GST Filing Guide for Business Owners FY 2025-26

GST filing in FY 2025-26 requires more than submitting GSTR-1 and GSTR-3B on time. Business owners must also reconcile GSTR-2B, report invoices correctly, claim eligible input tax credit (ITC), follow e-invoicing rules and complete the annual return where applicable.

This guide explains GST filing by a business owner in AY 2026-27. Technically, GST follows the financial year, so the more accurate reference is GST filing for FY 2025-26. The key compliance year runs from 1 April 2025 to 31 March 2026, with several returns and annual compliance activities continuing into FY 2026-27.

GST return filing due dates FY 2025-26

The return due date depends on your filing frequency, turnover, State or Union Territory and whether you use the QRMP scheme.

GST compliance	Monthly filer	Quarterly filer under QRMP
GSTR-1	11th of the following month	13th after the quarter
GSTR-3B	20th of the following month	22nd or 24th after the quarter
PMT-06 challan	25th of the following month for the first two months of a quarter	Applicable under the quarterly payment option
GSTR-9 annual return	31 December after the financial year	31 December after the financial year, if applicable
GSTR-9C reconciliation statement	31 December after the financial year, if applicable	31 December after the financial year, if applicable

The government may extend a due date through a notification. Business owners should therefore verify the return period and due date on the official GST portal before filing.

Monthly GSTR-1 due dates

A regular monthly taxpayer generally files GSTR-1 by the 11th of the succeeding month.

Examples:

• April 2025 GSTR-1: 11 May 2025
• May 2025 GSTR-1: 11 June 2025
• March 2026 GSTR-1: 11 April 2026

GSTR-1 reports outward supplies, including taxable sales, exports, credit notes, debit notes and certain amendments.

Monthly GSTR-3B due date

A monthly filer generally submits GSTR-3B by the 20th of the succeeding month.

Examples:

• April 2025 GSTR-3B: 20 May 2025
• February 2026 GSTR-3B: 20 March 2026
• March 2026 GSTR-3B: 20 April 2026

GSTR-3B is a summary return in which the taxpayer declares outward tax liability, eligible ITC, reverse charge liability and the net tax payable.

GST quarterly return filing under the QRMP scheme

The Quarterly Return Monthly Payment, or QRMP, scheme allows eligible taxpayers to file GSTR-1 and GSTR-3B quarterly while paying tax every month.

The scheme is generally available to taxpayers with aggregate annual turnover of up to ₹5 crore, subject to the applicable conditions and portal eligibility.

How QRMP works

For each quarter:

1. Pay the tax for the first two months through a PMT-06 challan.
2. File GSTR-1 quarterly by the 13th of the month following the quarter.
3. File quarterly GSTR-3B by the 22nd or 24th, depending on the State or Union Territory.
4. Pay the balance tax while filing the quarterly GSTR-3B.

For the first two months, the taxpayer may use either of these payment methods:

• Fixed sum method: Pay the prescribed percentage of the tax paid in the previous quarter.
• Self-assessment method: Calculate the actual tax liability for the month and pay it.

The fixed sum method reduces monthly calculation work, while the self-assessment method may be useful when sales vary significantly.

Invoice Furnishing Facility under QRMP

QRMP taxpayers can use the Invoice Furnishing Facility, or IFF, to upload selected B2B invoices for the first two months of a quarter. IFF is optional, but it helps customers view invoices in their auto-generated records earlier and claim ITC more efficiently.

IFF generally closes on the 13th of the month following the relevant month. A taxpayer should use it when important B2B customers need invoice visibility before the quarterly GSTR-1 is filed.

GSTR-1 filing guide for small businesses

GSTR-1 must accurately match the business's sales register and tax invoices. Incorrect outward supply reporting can create mismatches for customers and may lead to follow-up notices.

Information generally reported in GSTR-1

A business owner may need to report:

• Business-to-business, or B2B, invoices
• Business-to-consumer large-value invoices
• Export invoices
• Supplies to SEZ units or developers
• Credit notes and debit notes
• Advances received in relevant cases
• Amendments to previously reported invoices
• HSN or SAC-wise summary of outward supplies
• E-commerce operator-related supplies, wherever applicable

GSTR-1 filing process

Before filing:

1. Download the sales register for the return period.
2. Separate B2B, B2C, export, SEZ and exempt supplies.
3. Verify each customer's GSTIN from reliable records.
4. Check invoice numbers, dates, taxable values and tax rates.
5. Report credit notes and debit notes in the correct period.
6. Validate HSN or SAC codes and unit details.
7. Compare the GSTR-1 summary with the books and e-invoice data.
8. File using a digital signature or electronic verification code, as applicable.

A common error is reporting a B2B invoice as B2C. This prevents the recipient from seeing the invoice correctly in its inward supply records and can delay ITC reconciliation.

GSTR-3B filing guide for business owners

GSTR-3B should be prepared only after reconciling the books, GSTR-1 and available GSTR-2B. It is not a substitute for the detailed sales and purchase records maintained by the business.

Key sections in GSTR-3B

A taxpayer generally reports:

• Taxable outward supplies
• Zero-rated supplies
• Nil-rated and exempt supplies
• Supplies liable to reverse charge
• Inward supplies from an e-commerce operator, where applicable
• Eligible ITC
• ITC reversals
• Interest and late fee
• Tax paid through the electronic cash and credit ledgers

Practical GSTR-3B workflow

Use this monthly checklist:

1. Reconcile sales in the books with GSTR-1.
2. Confirm that the tax liability in GSTR-3B agrees with GSTR-1.
3. Download and review GSTR-2B.
4. Remove ineligible, blocked or unsupported ITC.
5. Record reverse charge purchases separately.
6. Calculate ITC reversals for exempt supplies and non-business use, where applicable.
7. Pay tax through the electronic cash ledger and electronic credit ledger.
8. File GSTR-3B by the applicable due date.

Do not claim ITC merely because an invoice is present in your purchase register. The claim should satisfy the conditions under the GST law, including receipt of goods or services, possession of a tax invoice, payment of tax to the government by the supplier where applicable, and filing within the statutory time limit.

GST input tax credit reconciliation with GSTR-2B

GSTR-2B is a read-only, static statement generated for a particular period. It reflects eligible and ineligible ITC based mainly on supplier filings and other data available to the GST system.

The recipient should reconcile GSTR-2B with:

• Purchase register
• Tax invoices
• Goods receipt notes
• Expense ledger
• Supplier GSTIN
• GSTR-3B ITC claim
• Credit notes and debit notes
• Reverse charge records

What to do with mismatches

Mismatch	Recommended action
Invoice in books but absent from GSTR-2B	Contact supplier and request correct reporting
Invoice in GSTR-2B but absent from books	Investigate before claiming ITC
Wrong GSTIN	Ask supplier to amend the invoice
Incorrect tax amount	Reconcile with the invoice and request correction
Duplicate invoice	Remove the duplicate claim
Credit note not recorded	Adjust ITC and purchase accounting
ITC marked ineligible	Do not claim until eligibility is established

For FY 2025-26, taxpayers should track the statutory time limit for claiming missed ITC. Under the applicable rule for the relevant period, a missed invoice or debit note generally cannot be claimed after 30 November 2026 or the date of filing the relevant annual return, whichever is earlier, subject to specific legal provisions and notified exceptions. The Central Goods and Services Tax Act contains the core statutory framework.

Example of ITC reconciliation

A manufacturer records a purchase invoice of ₹1,00,000 plus ₹18,000 GST in August 2025. The invoice does not appear in GSTR-2B for the relevant period.

The business should:

1. Check whether the supplier uploaded the invoice in a later period.
2. Confirm that the GSTIN and invoice number are correct.
3. Ask the supplier to file or amend the invoice.
4. Claim ITC only after verifying eligibility and the applicable time limit.
5. Maintain written reconciliation evidence.

GST invoice reporting requirements FY 2025-26

A GST tax invoice should contain the prescribed particulars, including:

• Supplier's legal name, address and GSTIN
• Unique invoice number
• Invoice date
• Customer details and GSTIN, where applicable
• Place of supply
• HSN or SAC code
• Description and quantity of goods or services
• Taxable value
• CGST, SGST, IGST or UTGST rate and amount
• Whether reverse charge applies
• Signature or authorised electronic authentication

E-invoicing requirements

E-invoicing applies to notified taxpayers crossing the prescribed aggregate turnover threshold. During FY 2025-26, the general applicability threshold remained ₹5 crore aggregate turnover, subject to the notified rules and exclusions.

A covered taxpayer must generate an Invoice Reference Number, or IRN, through the Invoice Registration Portal for applicable B2B and other notified transactions. The taxpayer should not treat an ordinary PDF invoice as a replacement for a required e-invoice.

From 1 April 2025, taxpayers with aggregate annual turnover of ₹10 crore or more became subject to the requirement to report e-invoices within 30 days from the invoice date, according to the GSTN advisory. Businesses in this category should build an internal approval process so that invoices do not remain unreported beyond the permitted period. Check the latest GSTN advisories for portal instructions and updates.

E-invoice control points

Before issuing an invoice, verify:

• Correct recipient GSTIN
• Correct place of supply
• Applicable tax rate
• HSN or SAC code
• Document type
• Invoice date
• Whether the transaction requires an IRN
• Whether the invoice is reported within the applicable time limit

Cancel an incorrect e-invoice within the permitted period and issue a fresh document where required. Do not make accounting adjustments without updating the corresponding GST document trail.

GST late fee and interest calculation

Late filing can result in both late fee and interest. The amount depends on the return, tax liability and notified relief.

Interest on delayed tax payment

Interest is generally calculated on the delayed tax payable at the applicable statutory rate, commonly 18% per annum for delayed payment of tax. The calculation is:

Interest = Tax payable × 18% × Number of days of delay ÷ 365

Example:

• Tax payable: ₹1,00,000
• Delay: 10 days
• Interest: ₹1,00,000 × 18% × 10 ÷ 365
• Approximate interest: ₹493

Interest may apply differently where a taxpayer wrongly or excessively claims and utilises ITC. Such cases can attract the higher rate prescribed under the GST law.

Late fee

For delayed filing of regular returns such as GSTR-1 and GSTR-3B, the usual late fee is calculated separately under the Central GST and State or Union Territory GST components. The commonly applicable aggregate rate is:

• ₹50 per day for a taxable return
• ₹20 per day where there is no tax liability, subject to the applicable cap and notified relief

The maximum late fee can vary by return type and notification. Before payment, review the amount generated on the GST portal and check any applicable government notification.

Late fee does not replace the tax and interest liability. A taxpayer must pay all applicable amounts before or along with filing the delayed return.

GSTR-9 annual return filing FY 2025-26

GSTR-9 is the annual return that consolidates the taxpayer's GST activity for a financial year. It brings together outward supplies, inward supplies, ITC, tax paid, amendments and other annual information.

For FY 2025-26, the normal due date for an applicable taxpayer is 31 December 2026, unless the government extends it.

Who should prepare for GSTR-9?

A business should prepare annual return data if it has:

• Filed regular GSTR-1 and GSTR-3B during the year
• Made taxable, exempt, nil-rated or zero-rated supplies
• Claimed ITC
• Issued credit notes or debit notes
• Had reverse charge transactions
• Made amendments after the original reporting period

The government may exempt specified taxpayers below a prescribed turnover threshold from GSTR-9 for a particular financial year. Therefore, confirm the applicable notification for FY 2025-26 before concluding that the annual return is not required.

GSTR-9 preparation checklist

Reconcile these figures before filing:

1. Turnover in financial statements with GSTR-1.
2. GSTR-1 liability with GSTR-3B tax payment.
3. Purchase register with GSTR-2B.
4. ITC claimed with eligible ITC in the books.
5. Reverse charge liability with payment records.
6. Credit notes and debit notes with annual turnover.
7. Export and SEZ supplies with supporting documents.
8. Tax paid through cash and credit ledgers.
9. Amendments reported in later periods.
10. Differences requiring additional tax payment.

If the aggregate annual turnover exceeds the prescribed threshold, the taxpayer may also need a self-certified GSTR-9C reconciliation statement. For applicable taxpayers, the commonly relevant threshold is ₹5 crore, subject to the law and notifications for the financial year.

GST compliance checklist for Indian businesses

Use this recurring checklist throughout FY 2025-26 and while completing annual compliance:

Daily or transaction-level controls

• Issue invoices with the correct GST particulars.
• Verify customer GSTIN and place of supply.
• Generate e-invoices and e-way bills where required.
• Record credit notes and debit notes promptly.
• Preserve purchase invoices and proof of receipt.

Monthly controls

• Reconcile sales with GSTR-1.
• Reconcile purchases with GSTR-2B.
• Review reverse charge transactions.
• Check blocked or ineligible ITC.
• Calculate ITC reversals where required.
• Verify electronic cash and credit ledger balances.
• File GSTR-1 and GSTR-3B by the due date.

Quarterly QRMP controls

• Pay PMT-06 for the first two months.
• Decide whether to use IFF.
• Upload important B2B invoices through IFF, if useful.
• File quarterly GSTR-1.
• File quarterly GSTR-3B and pay the balance tax.

Annual controls

• Reconcile GST turnover with books and financial statements.
• Review all amendments made during the year.
• Check unclaimed ITC and the statutory deadline.
• Prepare GSTR-9 data.
• Determine whether GSTR-9C applies.
• Preserve workpapers and reconciliation records.

Common GST filing questions from business owners

Is GST filing required if there are no sales?

A registered taxpayer generally must file the applicable return even when there are no sales. A nil return may be filed where there are no outward supplies, inward supplies liable to reverse charge, ITC claims or other reportable activity.

Can I revise GSTR-1 or GSTR-3B?

GST returns generally do not have a simple revise-return facility. Errors are usually corrected in a subsequent return within the permitted time limits. The taxpayer should maintain a clear amendment trail and avoid duplicating an invoice.

Can a business claim ITC if the supplier has not filed GSTR-1?

The recipient should not claim ITC without checking the applicable statutory conditions and the invoice's appearance in the relevant system-generated statement. The practical approach is to follow up with the supplier, reconcile GSTR-2B and retain evidence supporting the claim.

What happens if GSTR-1 and GSTR-3B do not match?

A mismatch may generate an electronic communication, demand for clarification or scrutiny risk. The business should reconcile the difference, identify whether it relates to amendments, credit notes, timing or classification, and pay any shortfall with applicable interest.

Should a small business choose monthly filing or QRMP?

QRMP can reduce filing frequency for eligible businesses with moderate and stable transaction volumes. Monthly filing may be preferable when customers need faster invoice reflection, the business has frequent B2B sales or monthly reconciliation provides better control.

Final summary

For GST filing by a business owner in AY 2026-27, focus on the underlying FY 2025-26 records: file GSTR-1 and GSTR-3B on time, reconcile ITC with GSTR-2B, report e-invoices within the applicable period, monitor GST late fee and interest, and prepare GSTR-9 or GSTR-9C where required. A documented GST compliance checklist for Indian businesses helps prevent invoice mismatches, ITC disputes and avoidable late-payment costs. For GST filing for business owners FY 2025-26, use the official GST portal and current GSTN notifications to confirm due dates before submitting every return.