Different countries have different legal requirements for invoices. Here's what's universally required and what extra fields apply if you're GST/VAT registered.
The Universal Requirements
While specific legal requirements vary by country, the following fields are required or expected on any professional business invoice:
1. The word "INVOICE"
The document must be clearly identified. "Invoice," "Tax Invoice," or "VAT Invoice" depending on local convention.
2. Invoice number
A unique identifier for each invoice. Must be sequential — no gaps, no duplicates.
3. Invoice date
The date the invoice was issued.
4. Your name and address
Your legal name (and trading name if different), your business address, and contact details.
5. Client's name and address
The full name and address of the party being billed.
6. Description of goods or services
A description sufficient to identify what was provided. "Services" alone is not sufficient — be specific.
7. Amount
The total amount due. For multiple items, individual line items with unit prices and quantities.
8. Payment due date
When payment is expected.
9. Payment details
How to pay — bank account details (account name, number, sort code/routing number).
Additional Requirements If You Are GST/VAT Registered
If your business is registered for GST, VAT, HST, or similar consumption tax, additional fields are legally required:
Your tax registration number:
Tax breakdown:
Failing to include your registration number on a tax invoice is a compliance issue that can affect the client's ability to claim input tax credits.
Simplified Invoices
Most countries allow a simplified invoice format for lower-value transactions (thresholds vary — typically £250 in the UK, A$1,000 in Australia). Simplified invoices may omit the client's name and address and show only the gross amount with a note that tax is included, rather than breaking it out separately.
Simplified invoices are only valid for the client to claim input tax if they're below the threshold. For larger amounts, the full tax invoice is required.
What's Different in Different Countries
UK: The document may be called a "VAT Invoice." Companies must include their registered company number. The legal basis for the supply may be needed for reverse charge VAT scenarios.
Australia: Must include ABN. Must state whether GST is included. For amounts over A$1,000, must include the buyer's identity or ABN if they request it for claiming GST credits.
USA: No federal invoice requirements, but individual states have sales tax rules. B2B professional service invoices typically don't collect sales tax. Contractor invoices should include a tax ID if services are above IRS reporting thresholds.
EU: VAT invoices must include the VAT number of both parties for intra-EU B2B transactions. Must state "reverse charge" if applicable.
Common Omissions That Cause Problems
Missing payment details: Clients who want to pay can't do so without your bank account information.
No due date: A specific due date ("Payment due: 30 May 2025") is clearer and more enforceable than "Net 30."
Vague description: "Consulting services" may not satisfy a tax authority or a client's accounts payable requirements.
Wrong GST/VAT treatment: Charging tax when you shouldn't (or not charging when you should) creates compliance issues.
Invoice Compliance in Quotation Expert
Quotation Expert's invoice template includes all required fields by default. Set your business details, GST/VAT registration number, and tax rate once in settings — every invoice you create automatically includes them, formatted correctly on the PDF. No field is accidentally omitted.
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