Tax Invoice Requirements & Compliance

A tax invoice is more than a receipt — it's the legal document your client uses to reclaim VAT or GST and the record your tax authority audits. Miss a mandatory field and the invoice can be rejected, the input tax denied, or penalties applied. This guide covers the exact fields required in the United States, United Kingdom and European Union, plus retention rules and formatting best practice. Every layout in our free invoice template library already includes the fields below.

1. What makes an invoice a "tax invoice"

A plain invoice is a request for payment. A tax invoice additionally records the tax charged so the buyer can claim it back and so tax authorities can trace the transaction. The rules vary by jurisdiction, but three principles are universal:

• The invoice must uniquely identify the seller, the buyer and the transaction.
• Tax must be shown separately from the net amount — never bundled into one figure.
• Invoice numbers must be sequential, gap-free and non-reusable.

2. United States — sales tax invoice requirements

The US has no federal VAT. Sales tax is set by each state (and often each county or city), so requirements vary. The IRS does not mandate an invoice format, but for a document to support a business expense deduction or a resale exemption it should include:

• The word "Invoice" and a unique, sequential invoice number.
• Seller's legal name, address and — if incorporated — EIN (Employer Identification Number).
• Buyer's name and billing address; ship-to address if different.
• Invoice date and, if credit terms apply, the due date.
• Itemised description of goods or services, quantity and unit price.
• Subtotal, sales tax rate and sales tax amount shown on a separate line.
• Total amount due in USD.
• If the buyer is tax-exempt, the resale certificate or exemption number.

Retention: the IRS generally requires businesses to keep invoices for at least 3 years, or 7 years if a claim for a loss from worthless securities or bad-debt deduction is filed.

3. United Kingdom — HMRC VAT invoice requirements

A full UK VAT invoice must be issued by any VAT-registered business supplying another VAT-registered business. HMRC's mandatory fields are:

• A unique, sequential invoice number.
• Your business name, address and VAT registration number (e.g. GB123456789).
• The invoice date (the "tax point") and — if different — the date of supply.
• The customer's name and address.
• A description sufficient to identify the goods or services supplied.
• For each line: quantity, unit price excluding VAT, VAT rate applied, and total excluding VAT.
• Total amount excluding VAT, total VAT payable, and the rate of any cash discount.
• Total amount including VAT in GBP.
• The reason for any zero-rated or exempt supply (e.g. "Zero-rated export — Article 146 EU VAT Directive").

Simplified invoices are allowed for retail sales up to £250 (VAT inclusive). Retention: keep VAT invoices for at least 6 years (10 years if you use the VAT MOSS or IOSS scheme).

4. European Union — VAT Directive 2006/112/EC

EU member states harmonise invoice content via the VAT Directive. A compliant EU VAT invoice must show:

• Date of issue and, if different, date of supply.
• A sequential number that uniquely identifies the invoice.
• Supplier's VAT identification number and full name and address.
• Customer's VAT number for cross-border B2B supplies (reverse-charge rule).
• Description, quantity and unit price of goods or services, net of VAT.
• VAT rate applied and the VAT amount payable, in the currency of the member state.
• Breakdown by VAT rate when multiple rates apply on the same invoice.
• Reference to the applicable article when VAT is not charged (e.g. "Reverse charge — Article 196 Directive 2006/112/EC").
• For margin schemes: a reference to "Margin scheme — travel agents" or "— second-hand goods".

Simplified invoices are permitted for amounts under €100 in most member states. Retention: 10 years is common (Germany, France), 5–7 years elsewhere — always check the local rule.

5. Sequential numbering — why it matters

Every jurisdiction requires invoice numbers to be sequential and gap-free. Tax authorities look for missing numbers as a sign of hidden revenue. Rules of thumb:

• Never reuse a number, even for a cancelled invoice — issue a credit note instead.
• You may reset the counter each year if you prefix with the year: 2026-001, 2026-002…
• Multiple series are allowed (e.g. one per branch) as long as each series is internally sequential.
• If you void an invoice, keep a record of the gap and the reason.

6. Tax breakdown formatting

Show the net amount, tax rate, tax amount and gross amount on separate lines. When several tax rates apply on the same invoice — e.g. standard-rate services plus zero-rated books — group the lines and subtotal each rate before showing the combined total:

Subtotal (20% VAT items)   £400.00
VAT @ 20%                   £80.00
Subtotal (0% VAT items)    £120.00
VAT @ 0%                     £0.00
------------------------------------
Total net                  £520.00
Total VAT                   £80.00
Total due                  £600.00

7. Cross-border supplies and reverse charge

When a UK or EU business invoices a VAT-registered business in another member state, the reverse-charge mechanism usually applies: the seller charges 0% VAT and the buyer accounts for VAT in their own country. The invoice must:

• Show both parties' VAT numbers.
• State "Reverse charge — customer to account for VAT".
• Reference the article of the VAT Directive that grants the exemption.

8. Digital and e-invoicing rules

PDFs sent by email are accepted in the US, UK and across the EU provided the content matches the paper requirements and the file's authenticity and integrity can be demonstrated. Several EU countries (Italy, France, Poland, Spain) now mandate structured e-invoicing (XML via SDI, Factur-X, KSeF, FacturaE) for B2B and B2G transactions — check the local timetable if you sell into those markets.

9. Common compliance mistakes

• Missing VAT/GST number on either party for a B2B cross-border invoice.
• Tax bundled into the unit price instead of shown separately.
• Reusing an invoice number after a client cancellation.
• No article reference when applying reverse charge or an exemption.
• Rounding tax per line and again on the total, producing a mismatched grand total.
• Storing invoices only in email — most authorities require a durable archive.

10. Compliant templates you can use today

All of our invoice templates include the fields required above. Pick a layout, add your VAT/EIN, and download a print-ready PDF:

• Simple invoice template — clean, universal, works for US, UK and EU.
• Freelancer invoice template — VAT-ready with reverse-charge notes.
• Contractor invoice template — labour plus materials, per-line tax.
• Hourly invoice template — hours × rate with automatic tax.
• Service invoice template — recurring services and retainers.

This guide is general information, not tax or legal advice. Requirements change — confirm the current rules with your local tax authority (IRS, HMRC, or your national VAT office) or your accountant before filing.