What Makes a Tax Invoice Valid? The Essential Fields

A regular invoice requests payment. A tax invoice also proves that tax was charged correctly — and if it is missing required fields, your client may be unable to reclaim input tax, and you may be unable to defend the charge in an audit.

The fields authorities look for

• The words “Tax Invoice” displayed prominently.
• Seller's legal name, address, and tax registration number (VAT ID, GSTIN, EIN, ABN…).
• Buyer's name and address (and their tax ID for B2B cross-border supplies).
• Unique, sequential invoice number.
• Issue date and, if different, the supply (tax point) date.
• Description, quantity, and unit price of each good or service.
• Tax rate applied to each line, shown separately from the net amounts.
• Total tax charged and the grand total, in a currency the rules allow.

Regional quirks worth knowing

India splits GST into CGST + SGST for intra-state supplies and IGST for inter-state ones. The EU generally requires VAT IDs for cross-border B2B invoicing. Australia wants ABNs and the GST amount in AUD. The pattern is always the same: who, what, when, how much tax.