Lesson content
Scroll through numbered sections or jump via the outline.
What you'll take away
- Using personal account for business without clear books.
- Not reconciling GSTR-2B with purchase books monthly.
- Treating GST collected as revenue in pitch decks.
- Ignoring e-invoicing thresholds when you cross turnover limits.
When GST registration is mandatory
Turnover above ₹20 lakh (₹10 lakh in special category states) in a financial year for goods/services.
Inter-state supply, e-commerce sellers, and certain categories have registration regardless of turnover.
Voluntary registration makes sense if you want input tax credit (ITC) on B2B purchases early.
Key returns founders must know
GSTR-1: outward supplies (sales) — monthly or quarterly depending on scheme.
GSTR-3B: summary return with tax payment — monthly for most startups.
GSTR-9 / 9C: annual return and reconciliation (turnover thresholds apply).
Missing GSTR-3B blocks your buyers' ITC and attracts late fees + interest.
Composition scheme — fit or trap?
Small taxpayers can pay tax at fixed rate on turnover with simpler compliance.
Cannot collect GST from customers separately or claim ITC in most cases.
Bad fit if you sell to large companies that need ITC on invoices.
Invoicing rules that prevent disputes
GSTIN, HSN/SAC, place of supply, tax rate, and reverse charge flag (if applicable) on every invoice.
B2B: match legal name on invoice to buyer GST portal name.
Export: LUT or bond for zero-rated supplies — plan before first shipment.
Founder mistakes
- Using personal account for business without clear books.
- Not reconciling GSTR-2B with purchase books monthly.
- Treating GST collected as revenue in pitch decks.
- Ignoring e-invoicing thresholds when you cross turnover limits.