September 2026 Compliance Calendar: Important GST, Tax, ROC, PF & ESI Due Dates
September is an important compliance month for businesses, companies, startups, employers and taxpayers in India. Several GST returns, TDS payments, advance tax instalments, payroll-related compliances, ROC filings and tax audit requirements fall due during the month.
Missing a statutory deadline can result in interest, late fees, additional filing costs and, in some cases, other consequences. A well-maintained compliance calendar for September 2026 helps businesses track their obligations in advance instead of dealing with last-minute filings.
Below is a practical overview of the major September 2026 compliance deadlines.
Important: Due dates can be extended or modified through government notifications. State-specific compliances, including Professional Tax, may also have different deadlines. Businesses should verify the applicable date before making a filing or payment.
September 2026 Compliance Calendar at a Glance
| Due Date |
Compliance |
Period / Financial Year |
| 7 September 2026 |
TDS / TCS Payment |
August 2026 |
| 10 September 2026 |
Professional Tax on Salaries |
August 2026 |
| 11 September 2026 |
GSTR-1 – Monthly |
August 2026 |
| 13 September 2026 |
GSTR-1 IFF – Optional for QRMP |
August 2026 |
| 15 September 2026 |
Advance Tax – 2nd Instalment |
FY 2026-27 |
| 15 September 2026 |
PF & ESI Compliance / Payment |
August 2026 |
| 20 September 2026 |
GSTR-3B – Monthly |
August 2026 |
| 25 September 2026 |
GST PMT-06 Challan – QRMP |
August 2026 |
| 27 September 2026 |
AOC-4 – OPC |
FY 2025-26 |
| 30 September 2026 |
Annual General Meeting |
Applicable Companies |
| 30 September 2026 |
Tax Audit Report |
FY 2025-26 |
| 30 September 2026 |
Specified TDS Challan-cum-Statement Compliance |
August 2026 |
1. TDS / TCS Payment – 7 September 2026
Businesses and other deductors required to deposit TDS generally need to deposit tax deducted during August 2026 by 7 September 2026, subject to the applicable rules and exceptions.
TDS compliance is particularly important for businesses making payments such as:
- Salary
- Professional fees
- Contractor payments
- Rent
- Commission
- Interest
- Other specified payments
Businesses should reconcile their TDS deductions with their books of accounts and ensure that the correct amount is deposited on time.
2. Professional Tax on Salaries – 10 September 2026
Employers covered under applicable Professional Tax (PT) laws should deposit the professional tax deducted from employees' salaries for August 2026.
However, Professional Tax is a state-specific compliance. The applicable rate, registration requirement, return requirement and due date can differ from one state to another.
Therefore, businesses should not blindly apply 10 September as a universal Professional Tax deadline. The applicable state legislation and registration conditions should be checked before filing or payment.
3. GSTR-1 – 11 September 2026
Monthly GST taxpayers generally need to file GSTR-1 for August 2026 by 11 September 2026.
GSTR-1 contains details of outward supplies, including relevant:
- Business-to-business transactions
- Business-to-consumer supplies
- Credit and debit notes
- Export supplies
- Other applicable outward supply information
Why GSTR-1 Reconciliation Matters
Before filing GSTR-1, businesses should reconcile:
- Sales invoices
- Credit notes
- Debit notes
- Customer GSTINs
- Taxable values
- GST rates
- HSN/SAC details
- Export transactions
Errors in GSTR-1 can affect the recipient's input tax credit and may create unnecessary reconciliation issues.
4. GSTR-1 IFF for QRMP Taxpayers – 13 September 2026
Eligible taxpayers using the QRMP (Quarterly Return Monthly Payment) Scheme may use the Invoice Furnishing Facility (IFF) for the relevant month.
For August 2026, the IFF deadline is 13 September 2026, where applicable.
IFF is particularly useful for QRMP taxpayers who want to make eligible invoice details available to recipients during the quarter rather than waiting for the quarterly GSTR-1 filing.
5. Advance Tax – 15 September 2026
15 September 2026 is an important income-tax deadline because it marks the second advance-tax instalment for FY 2026-27.
Eligible taxpayers generally need to pay advance tax when their estimated tax liability meets the prescribed threshold after considering applicable credits such as TDS.
The second instalment falls due on 15 September and brings cumulative advance-tax payment to the prescribed 45% level.
Advance tax may be relevant for:
- Companies
- LLPs
- Firms
- Professionals
- Business owners
- Individuals with significant non-salary income
- Taxpayers earning income from multiple sources
Taxpayers should estimate their income and tax liability instead of waiting until the end of the financial year.
6. PF & ESI Compliance – 15 September 2026
Employers covered under applicable Provident Fund (PF) and Employee State Insurance (ESI) requirements need to complete their monthly payroll-related compliance for August 2026.
PF contributions are generally required to be remitted by the 15th of the following month.
Employers should ensure that employee deductions, employer contributions, wage records and payment records are properly reconciled.
For ESI, employers should also check the applicable statutory payment timeline and current ESIC requirements before filing or paying.
7. GSTR-3B – 20 September 2026
Monthly GST taxpayers generally need to file GSTR-3B for August 2026 by 20 September 2026.
GSTR-3B is a summary GST return used to declare GST liabilities and discharge the applicable tax liability.
Before filing, businesses should reconcile:
- GSTR-1 data
- Purchase records
- Input Tax Credit
- Reverse Charge Mechanism liabilities
- Output GST
- Electronic cash ledger
- Electronic credit ledger
Don't Treat GSTR-3B as Just Another Return
A mistake in GSTR-3B can directly affect the amount of GST paid and the input tax credit claimed. Proper reconciliation before filing is therefore essential.
8. GST PMT-06 Payment for QRMP Taxpayers – 25 September 2026
Taxpayers under the QRMP Scheme generally make monthly tax payments for the first two months of a quarter through Form GST PMT-06.
For August 2026, the relevant payment deadline is 25 September 2026, subject to the applicable QRMP rules.
The QRMP framework allows eligible taxpayers to file returns quarterly while making monthly tax payments during the first two months of the quarter.
Businesses should calculate their estimated monthly GST liability carefully and ensure sufficient funds are available for timely payment.
9. AOC-4 Filing for One Person Companies – 27 September 2026
For an One Person Company (OPC) with a financial year ending on 31 March 2026, the September compliance calendar includes the AOC-4 filing deadline.
AOC-4 is used for filing financial statements and related documents with the Registrar of Companies.
For OPCs, the applicable filing timeline differs from the standard timeline applicable to companies holding an AGM. Therefore, companies should verify their specific statutory position before filing.
The AOC-4 filing should generally be prepared using the company's approved financial statements and supporting documents.
Before filing, ensure that:
- Financial statements are properly approved
- Required reports are available
- Directors' details are correct
- Digital signatures are valid
- Applicable attachments are complete
- Financial figures match the company's records
10. Annual General Meeting – 30 September 2026
30 September 2026 is a key date for companies whose statutory AGM deadline falls on that date.
An AGM is an important corporate compliance requirement through which shareholders consider matters such as:
- Financial statements
- Directors' reports
- Auditor-related matters
- Appointment or continuation of directors, where applicable
- Declaration of dividend, where applicable
- Other matters requiring shareholder consideration
However, 30 September should not be treated as the universal AGM deadline for every company. The applicable deadline depends on the company's circumstances and statutory requirements, including whether it is holding its first AGM.
Companies should therefore review their individual AGM timeline rather than assuming that every entity must hold its AGM on 30 September.
11. Tax Audit Report – 30 September 2026
For applicable taxpayers whose tax audit report for FY 2025-26 falls due in September, 30 September 2026 is an important deadline.
For FY 2025-26, applicable tax audit reports use the prescribed tax audit forms and related reporting requirements. Taxpayers subject to tax audit should coordinate with their Chartered Accountant well before the deadline.
The audit process may require:
- Books of accounts
- Bank statements
- Sales and purchase records
- GST data
- TDS records
- Fixed asset details
- Loan information
- Expense documentation
- Financial statements
- Other supporting records
Waiting until the final few days can create unnecessary pressure and increase the risk of errors.
12. TDS on Property, Rent, Contractor Payments and VDA Transactions
Your September 2026 compliance calendar may also include challan-cum-statement requirements relating to specified transactions, such as:
- Purchase of immovable property
- Certain rent payments
- Certain payments to contractors or professionals
- Transfer of virtual digital assets
Important 2026 Transition
For transactions governed by the Income-tax Act, 2025 from 1 April 2026 onward, the earlier Forms 26QB, 26QC, 26QD and 26QE have been consolidated into Form 141 for the specified categories of transactions.
Therefore, businesses and taxpayers should not automatically continue using the older form numbers for post-1 April 2026 transactions.
For August 2026 transactions falling under the new framework, the applicable Form 141 requirements should be checked.
September 2026 Compliance Checklist for Businesses
A compliance calendar is useful only when it is converted into an action plan.
GST Compliance
- GSTR-1 for August
- GSTR-1 IFF, where applicable
- GSTR-3B for August
- GST payment
- QRMP PMT-06 payment
- Input Tax Credit reconciliation
Income Tax Compliance
- TDS/TCS payment
- Advance tax instalment
- Applicable tax audit requirements
- Specified challan-cum-statement TDS requirements
Payroll Compliance
- PF payment
- ESI payment
- Professional Tax
- Payroll reconciliation
- Employee deduction records
ROC / Company Compliance
- AOC-4, where applicable
- AGM planning / completion
- Financial statement approval
- Auditor-related documentation
- ROC filing records
Why Businesses Should Maintain a Monthly Compliance Calendar
Compliance should not be managed only when a deadline is approaching.
Avoid Missed Deadlines
Important filings are visible well in advance.
Reduce Late Fees and Interest
Timely payments can help avoid unnecessary financial consequences.
Improve Financial Planning
Tax and statutory payments can be incorporated into monthly cash-flow planning.
Reduce Last-Minute Errors
Teams have sufficient time to reconcile data before submission.
Maintain Better Records
A systematic compliance process creates an organized audit trail.
Improve Corporate Governance
For companies and startups, timely statutory compliance contributes to better governance and record management.
Common Compliance Mistakes to Avoid in September 2026
1. Assuming Every Due Date Applies to Every Business
GST, Professional Tax, ROC and income-tax requirements depend on the taxpayer or entity's status.
2. Filing Without Reconciliation
Submitting GST returns without checking sales, purchase and ITC data can create avoidable discrepancies.
3. Ignoring State-Specific Professional Tax Rules
Professional Tax is not governed by one uniform nationwide due date.
4. Waiting Until the Last Day
Technical problems, missing documents or incorrect data can delay filing.
5. Using Outdated Income-Tax Forms
The 2026 transition to the Income-tax Act, 2025 has changed certain reporting mechanisms. Specified post-April 2026 TDS transactions should be checked for the applicable new form requirements.
6. Treating Compliance as Only a Filing Exercise
Compliance also involves accurate books, reconciliations, documentation, payments and supporting records.
How to Stay Compliance-Ready Throughout September 2026
A simple three-step approach can make monthly compliance easier.
Step 1: Track
Maintain a central calendar containing every applicable statutory deadline.
Step 2: Prepare
Collect invoices, payroll data, bank statements, GST records, TDS details and financial information before the due date.
Step 3: Reconcile and File
Review the information, reconcile differences, make the required payment and complete the applicable filing.
Do not wait until the deadline to discover that your books and statutory returns do not match.
Final Thoughts
September 2026 is a high-activity compliance month for Indian businesses, with important deadlines across GST, income tax, payroll, ROC and audit-related requirements.
From GSTR-1 and GSTR-3B to advance tax, TDS, PF, ESI, AOC-4, AGM and tax audit, businesses need to track multiple obligations simultaneously.
The biggest compliance mistake is not necessarily missing a deadline. It is assuming that a deadline applies—or does not apply—without checking the entity's specific circumstances.
A structured September 2026 compliance calendar helps founders, business owners, accountants and finance teams plan payments, reconcile records and complete statutory filings on time.
For best results, maintain your compliance calendar throughout the year rather than preparing it only when deadlines are close.
Compliance Reminder: Government notifications can extend or modify statutory due dates. Always verify the applicable deadline and requirements before filing or making a payment.
Janki Gupta
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