GST — registration, returns and reconciliation basics

GST registration is mandatory once your turnover crosses the prescribed threshold or if you fall under specific categories like inter-state supply, e-commerce sellers, casual taxable persons or reverse-charge cases.

• Goods: generally ₹40 lakh turnover (₹20 lakh in special category states)
• Services: generally ₹20 lakh turnover (₹10 lakh in special category states)
• E-commerce sellers and inter-state suppliers — required regardless of turnover
• Voluntary registration is allowed and often useful for B2B businesses

Most businesses file GSTR-1 (outward supplies) and GSTR-3B (summary + tax payment). QRMP scheme allows quarterly returns with monthly tax payment for small taxpayers.

• GSTR-1 — outward supplies (monthly or quarterly under QRMP)
• GSTR-3B — summary return with tax payment
• GSTR-9 / 9C — annual return and reconciliation (turnover-based)
• CMP-08 / GSTR-4 — for composition scheme dealers

Input Tax Credit is allowed only if it appears in GSTR-2B (auto-populated from your suppliers' GSTR-1). Mismatch between purchase register and GSTR-2B is a leading cause of notices and ITC denial.

• Reconcile GSTR-2B vs purchase register every month
• Follow up with vendors who haven't filed GSTR-1
• Avoid claiming ITC without invoice or supplier filing

E-way bill is required for movement of goods above the threshold value. E-invoice (IRN) is required for B2B invoices once your turnover crosses the prescribed limit.

Most GST notices arise from preventable issues. Knowing these early avoids penalty and interest.

• GSTR-1 vs GSTR-3B mismatch
• GSTR-3B vs GSTR-2B ITC mismatch
• Non-filing or late filing of returns
• Mismatch with income tax / TDS data