GST Invoice Generator India 2026

Mandatory fields include: supplier GSTIN; buyer GSTIN (for B2B); unique sequential invoice number; invoice date; HSN/SAC code; description, quantity, and unit; taxable value; applicable GST rate; CGST+SGST or IGST amounts; and grand total. Missing any field can result in ITC denial for the buyer during GST audits.

Use CGST + SGST (each at half the rate) for intra-state supplies — buyer and seller in the same state. Use IGST (at the full rate) for inter-state supplies or export transactions. This tool automatically determines the correct split based on the states you select for seller and buyer.

Yes, from FY 2021-22, HSN/SAC codes are mandatory on all GST invoices. Turnover up to ₹5 crore: 4-digit HSN required. Turnover above ₹5 crore: 6-digit HSN mandatory. Services use SAC (Service Accounting Codes). Incorrect HSN codes can lead to GSTR mismatch notices and ITC denial for buyers.

For goods: at or before delivery. For services: within 30 days of service completion (45 days for banking/NBFC services). Delayed invoicing attracts penalties and can prevent ITC claims if the invoice date falls outside the buyer's current GSTR filing period.

Invoice numbers must be unique, sequential within a financial year (April–March), and can contain letters, numbers, and slashes. Maximum 16 characters. Common format: INV/2026-27/001. Do not reset the sequence mid-year or reuse numbers. Incorrect numbering can attract notices from the GST department.