GST Compliance Calendar 2026: Every Deadline a Chennai Business Must Track

The single most expensive mistake we see Chennai SMEs make is not the tax itself — it's the ₹50/day late fee that compounds silently on unfiled GST returns. Here is the full 2026 GST compliance calendar every Chennai founder should print and stick to the office wall.

Monthly Returns

Return	Who Files	Due Date	Late Fee
GSTR-1	Turnover > ₹5 Cr (monthly filers)	11th of next month	₹50/day (₹20 nil)
GSTR-3B	All regular taxpayers	20th of next month	₹50/day + 18% interest
GSTR-5	Non-resident taxable persons	13th of next month	₹200/day
GSTR-6	Input Service Distributors	13th of next month	₹50/day
GSTR-7	TDS deductors	10th of next month	₹200/day
GSTR-8	E-commerce operators	10th of next month	₹200/day

Quarterly Returns (QRMP Scheme)

Small taxpayers (turnover ≤ ₹5 Cr) can opt into QRMP — quarterly GSTR-1/3B with monthly tax payment via PMT-06. Due dates: 13th (GSTR-1) and 22nd/24th (GSTR-3B) of the month following the quarter.

Annual Returns

• GSTR-9 — turnover > ₹2 Cr — due 31 December of the next FY
• GSTR-9C — turnover > ₹5 Cr — self-certified reconciliation — 31 December
• GSTR-4 — Composition dealers — 30 April
• GSTR-10 — Final return (on GST cancellation) — within 3 months of cancellation. See our GSTR-10 filing service.

Other Critical Filings

• LUT (Letter of Undertaking) — exporters — before 31 March each year for the next FY. See LUT form filing.
• E-invoicing — mandatory for turnover > ₹5 Cr (from FY 2024-25). B2B invoices must be reported to IRP within 30 days.
• E-way bills — for inter-state movement of goods > ₹50,000

Handling Notices

Received ASMT-10, DRC-01 or a scrutiny notice from Chennai GST officers? Do not respond casually — every reply becomes part of the departmental record. Our GST notice response service handles it end-to-end.

Cancelled or Suspended GSTIN?

If your GSTIN was cancelled for non-filing, we file GST revocation within the 90-day window and clear all pending returns.

How Late Fees Add Up

A Chennai retailer we onboarded had not filed GSTR-3B for 14 months. Late fee: ₹50 × 30 × 14 = ₹21,000 per return × 14 = ₹2.94 lakh plus interest at 18% p.a. All avoidable with a calendar reminder.

Do It Right From Day One

If you have not registered yet, start with our GST registration guide and our GST registration service in Chennai. For ongoing compliance, our GST return filing retainer starts at ₹1,499/month.

Also read: Income tax deadlines for Chennai businesses and annual ROC compliance checklist.

Frequently Asked Questions