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What Every Invoice Legally Needs to Include

Your invoice isn’t just a payment request — it’s a document with legal weight. Missing information can delay payments, cause tax problems, or even make your invoice unenforceable. Here’s what you actually need to include, broken down by country.

Universal requirements (everywhere)

Regardless of where you operate, every invoice should include:

✓Your business name and contact info — Name, address, email, phone
✓Client’s name and contact info — Who you’re billing
✓Unique invoice number — Sequential, not random (INV-001, INV-002, etc.)
✓Invoice date — When the invoice was issued
✓Due date or payment terms — “Due on receipt,” “Net 30,” etc.
✓Description of goods or services — What you did, with enough detail to be clear
✓Amount due — Line items, quantities, rates, and total
✓Payment methods — How to pay you (bank details, PayPal, etc.)

🇺🇸 United States

The US has no federal law specifying exact invoice requirements for most businesses. However, for tax purposes and legal enforceability, you should include everything in the universal list above, plus:

✓Sales tax (if applicable) — Shown as a separate line item
○EIN (optional) — Not required on invoices but useful for B2B

States with sales tax require you to show tax separately. If you’re selling services (most freelancers), check your state — many exempt services from sales tax entirely.

🇬🇧 United Kingdom

HMRC has specific rules. Your invoices must include:

✓Company registration number — If you’re a limited company
✓VAT number — If VAT-registered (threshold: £85,000/year)
✓VAT amount — Shown separately, with the rate applied
✓Registered office address — For limited companies

Sole traders under the VAT threshold can issue simpler invoices. But once you cross £85,000 in annual revenue, full VAT invoices are mandatory.

🇪🇺 European Union

The EU VAT Directive sets minimum requirements for VAT invoices across all member states:

✓VAT identification number — Yours and the client’s (for B2B)
✓VAT rate and amount — Per line item or for the total
✓Sequential invoice number — Gaps in numbering can trigger audits
✓Reverse charge note — For B2B cross-border services (“VAT reverse charge applies”)

Individual countries may have additional requirements. Germany, for example, requires your tax number (Steuernummer) or VAT ID on every invoice.

🇦🇺 Australia

The ATO requires “tax invoices” for GST-registered businesses:

✓ABN (Australian Business Number) — Required on all invoices
✓“Tax invoice” label — Must literally say “Tax Invoice” on it
✓GST amount — For invoices over $82.50 (including GST)

For invoices under $1,000, a simplified tax invoice is acceptable. Over $1,000, you need to include the buyer’s ABN as well.

Common mistakes

  • No invoice number — Makes tracking impossible and looks unprofessional
  • Missing due date — “Please pay soon” is not a due date
  • Vague descriptions — “Services rendered” tells the client nothing
  • No payment instructions — Don’t make them ask how to pay you
  • Wrong currency — Always specify currency, especially for international clients

The easiest way to not miss anything? Use a tool that includes all the right fields. Our free invoice generator covers every field mentioned above — business details, tax, payment terms, custom line items, and more. Check out the accountant template or lawyer template for industry-specific examples.

Create Your Invoice →

Frequently Asked Questions

Is an invoice a legal document?

An invoice is a commercial document, not a legal contract. However, it serves as evidence of a transaction and can be used in legal disputes. Proper invoices are also required for tax compliance in most countries.

Do I need to include my tax ID on invoices?

It depends on your country. In the EU, a VAT number is required on invoices for VAT-registered businesses. In the US, your EIN is not always required on invoices but is needed for tax reporting. In Australia, your ABN is required.