GST registration is mandatory for businesses with aggregate annual turnover exceeding ₹40 lakh for goods and ₹20 lakh for services and special category states. Irrespective of turnover, registration is also mandatory for interstate suppliers, e-commerce operators and sellers, casual taxable persons, persons liable under reverse charge, and Input Service Distributors. Voluntary registration is available below the threshold — for businesses that need to issue tax invoices, claim ITC on purchases, or meet requirements of large buyers or government contracts.
The primary returns for most registered taxpayers are GSTR-1, reporting outward supplies filed monthly or quarterly under the QRMP scheme, and GSTR-3B, the summary return with tax payment filed monthly or quarterly. GSTR-9, the annual return, is required for taxpayers with aggregate turnover exceeding ₹2 crore. GSTR-9C, the reconciliation statement certified by a Chartered Accountant, applies to taxpayers exceeding ₹5 crore. Composition dealers file CMP-08 quarterly and GSTR-4 annually. Additional returns apply to non-resident taxable persons, TDS deductors, TCS collectors, and Input Service Distributors.
ITC reconciliation involves comparing the credit reflected in your auto-populated GSTR-2B against the ITC recorded in your purchase register and claimed in GSTR-3B. Discrepancies arise when suppliers have not filed their returns, have filed incorrectly, or have filed late. Under Rule 36(4) of the CGST Rules, ITC can only be claimed to the extent it is reflected in GSTR-2B — meaning unreconciled credits cannot be claimed and must be followed up with suppliers. The GST department actively cross-matches data and issues notices for ITC claimed in excess of GSTR-2B, making regular, systematic reconciliation essential to protect credit claims and avoid demand notices.
A GST notice must be responded to within the prescribed timeline — failing which the department may confirm the demand or assessment ex parte. The first step is to carefully read the notice to understand its basis — whether it relates to return scrutiny under ASMT-10, ITC mismatch, non-filing, or a show-cause notice under Section 73 or 74 of the CGST Act. The response must be technically accurate, supported by evidence, and submitted through the GST portal in the prescribed form. Ignoring or inadequately responding to a notice can result in confirmed tax demands, penalties of up to 100% of tax in fraud cases, and interest at 18% per annum.
E-Invoicing is a system under which every B2B invoice, debit note, and credit note must be registered on the Invoice Registration Portal before it is issued to the buyer. Upon registration, the IRP assigns a unique Invoice Reference Number and generates a digitally signed QR code, which must be printed on the invoice. E-Invoicing is currently mandatory for taxpayers with aggregate turnover exceeding ₹5 crore in any preceding financial year. Invoices not registered on the IRP are treated as invalid — the buyer cannot claim ITC on such invoices and the supplier is exposed to penalties. E-Invoicing data is also auto-populated into GSTR-1, reducing manual data entry when implemented correctly.