October 2026 Tax Compliance Calendar: Income Tax, TDS, GST & Audit Deadlines

Summary: October 2026 is a major compliance month for businesses, professionals, employers, GST-registered persons, deductors, collectors and tax professionals, with monthly as well as July-September 2026 quarterly obligations falling due. The most important income-tax development is CBDT Circular No. 07/2026 dated 28 September 2026, under which the specified audit-report due date for Assessment Year 2026-27 has been extended from 30 September 2026 to 21 October 2026 for the covered category. The corresponding return-filing due date has been extended from 31 October 2026 to 21 November 2026. Other important October compliances include TDS/TCS deposit, GSTR-7 and GSTR-8, monthly GSTR-1, quarterly GSTR-1 under QRMP, GSTR-6, CMP-08, monthly GSTR-3B, GSTR-5/5A, PMT-06, GSTR-11 and quarterly TDS/TCS statements. Due dates differ according to taxpayer category, filing frequency, registration status, transaction type and notification-based relief. This calendar should therefore be used as a compliance-control checklist and the applicable statutory and portal position should be verified before filing.

October 2026 Tax Compliance Calendar at a Glance

7 October 2026: TDS and TCS Deposit for September

For applicable deductors and collectors, 7 October 2026 is the due date for depositing tax deducted or collected during September 2026, subject to the specific rules applicable to the deductor, collector and transaction.

The date is also relevant for quarterly TDS deposits where the Assessing Officer has permitted quarterly payment in specified cases.

Tax teams should reconcile the TDS/TCS ledger with challans before payment and verify:

• PAN and deductee/collectee details;
• correct nature and section of payment;
• applicable rate of deduction or collection;
• lower or nil deduction certificates, wherever applicable;
• book entries and payment dates; and
• interest exposure for any delayed deduction or deposit.

October 2026 is particularly important because it also marks the quarterly reporting cycle for the period ending 30 September 2026.

10 October 2026: GSTR-7 and GSTR-8

GSTR-7 – GST TDS

Persons required to deduct tax at source under GST should ordinarily furnish GSTR-7 for September 2026 by 10 October 2026.

The return should be reconciled with deductions made, payments to suppliers and the corresponding tax deposited.

GSTR-8 – GST TCS

Applicable e-commerce operators required to collect tax at source should ordinarily furnish GSTR-8 for September 2026 by 10 October 2026.

Operators should reconcile supplies made through the platform, returns, adjustments and the amount of TCS before filing.

11 October 2026: Monthly GSTR-1 for September

Registered persons filing GSTR-1 monthly should ordinarily furnish the September 2026 statement of outward supplies by 11 October 2026.

Before filing GSTR-1, taxpayers should reconcile:

• sales register and tax invoices;
• credit and debit notes;
• B2B invoice particulars and recipient GSTINs;
• exports and zero-rated supplies;
• e-invoice data, where applicable;
• e-commerce supplies; and
• amendments relating to earlier periods.

Correct GSTR-1 reporting is important because outward-supply data affects recipients’ GST records and subsequent input-tax-credit reconciliation.

13 October 2026: Quarterly GSTR-1 and GSTR-6

Quarterly GSTR-1 under QRMP

For taxpayers filing GSTR-1 quarterly under the QRMP framework, the statement for the July-September 2026 quarter is ordinarily due on 13 October 2026.

This is an important correction to treating 13 October merely as an IFF date. September is the final month of the quarter, and the quarterly GSTR-1 itself becomes relevant.

Taxpayers should verify their actual filing frequency and QRMP status on the GST portal.

GSTR-6 for Input Service Distributors

Input Service Distributors should ordinarily furnish GSTR-6 for September 2026 by 13 October 2026.

ISDs should reconcile eligible input-service invoices, credit notes and distribution of input tax credit before filing.

15 October 2026: Specified Quarterly Income-tax Statements

A number of specialised statements for the quarter ended 30 September 2026 fall due on 15 October 2026 under the Income-tax Rules, 2026.

These include specified reporting obligations applicable to IFSC units, authorised dealers, specified funds, stock brokers and stock exchanges.

These are category-specific obligations and should not be treated as general compliances applicable to every taxpayer.

18 October 2026: CMP-08 for Composition Taxpayers

Taxpayers who have opted for the GST composition levy should ordinarily furnish Form CMP-08 for the July-September 2026 quarter by 18 October 2026.

Before filing, composition taxpayers should verify turnover, applicable composition-tax rate, inward supplies attracting reverse charge and tax already deposited.

20 October 2026: GSTR-3B, GSTR-5 and GSTR-5A

Monthly GSTR-3B

For taxpayers filing monthly, GSTR-3B for September 2026 is ordinarily due on 20 October 2026.

Before filing GSTR-3B, taxpayers should reconcile:

• GSTR-1 with books of account;
• output-tax liability;
• eligible input tax credit;
• GSTR-2B and purchase records;
• ITC reversals and reclaims;
• reverse-charge liabilities;
• electronic cash and credit ledgers; and
• interest or other amounts payable.

GSTR-5 and GSTR-5A

Applicable non-resident taxable persons and specified online information/database access or retrieval service providers should separately examine their 20 October 2026 return obligations.

These are specialised GST compliances and should not be confused with the ordinary GSTR-3B requirement.

21 October 2026: Extended Tax Audit and Specified Audit-Report Deadline

The most significant October 2026 income-tax development is CBDT Circular No. 07/2026 dated 28 September 2026.

For the covered category, the specified audit-report due date for AY 2026-27 has been extended:

Earlier due date: 30 September 2026

Extended due date: 21 October 2026

The extension applies to the specified cases linked to persons mentioned at Sl. No. 2 in the table below Explanation 2 to Section 139(1) of the Income-tax Act, 1961. It should therefore not be treated as a blanket extension of every audit report or certificate.

Where Section 44AB tax audit applies, taxpayers and auditors should complete the applicable Forms 3CA/3CB and Form 3CD, reconciliations and portal procedures within the revised timeline.

Related ITR Due Date Is 21 November 2026

The corresponding ITR due date for the specified category has separately been extended:

Earlier ITR due date: 31 October 2026

Extended ITR due date: 21 November 2026

Accordingly, 21 October 2026 is the audit-report deadline and not the corresponding ITR deadline.

25 October 2026: PMT-06 under QRMP

Taxpayers covered by the QRMP scheme should examine their payment obligation through Form GST PMT-06 by 25 October 2026, where applicable.

The payment position should be checked against the taxpayer’s quarterly filing status and amounts already deposited for the quarter.

28 October 2026: GSTR-11 for Applicable UIN Holders

Persons holding a Unique Identity Number who are required to furnish GSTR-11 in relation to inward supplies and refund claims should examine the 28 October 2026 filing requirement.

This is a specialised compliance and does not apply to ordinary GST-registered businesses.

30 October 2026: Specified Challan-Cum-Statements

Under the Income-tax Rules, 2026, 30 October 2026 is relevant for furnishing Form 141 in respect of specified tax deductions made during September 2026.

Taxpayers dealing with transactions covered by the prescribed challan-cum-statement mechanism should separately identify the applicable provision rather than assuming that the ordinary monthly TDS deposit procedure is sufficient.

31 October 2026: Quarterly TDS and TCS Statements

The quarter ending 30 September 2026 also triggers important TDS and TCS reporting requirements.

Under the Income-tax Act, 2025/Income-tax Rules, 2026 framework, relevant quarterly statements include:

• Form 138 – applicable salary/pension-related TDS statement;
• Form 140 – TDS statement for applicable non-salary payments to residents;
• Form 144 – TDS statement for applicable payments to non-residents; and
• Form 143 – applicable quarterly TCS statement.

For example, the Income Tax Department identifies 31 October 2026 as the Q2 due date for Form 140 and Form 144.

Before filing, deductors and collectors should reconcile:

• challans and book entries;
• PAN details;
• deductee/collectee records;
• applicable rates and transaction classifications;
• lower/nil deduction certificates;
• interest on delayed deduction/deposit; and
• earlier-quarter corrections, where necessary.

Important Month-End Compliance Controls

October is not merely a collection of statutory filing dates. Businesses should also use the month-end close to identify discrepancies before they migrate into subsequent returns.

A practical control checklist includes:

• reconcile GSTR-1, GSTR-3B and books of account;
• compare purchase records with GSTR-2B;
• review ITC reversals and reclaims;
• verify reverse-charge liabilities;
• reconcile TDS/TCS ledgers with challans and quarterly statements;
• review PAN and GSTIN validation errors;
• complete applicable tax-audit documentation and portal acceptance;
• review AIS/TIS and Form 26AS, where relevant;
• track pending notices, outstanding demands and portal communications;
• download and preserve filing acknowledgements;
• maintain maker-checker approval for material filings; and
• update the internal compliance tracker after each filing.

FAQs on October 2026 Tax Compliance Due Dates

1. What is the major income-tax deadline in October 2026?

For taxpayers covered by CBDT Circular No. 07/2026, one of the most significant deadlines is 21 October 2026, the extended due date for the specified audit reports for AY 2026-27.

2. Is the corresponding ITR also due on 21 October 2026?

No. The corresponding return-filing due date for the specified category has been extended from 31 October 2026 to 21 November 2026.

3. What is the monthly GSTR-1 due date for September 2026?

For taxpayers filing GSTR-1 monthly, the ordinary due date is 11 October 2026, subject to any applicable notification-based extension.

4. What is the quarterly GSTR-1 due date for July-September 2026?

For applicable quarterly/QRMP filers, GSTR-1 for the July-September 2026 quarter is ordinarily due on 13 October 2026.

5. When is CMP-08 due for the July-September 2026 quarter?

For applicable composition taxpayers, CMP-08 is ordinarily due on 18 October 2026.

6. When is monthly GSTR-3B due for September 2026?

For taxpayers covered by the ordinary monthly filing timeline, GSTR-3B is generally due on 20 October 2026.

7. When are Q2 TDS statements due?

Applicable quarterly TDS statements for the quarter ended 30 September 2026 are generally due on 31 October 2026 under the current Income-tax Rules, 2026 framework.

8. Can this calendar be followed without checking the relevant portal?

No. A general compliance calendar cannot account for every taxpayer-specific circumstance, state-specific GST position, special category, transaction-specific rule or subsequent statutory extension. The applicable law, notification and relevant portal should be checked before filing.

Key Takeaways

• 7 October: TDS/TCS deposit and specified related compliances.
• 10 October: GSTR-7 and GSTR-8.
• 11 October: Monthly GSTR-1.
• 13 October: Quarterly GSTR-1/QRMP and GSTR-6.
• 18 October: CMP-08 for the July-September quarter.
• 20 October: Monthly GSTR-3B and applicable GSTR-5/5A.
• 21 October: Extended specified audit-report deadline for AY 2026-27.
• 25 October: PMT-06, where applicable.
• 28 October: GSTR-11, where applicable.
• 30 October: Specified challan-cum-statements.
• 31 October: Applicable Q2 TDS/TCS statements and other specified income-tax compliances.
• 21 November: Corresponding extended ITR deadline for the category covered by Circular No. 07/2026.

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Disclaimer: This article is intended solely for general informational and educational purposes and is designed as a broad compliance-control checklist. It does not constitute legal, tax, accounting or other professional advice. Due dates and filing requirements may differ according to taxpayer category, turnover, registration profile, filing frequency, state/UT, transaction type and other facts. Statutory provisions, rules, notifications, circulars, orders, portal utilities, judicial interpretations and due dates may also be amended, extended or otherwise changed after publication. Readers should verify the applicable requirement from the Income Tax Department, GST portal, CBDT, CBIC and other relevant official sources before filing or making any payment and should obtain professional advice where appropriate. TaxGuru, its owners, management, editors, authors, employees and associated persons accept no responsibility or liability for any loss, damage, consequence, decision, delay, interest, late fee, penalty or other action arising from reliance on or use of this article.