September 2026 Tax & Compliance Dates: Advance Tax, GST & Revised Audit Timeline
Updated: Sep 28
September 2026 is a critical month in the FY 2026-27 compliance calendar. This guide covers every tax and regulatory deadline that businesses, professionals, and individuals must track — from GST return filings to TDS deposits, advance tax instalments, and statutory returns. Bookmark this page and check it at the start of every month.
Update — 28 September 2026: CBDT changed the specified ordinary AY 2026–27 tax-audit report deadline from 30 September to 21 October 2026 and the related audited return deadline from 31 October to 21 November 2026. Form 3CEB and Q2 TDS remain on separate timelines. Official Income Tax Department announcement.
📅 All September 2026 Compliance Deadlines
7th September 2026 — TDS/TCS deposit: Deposit TDS deducted in August 2026.
11th September 2026 — GSTR-1 (Monthly filers): File outward supply return for August 2026.
13th September 2026 — GSTR-1 IFF (QRMP): Optional IFF for QRMP taxpayers for August 2026.
15th September 2026 — Q2 Advance Tax Instalment: Second advance tax instalment for FY 2026-27 — cumulative 45% of estimated annual tax liability by this date.
20th September 2026 — GSTR-3B (Monthly filers): File summary return and pay GST for August 2026.
22nd September 2026 — GSTR-3B (QRMP — Category I): QRMP taxpayers in Category I states.
24th September 2026 — GSTR-3B (QRMP — Category II): QRMP taxpayers in Category II states.
Tax audit report — ordinary specified AY 2026–27 cases: CBDT changed the Section 44AB report deadline from 30 September to 21 October 2026. Check Section 44AB applicability and complete Forms 3CA/3CB with Form 3CD; the business threshold may rise from ₹1 crore to ₹10 crore where both cash-receipt and cash-payment conditions are met.
Transfer-pricing accountant's report — Form 3CEB: The separate Section 92E report date is generally 31 October 2026, not 30 September. CBDT's ordinary audit extension does not change this transfer-pricing timeline.
Consequences of Missing These Deadlines
GSTR-1 late filing: ₹50 per day (₹25 CGST + ₹25 SGST) for nil-return filers; ₹200 per day (₹100 + ₹100) for others, subject to a maximum of ₹10,000 per return.
GSTR-3B late filing: Same late fee structure as GSTR-1, plus 18% per annum interest on any unpaid tax.
TDS deposit delay: Interest at 1.5% per month from date of deduction to date of deposit, plus potential disallowance of expense under Section 40(a)(ia).
Advance tax shortfall: Interest under Section 234B (1% per month on shortfall from 90% of assessed tax) and Section 234C (1% per month on shortfall at each instalment date).
How PGT & Associates Helps You Stay Compliant
PGT & Associates provides a comprehensive compliance management service for businesses in Ahmedabad and across India — covering monthly GST return filing (GSTR-1, GSTR-3B), TDS computation and deposit, quarterly TDS return filing (Form 24Q, 26Q, 27Q), advance tax computation, and annual return preparation (GSTR-9, ITR, Form 3CD). We proactively track deadlines for all our clients so nothing is ever missed. Contact us at +91-87994-99189 to discuss a compliance retainer.
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