReconcile invoice/note series with books.
14 / 15Specified e-commerce operator / Section 9(5) related reporting introduced in the return structureCheck the applicable nature of supply and ECO role.
Table numbering can evolve: GST portal labels and functionality can change through notifications and portal updates. Use the table applicable to the relevant tax period rather than copying an old return format.

7. B2B reporting — the most important invoice-level area

A B2B supply is generally a supply to a registered recipient and is reported with invoice-level information. The recipient GSTIN becomes a critical field because the recipient may use the reported data for reconciliation and ITC-related processes.

FieldWhat to verifyCommon failure
Recipient GSTINCorrect GSTIN and active/valid status as relevant to the invoice dateOne digit wrong or old GSTIN used.
Invoice numberExactly matches source invoice and document seriesSlash, hyphen, zero or series difference.
Invoice dateCorrect date and tax periodInvoice posted in wrong month.
Taxable valueAgrees with invoice and booksDiscount/freight/rounding treated inconsistently.
Tax rateCorrect rate for supplyWrong rate creates recipient mismatch.
Tax typeIGST vs CGST/SGSTWrong POS causes wrong tax type.
Place of supplyCorrect State and applicable statutory ruleBilling State assumed to be POS without analysis.
Example — B2B invoice: A Telangana supplier invoices a Karnataka registered customer for ₹10,00,000 taxable value at 18%. Before filing, verify customer GSTIN, POS Karnataka, IGST ₹1,80,000, invoice number/date and whether the invoice has already been reported through e-invoice data.

8. B2C reporting — do not treat every consumer invoice the same

B2C reporting depends on whether the recipient is registered, whether the supply is inter-State or intra-State, the invoice value and the specific reporting rules applicable to the tax period.

B2C Large / specified inter-State category

Check whether the invoice falls within the applicable inter-State B2C reporting threshold/category. Such transactions may require invoice-level reporting.

B2C Other

Other specified consumer supplies are generally reported in the applicable consolidated/state-wise structure, subject to the return rules and portal format.

Practical control: Never decide B2C reporting solely from the customer name. Determine registration status, POS, supply value and applicable table logic.

9. Exports and SEZ supplies

TransactionWhat to verifyPractical risk
Export with payment of IGSTExport invoice, shipping/bill-of-export details, tax amount and return reportingInvoice/port details mismatch can affect refund processing.
Export under LUT/bondLUT/bond status and correct zero-rated reportingIncorrect tax treatment may create unnecessary liability or refund issues.
Supply to SEZ with paymentSEZ recipient status, endorsement/support and tax treatmentWrong classification may affect recipient/refund documentation.
Supply to SEZ without paymentEligibility for zero-rated treatment and supporting documentsMissing endorsement/support can become a documentation issue.
Example: A Hyderabad manufacturer exports goods under LUT. The sales register, export invoice, shipping bill and GSTR-1 should tell the same story. If the invoice is reported as a normal domestic B2B sale, the books may still balance while the GST reporting is wrong.

10. Credit notes and debit notes

Credit/debit note reporting needs a strong link between the original invoice, the adjustment document and the reason for adjustment. The note should not be treated as an independent sales transaction.

ControlQuestion
Original invoiceWhich original supply is being adjusted?
Note number/dateIs the document number unique and within the correct series?
Taxable valueDoes the adjustment agree with the accounting entry?
Tax amountIs the CGST/SGST/IGST adjustment correct?
Recipient categoryWas the original supply B2B, B2C or another category?
AmendmentIs the original GSTR-1 entry itself being amended?
Common error: Reporting a credit note without checking whether the original invoice was reported under the correct GSTIN, tax type and period can create a mismatch on both sides.

11. Advances received — when and how they affect GSTR-1

Advance reporting should be analysed according to the nature of supply and the applicable time-of-supply rules. The important practical point is to maintain a clear bridge between advance received → tax treatment → later invoice → adjustment.

Advance register → Applicable tax treatment → GSTR-1 advance reporting (where required) → Invoice issued → Advance adjusted → Reconciliation
Example: A service provider receives ₹5,00,000 advance in one period and raises the final invoice later. The accounting and GST working should track the advance, applicable tax treatment and eventual adjustment rather than reporting the invoice and advance independently as two taxable sales.

12. Amendments — how to correct an earlier GSTR-1 entry

GSTR-1 has amendment mechanisms for specified previously reported details. The correct amendment table depends on the nature of the original reporting and the type of correction.

Original errorTypical correction thought process
Wrong GSTINTrace original invoice, identify recipient impact and use the applicable amendment mechanism.
Wrong taxable value/taxCompare invoice, books and original GSTR-1 before amending.
Wrong POSReassess place of supply and tax type before making the amendment.
Invoice omittedDetermine whether it can be added through the same-period facility or subsequent permitted reporting.
Wrong invoice number/dateCorrect the original record using the appropriate amendment facility.
Best practice: Maintain a GSTR-1 amendment register containing original value, corrected value, reason, supporting document, period and reviewer approval.

13. Table 12 — HSN/SAC-wise summary

Table 12 is a frequent source of filing errors because it is often prepared after all invoice-level reporting is completed. It should instead be generated from the same controlled sales data used for the return.

GSTN has enhanced Table 12 so that HSN reporting is separated into B2B Supplies and B2C Supplies, with facilities such as an updated HSN/SAC list and searchable product master functionality. The applicable HSN digit requirement depends on the prescribed turnover/category rules.

CheckWhat to reconcile
HSN/SACCorrect code for the goods/services supplied.
DescriptionConsistent product/service description.
UQCCorrect unit for goods where quantity reporting applies.
QuantityAgree with source sales data where required.
Taxable valueAggregate by HSN/SAC and reconcile to outward supply data.
RateDo not combine incompatible rates into a single line.
TaxIGST/CGST/SGST totals should reconcile with the relevant sales working.
2025 portal enhancement: GSTN advised that Table 12 is bifurcated into B2B and B2C tabs and that a “Download HSN Codes List” facility is available. Use the current portal functionality rather than an old offline template.

14. Table 13 — Documents issued

Table 13 is not a decorative table. It is a control bridge between the document series maintained by the business and the documents reported through GST compliance.

GSTN made reporting in Table 13 mandatory from the May 2025 return period where the relevant conditions apply. Where B2B/B2C supplies are reported, the portal requires the applicable document details to be completed before filing.

DocumentReconciliation
InvoicesOpening series + additions − cancellations should reconcile with closing series / actual documents.
Credit notesSerial series should agree with the note register.
Debit notesSerial series should agree with the note register.
Cancelled documentsCancellation should be supported by the document register.
Control example: If the ERP shows invoice numbers 1001–1100 and 5 cancellations, the finance team should be able to explain the 100 issued/active documents and the cancelled series before filing Table 13.

15. E-commerce and Section 9(5) related reporting

The GSTR-1 structure includes reporting for specified supplies involving electronic commerce operators and supplies covered by the Section 9(5) mechanism. The exact reporting depends on the taxpayer's role and the nature of the supply.

QuestionControl
Is the taxpayer the supplier or ECO?Identify the legal role before selecting the table.
Does Section 9(5) apply?Check the notified categories and current provisions.
Who is liable to pay GST?Do not assume the supplier and ECO always have the same liability.
Is the same transaction already reported elsewhere?Check for duplicate reporting.
Common mistake: Treating every online sale as a Section 9(5) transaction. The mechanism applies only to specified categories covered by the law.

16. GSTR-1A — the same-period correction opportunity

GSTR-1A is an important addition to the practical GSTR-1 workflow. It provides an optional facility to amend or add specified records for the same tax period after GSTR-1 has been filed and before the corresponding GSTR-3B is filed, subject to the portal and applicable rules.

QuestionPractical answer
Is GSTR-1A compulsory?No. It is an optional correction facility.
When is it available?For monthly filers, from the later of the GSTR-1 due date or actual GSTR-1 filing date until GSTR-3B filing for the same period. Quarterly filers have the corresponding quarterly framework.
Can it be filed after GSTR-3B?No, the same-period GSTR-1A facility is not available after GSTR-3B is filed.
Does it replace later amendments?No. The normal permitted amendment mechanisms for earlier periods continue separately.
Example: A monthly taxpayer files GSTR-1 and later notices that one B2B invoice was omitted. If GSTR-3B for that period has not yet been filed and the GSTR-1A facility is available, the taxpayer can evaluate whether the omission can be corrected through GSTR-1A rather than carrying the error forward.

17. E-invoice and GSTR-1 auto-population

For taxpayers covered by e-invoicing, invoice details generated through the Invoice Registration Portal can flow into specified GSTR-1 tables. This can reduce manual entry, but it does not remove the need for reconciliation.

SourceControl question
ERP sales registerWas the invoice actually accounted for?
IRP / e-invoice dataWas IRN generated, cancelled or amended?
GSTR-1 auto-populationDid the invoice appear in the expected table?
Final GSTR-1Does the filed return agree with the approved sales register?
Important: Auto-population is not a substitute for review. An incorrect source invoice can simply create an incorrect auto-populated return entry.

18. Common GSTR-1 mistakes and their impact

Wrong entryPossible impactControl
Wrong customer GSTINRecipient mismatch and possible ITC/reconciliation issues.Validate GSTIN before upload.
Wrong POSWrong IGST vs CGST/SGST and state reporting.Independent POS review.
Invoice omittedOutward liability and recipient data may be understated.Sales register ↔ GSTR-1 reconciliation.
Duplicate invoiceOverstatement of turnover/tax and recipient mismatch.Invoice-number duplicate check.
Wrong tax rateTax difference and recipient mismatch.Rate master + invoice review.
Credit note missedTurnover/tax overstated.Credit note register reconciliation.
Wrong B2B/B2C classificationIncorrect table and customer reporting.GSTIN/status based classification.
Export reported as domesticRefund/zero-rated compliance issues.Export document reconciliation.
HSN mismatchTable 12 mismatch and compliance risk.HSN master and summary reconciliation.
Table 13 incompletePortal filing validation issue.Document-series control.
E-invoice not reconciledMissing or duplicate portal data.ERP ↔ IRP ↔ GSTR-1 reconciliation.
GSTR-1 filed but 3B not reconciledTax liability difference may remain undetected.Mandatory post-filing bridge.

19. What happens if GSTR-1 contains a wrong figure?

The correction route depends on the nature of the error, whether GSTR-1 is filed, whether GSTR-3B has been filed, the relevant tax period and the specific amendment mechanism available.

SituationPractical approach
Before filing GSTR-1Correct the source working and portal entry before final submission.
GSTR-1 filed, GSTR-3B not filedEvaluate GSTR-1A where available and appropriate.
GSTR-3B already filedUse the permitted subsequent-period amendment/correction mechanism and assess tax/interest consequences.
Wrong GSTINCorrect the recipient reporting and reconcile the recipient impact.
Understated taxQuantify short-payment, determine interest and complete the permitted correction/payment process.
Overstated taxDetermine the permitted correction/refund/adjustment route based on the facts.
Never simply overwrite the accounting records. Keep an amendment register showing the original entry, corrected entry, reason, document evidence, return period and approval.

20. Practical GSTR-1 examples across industries

Construction / infrastructure: A contractor raises running account bills to a registered project owner. The finance team should reconcile RA bill, tax invoice, GSTIN, POS, retention/other deductions, debit/credit notes and GSTR-1 before the return is filed.
Manufacturing: A factory has hundreds of B2B invoices and e-invoices. The safest workflow is ERP sales register → IRP data → GSTR-1 B2B → HSN summary → GSTR-3B liability.
IT / software services: A service provider invoices customers in several States and overseas. Place of supply, export/zero-rated classification, customer GSTIN and invoice period should be separately reviewed.
Real estate: Customer advances, later invoices and credit notes can create timing differences. Maintain an advance-to-invoice bridge rather than relying only on the ledger closing balance.
Hospitality: A hotel may have registered corporate customers, consumers, exports/SEZ-type cases in limited situations and e-commerce channels. Customer status and POS should drive classification.
E-commerce seller: Separate ordinary outward supplies from transactions where a specific ECO/Section 9(5) mechanism applies. Do not classify every marketplace sale under Section 9(5).

21. Internal controls for a professional GSTR-1 process

ControlResponsible activityEvidence
Sales completenessAccounts compares ERP sales ledger with invoice register.Sales reconciliation.
GSTIN validationPreparer validates customer GSTIN/status.Validation report / master approval.
POS reviewReviewer checks inter-State vs intra-State classification.Exception report.
E-invoice reconciliationAccounts compares ERP invoices with IRP records.IRN reconciliation.
Credit/debit notesAccounts reconciles note register with GSTR-1.Note reconciliation.
HSN reviewReviewer checks Table 12 totals and code mapping.HSN summary working.
Document seriesAccounts reconciles Table 13 with document register.Series reconciliation.
GSTR-1 reviewPreparer enters; reviewer verifies; authorised signatory files.Pre-filing checklist.
GSTR-1 vs 3BTax team reconciles outward tax after filing.Return-to-return bridge.

22. Final GSTR-1 filing checklist

  • Sales register is complete and period is frozen.
  • All invoice series are accounted for.
  • Customer GSTINs are validated.
  • B2B/B2C classification is reviewed.
  • Place of supply and tax type are checked.
  • Exports and SEZ supplies are reconciled with supporting documents.
  • Credit/debit notes are reconciled.
  • Advances and adjustments are reviewed where applicable.
  • Amendments are linked to original reporting.
  • Table 12 HSN/SAC summary agrees with outward supplies.
  • Table 13 documents issued agrees with document registers.
  • Section 9(5)/ECO reporting is separately checked where applicable.
  • E-invoice data is reconciled with ERP and GSTR-1.
  • GSTR-1 summary agrees with the approved sales working.
  • GSTR-1A opportunity is considered before filing GSTR-3B if an error is identified.
  • Filed return, ARN and final working papers are preserved.
  • GSTR-1 is reconciled with GSTR-3B after filing.

23. GST legal and practical references

This article uses GST Reconciliation as the primary explanatory reference library. The purpose is to connect each concept to the site's GST Act section-wise material instead of sending readers to a different explanatory website for every basic provision.

TopicInternal referenceStatus
CGST Act section-wise provisionsGST Act — Section Wise GuideAvailable
GSTR-2B reconciliationGSTR-2B Reconciliation GuideAvailable / verify URL
GSTR-3B returnGSTR-3B Practical GuideAvailable
GST compliance workflowGST Compliance CentreAvailable
GSTR-1 / GSTR-1AThis articleCurrent guide

Core legal areas to understand

Provision / areaWhy it matters to GSTR-1
Section 37Core statutory provision for furnishing outward-supply details.
Section 31Invoice and document timing/content affects the source data reported.
Section 10 / special taxpayer provisionsHelps determine whether the normal GSTR-1 framework applies.
Section 12 / 13Time-of-supply analysis can determine the period in which a transaction belongs.
Section 15Taxable value affects the amounts reported.
IGST Act place-of-supply provisionsCritical for IGST vs CGST/SGST and export/inter-State reporting.
Rule 59Form and manner of furnishing outward-supply details and related filing restrictions.
Recommended website architecture: Article → GST Act Section → Rule → Notification / Advisory → Table-wise explanation → Practical example → Reconciliation control. This turns the website into a connected GST knowledge base rather than a collection of isolated articles.

Related GST return filing resources

Continue with the GSTR-1 & GSTR-1A practical guide, the GSTR-3B Return Filing Guide, the GSTR-2B Reconciliation Guide and the GST Compliance Centre.

Quick reference: GSTR-1 in one view

AreaMain question
B2BIs the recipient GSTIN, invoice and tax classification correct?
B2CIs the consumer transaction in the correct reporting category and State/POS?
Exports / SEZIs the zero-rated / SEZ treatment supported by the underlying documents?
NotesIs every credit/debit note linked to the correct original supply?
AdvancesHas the applicable advance and later adjustment been tracked?
AmendmentsCan every change be traced to the original GSTR-1 entry?
HSNDoes Table 12 reconcile with the outward supply register?
DocumentsDoes Table 13 reconcile with invoice/note series?
ECO / 9(5)Does the transaction actually fall within the specified mechanism?
GSTR-1AWas any same-period error identified before GSTR-3B filing?
GSTR-3BDoes the final outward tax reconcile with the return liability?

24. Frequently asked questions about GSTR-1

What is GSTR-1?

GSTR-1 is the statement of outward supplies furnished by eligible registered taxpayers for the applicable tax period.

Is GSTR-1 a tax payment return?

GSTR-1 is primarily the statement of outward supplies. The actual summary liability and payment process is dealt with through the applicable return, including GSTR-3B for normal taxpayers.

What is the general due date of GSTR-1?

The general due date is the 11th of the succeeding month for monthly filers and the 13th of the month following the quarter for quarterly filers, subject to notifications or extensions.

Can quarterly filers use IFF?

Eligible QRMP taxpayers may use IFF for specified supplies in the first two months of a quarter. It is an optional facility.

What is GSTR-1A?

GSTR-1A is an optional same-period amendment/addition facility available after GSTR-1 and before filing GSTR-3B for the same tax period, subject to the applicable portal framework.

Can GSTR-1A be filed after GSTR-3B?

No. The same-period GSTR-1A facility is not available after GSTR-3B for that period has been filed.

Is Table 13 mandatory?

GSTN made Table 13, documents issued, mandatory from the May 2025 return period where applicable. The portal can validate the table before filing.

Does GSTR-1 contain purchase ITC?

No. GSTR-1 is an outward-supply statement. Purchase-side ITC is dealt with through the relevant ITC and return processes.

Does e-invoice automatically make GSTR-1 correct?

No. E-invoice data can auto-populate specified GSTR-1 tables, but the taxpayer should reconcile ERP, IRP and final GSTR-1 data.

What are the most common GSTR-1 mistakes?

Common failures include wrong GSTIN, wrong POS, duplicate invoices, omitted invoices, wrong tax rate, incorrect B2B/B2C classification, missed credit notes, incorrect export/SEZ treatment, HSN errors and incomplete document-series reporting.

How should GSTR-1 be reconciled with GSTR-3B?

Compare taxable turnover and tax liability category-wise, investigate timing differences, amendments and notes, and ensure the final outward liability in GSTR-3B is supported by the approved GSTR-1 working.

Disclaimer: This guide is for educational and practical working purposes. GST law, rules, notifications, circulars, advisories, return forms and portal functionality can change. Apply the law and procedure relevant to the specific tax period, transaction and taxpayer category.