A GST invoice is a legal receipt detailing the amount of Goods and Services Tax paid on a purchase. This is a verifiable part of the audit trail of the issuer, and part of expenses for businesses. These receipts may apply to any form of business expense. This is highly relevant to businesses which may be able to claim rebates from the taxation authority for GST paid in purchases for business. GST is usually a separate part of business accounts, and the GST invoices are entered with the amount of GST separate from the cost of goods for that reason.