Indian businesses registered under GST should keep track of the September 2026 return-filing calendar to avoid missing statutory deadlines, late fees and other compliance issues.
For businesses filing GST returns on a monthly basis, the August 2026 tax-period compliance cycle includes important deadlines during September. GSTR-1 for August 2026 was due on 11 September 2026, while GSTR-3B for August 2026 is generally due on 20 September 2026 for monthly filers.
For eligible taxpayers following the QRMP scheme, filing dates can differ depending on the applicable return and state or Union Territory.
The exact applicability of each return depends on the taxpayer's registration status, turnover, filing frequency and nature of business.
GSTR-1: Reporting Outward Supplies
GSTR-1 is used by registered taxpayers to report details of their outward supplies of goods and services.
For monthly filers, the GSTR-1 for August 2026 was due on 11 September 2026. Businesses should ensure that their sales invoices, credit notes, debit notes and other relevant outward-supply information are properly recorded and reconciled before filing.
If you have not yet completed your GST return compliance for the relevant period, professional assistance can help ensure that the applicable returns and supporting information are reviewed before submission.
Related service: GST Return Filing
GSTR-3B: Summary Return and Tax Payment
GSTR-3B is a summary GST return through which eligible taxpayers declare their tax liabilities and discharge the applicable tax payment.
For monthly filers, the GSTR-3B for August 2026 is generally due on 20 September 2026.
Businesses should review their outward supplies, eligible input tax credit, tax liability and other relevant records before filing the return.
Incorrect or incomplete reporting can create reconciliation issues later, making timely review an important part of GST compliance.
Related service: GST Return Filing
QRMP Taxpayers Should Check Their Applicable Dates
Businesses eligible for and enrolled under the Quarterly Return Monthly Payment (QRMP) scheme follow a different compliance cycle from regular monthly filers.
For taxpayers covered under the QRMP mechanism, monthly tax payments and quarterly return requirements may apply depending on the taxpayer's circumstances.
In Maharashtra and several other states, the September 2026 compliance calendar includes a 22 September due date for the quarterly GSTR-3B for eligible taxpayers covered by the applicable QRMP category.
Businesses should therefore verify their filing frequency rather than relying on a single GST deadline.
What Businesses Should Check Before Filing GST Returns
Before filing a GST return, businesses should review:
Sales and purchase records
Tax invoices and credit/debit notes
Output GST liability
Eligible Input Tax Credit (ITC)
GST portal data and reconciliation
Previous-period adjustments
Tax payment requirements
Pending returns, if any
Any GST notices or communications received on the portal
Maintaining accurate records and completing reconciliation before filing can reduce the possibility of avoidable errors.
What Happens If GST Returns Are Delayed?
Missing a GST filing deadline may result in applicable late fees and interest depending on the type of return, tax liability and circumstances.
Businesses with pending returns should review their GST compliance position and determine which returns are outstanding and what liabilities may apply before proceeding with filing.
GST Compliance Is an Ongoing Responsibility
GST compliance is not limited to filing a return once a month or quarter. Businesses need to maintain proper invoices, reconcile transactions, monitor Input Tax Credit, track applicable deadlines and respond appropriately to GST communications.
Regular compliance review can help businesses avoid last-minute filing pressure and identify discrepancies earlier.
If your business requires assistance with regular GST compliance, return filing or related GST requirements, professional support can help streamline the process.
VyaparDoot provides GST-related professional services including GST Registration, GST Return Filing, NIL GST Return Filing, GST Annual Return, GST Amendment & Revocation and GST Notice Reply services.
Explore our GST Return Filing service or contact VyaparDoot at +91 7035235235 for assistance with your business compliance requirements.
Important Note
GST due dates can vary depending on the taxpayer category, turnover, filing frequency, location and applicable government notifications. Businesses should verify the applicable deadline on the official GST portal before filing.