Missing a GST deadline can cost your startup 2% of your tax liability per month in late fees — and that adds up fast. Whether you're a bootstrapped company or freshly funded, staying on top of GST compliance isn't optional. Here's every deadline your finance team needs to track.
GSTR-1: Outward Supplies (Monthly)
GSTR-1 captures all your outward supplies — essentially every invoice you've raised during the month. This return is due by the 11th of the following month. For example, your January 2026 GSTR-1 is due by February 11, 2026.
For startups with annual turnover below ₹5 crore, you can opt for the Quarterly Return Filing Monthly Payment (QRMP) scheme. Under QRMP, GSTR-1 is filed quarterly instead of monthly, with dues on the 13th of the month following the quarter.
GSTR-3B: Summary Return (Monthly)
GSTR-3B is your summary return — it consolidates your output tax, input tax credit (ITC), and net tax payable. Due by the 20th of the following month. This is where you actually pay your GST.
Late filing attracts a late fee of ₹50 per day (₹20 per day for nil returns) plus 18% annual interest on outstanding tax. For a startup with even ₹2 lakh monthly GST liability, a 30-day delay costs ₹4,000+ in penalties alone.
GSTR-9: Annual Return
The annual return consolidates your entire year's GST activity. Due by December 31 of the following financial year. So your FY 2025-26 annual return is due by December 31, 2026.
If your turnover exceeds ₹5 crore, you'll also need GSTR-9C — a reconciliation statement audited by a CA. Plan ahead. This is not something you want to rush in the last week of December.
ITC Reconciliation: The Hidden Deadline
Input Tax Credit claims for a financial year must be reconciled by the due date of GSTR-3B for September of the following year, or the date of filing the annual return — whichever is earlier. Miss this, and you lose the ITC permanently.
For many startups, unclaimed or mismatched ITC is the biggest source of cash leakage. Regular monthly reconciliation between your books and GSTR-2A/2B is essential.
Quick Reference Calendar
How to Stay Ahead
The most common reason startups miss deadlines is disorganised bookkeeping. When your books aren't closed monthly, filing becomes a scramble. Here's what works:
- Close books within 5 days of month-end
- Reconcile ITC monthly, not annually
- Set calendar reminders 3 days before each due date
- Use a GST compliance tracker or work with a team that manages it end-to-end
At TxCount, GST compliance is one of our core offerings. We handle everything from monthly GSTR-1 and GSTR-3B filings to annual returns and ITC reconciliation — so you can focus on building your business instead of tracking deadlines.
Published by the TxCount Team — AI-powered compliance and fractional CFO services for growing businesses.