What You Need to Know: October 2026 GST & TDS Filing Deadlines

C P C Services — Thu, 08 Oct 2026 15:31:48 +0000

Every deadline your business needs to hit in October 2026 — with the one date that closes the door on FY 2025-26 ITC permanently.

October 2026 is a month with consequences. The 20 October deadline for GSTR-3B is the final date to claim any unclaimed input tax credit from FY 2025-26. Miss it and that credit is gone permanently — no extension, no reversal, no recovery. The 31 October deadline brings the ITR for audit cases, Q2 TDS return, and ITR for domestic companies all due on the same day.

For QRMP taxpayers, October is also the quarter-end return month — the Q2 GSTR-3B (covering July, August, September) is due 22 or 24 October. And for monthly filers, the routine September GST cycle continues: GSTR-1 by 11 October, GSTR-3B by 20 October.

This blog covers every October 2026 compliance deadline, what each involves, what it costs to miss, and the specific actions to take before the month ends.

IMPORTANT WARNING

20 October 2026 — The most important GST deadline of the year.

The September 2026 GSTR-3B, due on 20 October 2026 for monthly filers, is the last return in which FY 2025-26 input tax credit can be claimed. Any ITC from April 2025–March 2026 invoices that has not appeared in GSTR-2B by 14 October 2026 and been claimed in this return is permanently lapsed. No extensions are granted for this provision.

If you have outstanding FY 2025-26 supplier invoices, the window to resolve them closed with September’s GSTR-1 filing on 11 September. October 20 is the final filing deadline — not another chance to fix missing invoices.

All October 2026 Compliance Deadlines at a Glance

Due Date	Type	Form / Filing	Who It Applies To	Cost of Missing It
7 Oct 2026	INCOME TAX, TDS & CORPORATE	TDS Deposit	Non-government deductors: deposit TDS deducted in September 2026	1.5%/month interest from deduction date + expense disallowance risk
7 Oct 2026	INCOME TAX, TDS & CORPORATE	TCS Deposit	E-commerce operators and TCS collectors: deposit TCS for September 2026	Same interest treatment as TDS default
20th Oct 2026	INCOME TAX, TDS & CORPORATE	Furnishing of Audit Reports	Extended Due date for Furnishing of Audit Report u/s 44AB of the Income-tax Act 1961	Late Fee of 0.5% of Turnover or Rs.150000.00 which is lower.
30 Oct 2026	INCOME TAX, TDS & CORPORATE	TDS on Property	Deposit TDS on immovable property purchases made in September 2026 (Form 141)	₹200/day late fee + interest on late deposit
31 Oct 2026	INCOME TAX, TDS & CORPORATE	TDS Return Q2	File quarterly TDS/TCS return for July–September 2026 (Forms 138,140,144)	₹200/day late fee; deductees cannot see TDS credit in Form 168
31 Oct 2026	INCOME TAX, TDS & CORPORATE	ITR — Audit Cases	Businesses and professionals whose accounts require statutory audit: file ITR for FY 2025-26	₹5,000 late fee; loss of old tax regime option; loss of carry-forward losses
21 Nov 2026	INCOME TAX, TDS & CORPORATE	ITR — Companies	All domestic companies: file ITR-6 for FY 2025-26 (AY 2026-27)	₹5,000 late fee; interest under Section 234A on outstanding tax
10 Oct 2026	GST	GSTR-7	TDS deductors under GST: monthly return for September 2026	₹50/day late fee; blocks deductee’s GST TDS credit
10 Oct 2026	GST	GSTR-8	E-commerce operators (TCS under GST): monthly return for September 2026	₹50/day late fee; seller cannot claim TCS credit
11 Oct 2026	GST	GSTR-1	Monthly filers (turnover >₹5 Cr): outward supply return for September 2026	₹50/day late fee; buyer ITC blocked; hard-locked GSTR-3B cannot compensate
13 Oct 2026	GST	GSTR-1 (QRMP)	QRMP quarterly filers: outward supply return for Q2 (July–September 2026)	₹50/day late fee; Q2 buyer ITC blocked for entire quarter
13 Oct 2026	GST	GSTR-5	Non-resident taxable persons: return for September 2026	₹50/day late fee
13 Oct 2026	GST	GSTR-6	Input Service Distributors: return for September 2026	₹50/day; ITC distribution to branches delayed
20 Oct 2026	GST	GSTR-3B — FINAL ITC DATE	Monthly filers (>₹5 Cr): summary return + payment for September 2026. LAST DATE TO CLAIM FY 2025-26 ITC.	₹50/day late fee + 18% p.a. interest + permanent loss of all unclaimed FY 2025-26 ITC
22 Oct 2026	GST	GSTR-3B (QRMP Cat 1)	QRMP — Category 1 states: quarterly GSTR-3B for Q2 (Jul–Sep 2026)	Same as above; Q2 ITC shortfall cannot be corrected after filing
24 Oct 2026	GST	GSTR-3B (QRMP Cat 2)	QRMP — Category 2 states incl. Haryana, Delhi, UP: Q2 GSTR-3B	Same as above
25 Oct 2026	GST	PMT-06	QRMP taxpayers: monthly GST payment for September 2026	18% p.a. interest on deficit; quarterly GSTR-3B will show underpayment
30th Oct	ROC	AOC-4	Furnishing of Financial Statements	₹100 per day with no upper ceiling or maximum cap

The ITC Lapse Deadline: What Happens on 20 October 2026

This is the deadline that no other compliance calendar article typically explains with the clarity it deserves. So we will.

The rule: Under Section 16(4) of the CGST Act, input tax credit for FY 2025-26 can only be claimed until the earlier of the due date for the September 2026 GSTR-3B return, or the date of filing the annual GSTR-9 return for FY 2025-26.

The practical deadline: For monthly filers, the due date for September 2026 GSTR-3B is 20 October 2026. For QRMP filers, it is 22 or 24 October 2026.

What this means: Any purchase invoice from FY 2025-26 (April 2025 to March 2026) that has not been claimed as ITC in any GSTR-3B up to and including the September 2026 return is permanently gone after 20 October. The credit cannot be reclaimed, carried forward, or refunded.

KEY TAKEAWAY

Three scenarios where this matters right now:

Supplier filed GSTR-1 late in September: If a FY 2025-26 invoice finally appeared in your September GSTR-2B (generated 14 October), you can claim it in the September GSTR-3B due 20 October. If the invoice has still not appeared in GSTR-2B by 14 October, the credit is permanently lost.
You missed claiming ITC in a previous month: If you have unclaimed ITC sitting in earlier GSTR-2B statements that you did not claim in that period’s GSTR-3B, you can still claim it now in September’s GSTR-3B — provided the invoice is from FY 2025-26. This is your last opportunity.
Reconciliation not yet done: If you have not completed the GSTR-2B vs purchase register reconciliation for Q2 (August–September), do it immediately. Any Bucket C items (in books, not in GSTR-2B) from FY 2025-26 that have not appeared yet are irrecoverable after 20 October.

TDS Compliance in October 2026

TDS Deposit — 7 October 2026

TDS deducted from all payments made in September 2026 must be deposited by 7 October. This includes salary TDS, contractor TDS, professional fee TDS, rent TDS, and any other payment where TDS applies under the Income Tax Act, 2025 (Section 393).

Section reference reminder: All TDS on payments made after 1 April 2026 is governed by Section 393 of the Income Tax Act, 2025. Challans and TDS returns must quote the new section references — not the old 194C, 194J, 194H etc. If your accounting software has not been updated, portal validation may fail.

Q2 TDS Return — 31 October 2026

The quarterly TDS return for July–September 2026 (Q2 of Tax Year 2026-27) must be filed by 31 October 2026. This is separate from the monthly TDS deposit obligation — the return is an independent filing that reports all deductions made during the quarter.

Key forms:

Form 138: Salary TDS — employer deducting from employee salaries across all designations and salary structures
Form 140: Non-salary TDS to residents — contractors, professionals, rent, interest, commission
Form 143: TDS on payments to non-residents and foreign companies

What the Q2 return must reflect: All TDS deducted in July, August, and September 2026. All challans deposited for those months (typically by 7 August, 7 September, and 7 October). Any corrections to Q1 (April–June) TDS returns should be filed as revised returns separately — not mixed into Q2.

ADVISORY

31 October convergence point: The Q2 TDS return (31 Oct) all fall on the same day. For any business that has a tax audit, the finance team is simultaneously managing audit finalisation, TDS return compilation, and ITR preparation. Plan backwards from 31 October — do not leave all three to the final week.

→ Explore Corporate Compliance Services | Talk to CPC Services

CPC INSIGHT

For QRMP taxpayers, the October GSTR-3B is unusually important because it covers an entire quarter and is simultaneously the last filing for FY 2025-26 ITC. CPC Services completes a three-month Q2 reconciliation for QRMP clients before this filing — checking three months of GSTR-2B data, all ITC reversal obligations, and the FY 2025-26 lapse position. A single missed credit at this stage is permanently unrecoverable.

→ Explore Indirect Tax & GST Services | Visit the Compliance Desk

ITR Filing Deadlines in October 2026

ITR for Audit Cases — 31 October 2026

Businesses and professionals whose accounts are required to be audited under Section 44AB of the Income Tax Act, 1961 (applicable to FY 2025-26) must file their ITR by 31 October 2026. The tax audit report (Form 3CA/3CB/3CD) must have been uploaded by 30 September 2026.

Who this covers:

Business taxpayers with turnover above ₹1 crore (₹10 crore if cash transactions are below 5% of total)
Professional taxpayers with gross receipts above ₹50 lakh (₹75 lakh under presumptive scheme if opted out)
Any taxpayer who has triggered audit under other provisions (Section 44AD opted out in a previous year but income is below 8%/6%)

For directors and partners: If the company or firm requires an audit, the director or partner's personal ITR — if linked to the company's financials — may also have an October 31 deadline rather than the August 31 deadline. Verify with your CA which deadline applies to your personal return.

ITR for Domestic Companies — 31 October 2026

All domestic companies (private limited, public limited, OPC) must file ITR-6 for FY 2025-26 by 31 October 2026. This includes companies whose turnover is below the audit threshold — the company ITR deadline is October 31 regardless of whether a tax audit applies.

IMPORTANT WARNING

Missing 31 October means losing the old tax regime permanently for that year.

For individual taxpayers (proprietors, partners, professionals) filing audit-case ITRs, a belated return filed after 31 October is treated under the new tax regime by default. For a business owner with significant 80C deductions, home loan interest, and professional expenses under the old regime — the difference in tax can easily exceed ₹1–2 lakh. File by 31 October, not as an afterthought.

October Cash Flow Planning: Sequencing Your Compliance Obligations

October’s obligations are spread across the month but require planning from the first week. Here is the sequenced action plan:

Date	Action Required	Why It Cannot Wait
7 Oct	Deposit September 2026 TDS and TCS	1.5%/month interest from 1 October if missed. Most expensive per-day default in the calendar.
11 Oct	File September GSTR-1 (monthly filers)	Hard-locked GSTR-3B cannot compensate for GSTR-1 errors. File accurately — use GSTR-1A if correction needed before GSTR-3B.
13 Oct	File Q2 GSTR-1 (QRMP filers: Jul–Sep quarter)	Q2 buyer ITC for the entire quarter depends on this filing. Three months of invoices in one return — review carefully.
14 Oct	GSTR-2B generated — begin ITC reconciliation immediately	October GSTR-3B is due in 6 days. This is your final chance to identify unclaimed FY 2025-26 ITC before the window closes.
18 Oct	Complete GSTR-2B reconciliation; verify all FY 2025-26 ITC claimed	Any unclaimed FY 2025-26 ITC not in September GSTR-3B lapses permanently after 20 October.
20 Oct	File September GSTR-3B — the FY 2025-26 ITC final deadline	After this date, all FY 2025-26 unclaimed ITC is gone. Pay net GST liability before filing.
22/24 Oct	File Q2 GSTR-3B (QRMP filers — Cat 1 by 22nd, Cat 2 by 24th)	Same ITC lapse rules apply to QRMP filers. Full Q2 reconciliation must be done before submission.
25 Oct	PMT-06 payment for September (QRMP taxpayers)	Monthly GST payment even under quarterly filing. 18% p.a. interest on deficit.
28 Oct	Finalise Q2 TDS return data; verify all challans	31 Oct TDS return requires accurate Q2 data. Match deductions against salary registers, vendor payment records.
31 Oct	File Q2 TDS return 138/140/143 (earlier 24Q/26Q/27Q)	All three are due on the same day. Plan CA bandwidth. Late filing fee ₹200/day for TDS return; ₹5,000 for late ITR.

What Each Missed Deadline Costs in October

Filing	Late Fee	Interest	Worst-Case Consequence
TDS Deposit (7 Oct)	None	1.5%/month from deduction date	30% expense disallowance + prosecution risk for persistent defaults
GSTR-1 (11 or 13 Oct)	₹50/day	None directly	Buyers’ ITC blocked — business relationship stress and potential disputes
GSTR-3B (20/22/24 Oct)	₹50/day, capped ₹5,000	18% p.a. on unpaid tax	Permanent loss of all FY 2025-26 ITC — potentially lakhs for QRMP businesses filing in October
Q2 TDS Return (31 Oct)	₹200/day (uncapped)	N/A if deposit done	Deductees cannot see TDS credit in Form 26AS; potential penalty ₹10,000–₹1 lakh for persistent default