Taxpayers should note several important income-tax compliance deadlines during September 2026. By 7 September, tax deducted or collected for August 2026 must be deposited with the Central Government, along with Securities Transaction Tax (STT) and Commodities Transaction Tax (CTT). Form 127 declarations relating to specified purchases without tax collection are also due on this date. 14 September is the due date for issuing Form 132 certificates for tax deducted at source during July 2026.
A major deadline falls on 15 September, when taxpayers must pay the second instalment of advance tax for Tax Year 2026-27. Form 1 relating to client-code modifications by stock exchanges and Form 137 for government TDS/TCS book-adjustment statements for August are also due.
The most significant compliance date is 30 September, covering Form 141 challan-cum-statements and numerous audit reports, certificates and statements under the Income-tax Act, 1961. These include Forms 10B, 10BB, 29B, 29C, 3CA/3CB-CD, 3CE, 3CEA, 56F, 66 and other prescribed reports, mainly for taxpayers whose return filing deadline is 31 October 2026. Timely compliance can help avoid interest, penalties and other statutory consequences.
07-Sep-2026
| Event | Applicable Act | Description |
| Form 127 | Income Tax Act, 2025 | Declaration under section 394(2) of the Act to be made by a buyer for obtaining goods without collection of tax received in the month of August, 2026 |
| Statutory Forms Filling Due Date | Income Tax Act, 2025 | Due date for deposit of Tax deducted/collected for the month of August, 2026. However, all sum deducted/collected by an office of the government shall be paid to the credit of the Central Government on the same day where tax is paid without production of an Income tax Challan |
| Securities Transaction Tax / Commodities Transaction Tax | Other Act | Securities Transaction Tax – Due date for deposit of tax collected for the month of August, 2026 |
| Securities Transaction Tax / Commodities Transaction Tax | Other Act | Commodities Transaction Tax – Due date for deposit of tax collected for the month of August, 2026 |
14-Sep-26
| Event | Applicable Act | Description |
| Form 132 | Income Tax Act, 2025 | Due date for issue of Certificate under section 395(4) for tax deducted at source in the month of July, 2026 |
15-Sep-26
| Event | Applicable Act | Description |
| Advance-Tax Instalment due date | Income Tax Act, 2025 | Second instalment of advance tax for the tax year 2026-27 |
| Form 1 | Income Tax Act, 2025 | Monthly statement to be furnished by a stock exchange in respect of transactions in which client codes been modified after registering in the system for the month of August, 2026 |
| Form 137 | Income Tax Act, 2025 | Due date for furnishing of Form 137 by an office of the Government for TDS/TCS Book Adjustment Statement for the month of August, 2026 |
30-Sep-26
| Event | Applicable Act | Description |
| Form 141 | Income Tax Act, 2025 | Due date for furnishing of Challan-cum-statement of deduction of tax under section 393(1) [Table Sl. No. 2(i), 3(i), 6(ii) and 8(vi)] in the month of August, 2026 |
| Form 10 | Income Tax Act, 1961 | Statement to be furnished to the Assessing Officer/Prescribed Authority under clause (a) of the Explanation 3 to the third proviso to clause (23C) of section 10 or under clause (a) of sub-section (2) of section 11 of the Income-tax Act, 1961 (if the assessee is required to submit return of income on November 30, 2026) |
| Audit Report SWF | Income Tax Act, 1961 | Audit report to be filed by the Sovereign Wealth Fund claiming exemption under clause (23FE) of section 10 of the Income -tax Act, 1961. (if due date of submission of return of income is October 31, 2026) |
| Form 10B | Income Tax Act, 1961 | Audit report under clause (b) of the tenth proviso to clause (23C) of section 10 and sub-clause (ii) of clause (b) of subsection (1) of section 12A of the Income-tax Act, 1961, in the case of a fund or trust or institution or any university or other educational institution or any hospital or other medical institution. (if due date of submission of return of income is October 31, 2026 ) |
| Form 10BB | Income Tax Act, 1961 | “Audit report under clause (b) of the tenth proviso to clause (23C) of section 10 and sub-clause (ii) of clause (b) of sub-section (1) of section 12A of the Income-tax Act, 1961, in the case of a fund or trust or institution or any university or other educational institution or any hospital or other medical institution which is required to be furnished under clause (b) of the tenth proviso to clause (23C) of section 10 or a trust or institution which is required to be furnished under sub-clause (ii) of clause (b) of section 12A (if due date of submission of return of income is October 31, 2026)” |
| Form 10CCB | Income Tax Act, 1961 | Audit report under sections 80-I(7)/ 80-IA(7)/ 80-IB/ 80-IC/80-IAC/80-IE (if due date of submission of return of income is October 31, 2026) |
| Form 10DA | Income Tax Act, 1961 | Report under section 80JJAA of the Income-tax Act, 1961 (if due date of submission of return of income is October 31, 2026 |
| Form 10-IJ | Income Tax Act, 1961 | Certificate to be issued by accountant under clause (23FF) of section 10 of the Income-tax Act, 1961 (if due date of submission of return of income is October 31, 2026) |
| Form 10-IL | Income Tax Act, 1961 | Verification by an Accountant under sub-rule (3) of rule 21AJA Verification (if due date of submission of return of income is October 31, 2026) |
| Form 29B | Income Tax Act, 1961 | Report under section 115JB of the Income-tax Act, 1961 for computing the book profits of the company (if due date of submission of return of income is October 31, 2026) |
| Form 29C | Income Tax Act, 1961 | Report under section 115JC of the Income-tax Act, 1961 for computing Adjusted Total Income and Alternate Minimum Tax of the person other than a company (if due date of submission of return of income is October 31, 2026 |
| Form 3AC | Income Tax Act, 1961 | Due date for filing audit report under section 33AB(2) (if due date of submission of return of income is October 31, 2026 |
| Form 3AD | Income Tax Act, 1961 | Due date for filing audit report under section 33ABA(2) (if due date of submission of return of income is October 31, 2026 |
| Form 3AE | Income Tax Act, 1961 | Audit Report under section 35D(4)/35E(6) of the Income- tax Act, 1961 (if due date of submission of return of income is October 31, 2026) |
| Form 3AF | Income Tax Act, 1961 | Statement regarding preliminary expenses incurred to be furnished under proviso to clause (a) of sub-section (2) of section 35D of the Income-tax Act, 1961 by the assessee (if due date of submission of return of income is October 31, 2026) |
| Form 3CA_CD Form 3CB_CD | Income Tax Act, 1961 | Due date for filing of audit report under section 44AB for the Assessment Year 2026-27 in the case of a corporate assessee or non corporate assessee (who is required to submit his/its return of income on October 31, 2026) |
| Form 3CE | Income Tax Act, 1961 | Audit report under sub-section (2) of section 44DA of the Income-tax Act, 1961 (if due date of submission of return of income is October 31, 2026) |
| Form 3CEA | Income Tax Act, 1961 | Report of an accountant to be furnished by an assessee under sub-section (3) of section 50B of the Income -tax Act, 1961 relating to computation of capital gains in case of slump sale (if due date of submission of return of income is October 31, 2026) |
| Form 56F | Income Tax Act, 1961 | Report under section 10AA of the Income -tax Act, 1961 (if due date of submission of return of income is October 31, 2026) |
| Form 66 | Income Tax Act, 1961 | Audit Report under clause (ii) of section 115VW of the Income-tax Act, 1961 (if due date of submission of return of income is October 31, 2026) |
| Form 9A | Income Tax Act, 1961 | Application for exercise of option under clause (2) of the Explanation to sub-section (1) of section 11 of the Income – tax Act, 1961 (if the assessee is required to submit return of income on November 30, 2026 ) |
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