September 2026 Tax & Compliance Due Dates: Advance Tax, GST & Audit Deadline
- shubhamtulsian05
- Jun 14
- 2 min read
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.
📅 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.
30th September 2026 — Tax Audit Report — Form 3CD: Last date to complete and upload the tax audit report under Section 44AB for FY 2025-26. Applicable to businesses with turnover above ₹1 crore (₹2/3 crore for digital transactions) and professionals above ₹50 lakh.
30th September 2026 — Transfer Pricing Audit — Form 3CEB: Last date to file Form 3CEB (Transfer Pricing accountant's report) for FY 2025-26.
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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