GST is not optional, and it's not as complicated as the compliance industry wants you to believe. But there are enough moving parts — thresholds, return types, payment timelines — that most founders either over-comply (wasting time and money) or under-comply (attracting notices). Here's the practical version.
Do You Actually Need to Register?
GST registration is mandatory if your aggregate turnover exceeds:
- ₹40 lakh for businesses supplying goods
- ₹20 lakh for service providers (₹10 lakh in special category states like J&K, Himachal Pradesh, Uttarakhand)
- Any amount if you supply goods across state borders (inter-state supply)
- Any amount if you sell on e-commerce platforms
If you're below these thresholds, registration is voluntary — but registering voluntarily lets you claim input tax credit on your purchases, which often makes sense even if you're not legally required to.
The Returns You'll File
GSTR-1 (Your Sales)
Reports all outward supplies — invoices you raised. Filed monthly by the 11th of the following month if your turnover exceeds ₹5 crore, or quarterly under QRMP (Quarterly Return Monthly Payment) if it doesn't.
GSTR-3B (Summary + Payment)
A summarised return where you declare your output tax liability, input tax credit, and net payable. You pay GST here. Filed monthly by the 20th for large businesses, or under QRMP for smaller ones. Missing this is the most common way startups attract GST department notices.
GSTR-9 (Annual Return)
Filed once a year by 31 December for the previous financial year. Summarises all your monthly returns. If your turnover is below ₹2 crore, filing is optional — but still advisable to close the year cleanly.
Input Tax Credit — Don't Leave Money on the Table
ITC is the mechanism that makes GST a pass-through tax for businesses. If you've paid GST on purchases — rent, software, professional services, office supplies — you can offset that against your GST liability. But only if:
- Your supplier has filed their GSTR-1 correctly
- The invoice matches what's in GSTR-2B (your auto-generated credit statement)
- You've actually received the goods or services
Reconcile your GSTR-2B against your purchase register every month before filing. Unclaimed ITC is cash left on the table.
Common Mistakes That Lead to Notices
- Missing GSTR-3B deadlines — late fees start from day one (₹50/day, capped at ₹5,000 for nil returns)
- Not reconciling GSTR-1 with your books before filing — mismatches trigger automated scrutiny
- Claiming ITC on blocked credits — personal cars, personal expenses, entertainment
- Not splitting GST correctly on invoices with mixed supply
What Changed in 2026
- E-invoicing is now mandatory for businesses with turnover above ₹5 crore — all B2B invoices must be uploaded to the Invoice Registration Portal (IRP) to get a valid IRN
- The GST Appellate Tribunal (GSTAT) is now operational, providing a faster dispute resolution channel before High Courts
- The amnesty scheme for pending GSTR-9 filings from 2017–2022 ended in March 2025 — unfiled annual returns now attract full penalties
If you're spending more than two hours a month managing GST, something in your process is broken. Muneemji handles end-to-end GST compliance — filing, ITC reconciliation, and notices — for startups across India.