What to include on an invoice: the requirements
TL;DR, the essentials
- A compliant invoice carries around ten to twelve core details: the word “invoice”, a unique number, issue date, both parties’ names and addresses, a clear description of goods or services, the amounts, and any tax.
- If you are VAT registered, you must also show your VAT number, the rate applied and the tax amount for each rate, plus net and gross totals.
- Rules and rates vary by country. This guide covers what is common internationally, with UK VAT as the main reference. Always check your local tax authority.
- Getting a detail wrong can mean your customer cannot reclaim the tax, and repeated errors can trigger penalties.
Issuing an invoice is not just bookkeeping, it is a legal document that lets your customer pay you, reclaim tax where allowed, and lets both sides keep clean records. An incomplete invoice can be rejected, delay payment, or block a VAT claim. Here is a clear, up to date view of what to include on an invoice in 2026, what changes when you are VAT registered, and the special rules for sole traders and very small businesses.
What details must appear on an invoice?
Most tax authorities expect the same core information. In the UK, for example, GOV.UK sets out a clear baseline for a standard commercial invoice. Group the fields into five blocks and check them before you send:
Header and identity
The word “invoice” clearly displayed, your business name and address, and the customer’s name and address. Companies usually add their registration number and, where relevant, registered office.
Number and dates
A unique, sequential invoice number with no gaps or duplicates, the issue date, and the supply date (or tax point) if it differs from the issue date.
Line detail
A clear description of each product or service, the quantity, the unit price, and any discount applied.
Totals
The net amount (before tax), the tax per rate, and the gross total due. The currency should be unambiguous.
Payment terms
The amount owed, the due date or payment terms, and how to pay (bank details or a payment link). Late payment terms are optional but wise.
Read field by field, a complete invoice includes:
- The word “invoice”, so the document is not mistaken for a quote or delivery note.
- A unique invoice number, based on a continuous sequence with no gaps or duplicates (for example 2026-001, 2026-002).
- The issue date, and the supply date or tax point when goods were delivered or the service completed, if different.
- Your business details: trading name, address, and company registration number where you are incorporated.
- The customer’s details: name or business name and address.
- A clear description of each item or service, with quantity and unit price.
- Any discount agreed at the point of sale.
- The totals: net (pre tax) amount, tax by rate, and the gross total payable.
- Payment terms: due date or period, and payment method or bank details.
Selling to consumers
When you sell to individuals rather than businesses, some fields (such as the buyer’s tax number) may not apply, but a plain description, price and your identity are still expected. Consumer protection rules, including statutory warranties, may add their own wording depending on the country.
How do you show net, VAT and gross amounts?
If you are registered for VAT (or an equivalent sales tax), your invoice becomes a tax invoice and must carry extra detail. According to GOV.UK guidance on VAT invoices, a full VAT invoice in the UK must show your VAT registration number, the rate of VAT charged per line, the total net amount excluding VAT, the total VAT amount, and the gross total. Where different rates apply, each rate must be shown separately.
The arithmetic itself is simple. Using a 20% rate as an example (the UK standard rate, other countries differ):
- From net to gross: gross = net × 1.20. A net amount of 1,000 gives 1,200 gross.
- The VAT from a gross amount: VAT = gross ÷ 1.20 × 0.20. On 1,200 gross, the VAT is 200.
- The net from a gross amount: net = gross ÷ 1.20, so 1,000 for 1,200 gross.
An invoice should always let anyone reconstruct the net base, the tax collected and the gross total without ambiguity, rate by rate.
Rates and thresholds vary
VAT and sales tax rates, registration thresholds and invoice rules differ significantly from one country to another, and can change from year to year. Treat the figures above as an illustration only, and confirm the current rules with your national tax authority before invoicing.
Quick quiz
A service billed at 500 net, at a 20% rate, what is the gross total?
Generate compliant invoices automatically
Good software builds every required field in and calculates the tax for you. See our picks.
What about sole traders and small businesses?
If you are a sole trader or a very small business that is not registered for VAT, your invoices are simpler. You still need the core details (identity, unique number, dates, description, amounts and payment terms), but you do not charge or show VAT, and you have no VAT number to display.
- Show your own name and, if you trade under a business name, that name too, along with an address where you can be contacted.
- Do not add a VAT line or VAT number if you are not registered. Displaying VAT you are not entitled to charge is a serious error.
- If your turnover crosses your country’s VAT registration threshold, you must register and start issuing tax invoices, so keep an eye on your running totals.
Good habit
Save your default identity, numbering format and payment terms as a template in your invoicing tool. Every new invoice inherits them automatically, so nothing gets forgotten and your numbering stays sequential.
Do invoices need to be electronic?
More and more countries are moving from paper and PDF invoices toward structured electronic invoicing (e-invoicing), often routed through approved platforms or government portals, especially for business to business and public sector transactions. The timelines, formats and platforms differ by country and are still rolling out, so there is no single global rule.
- A PDF emailed to a client is fine in many places today, but structured e-invoicing formats are increasingly mandated, particularly for B2B and public contracts.
- Electronic invoices carry the same required content as paper ones, plus, in some regimes, additional structured fields.
- Check your national rules and your customer’s requirements before assuming a plain PDF will always be accepted.
Plan ahead
If your country is introducing mandatory e-invoicing, a plain PDF may stop being compliant for some transactions. Make sure your invoicing tool can produce the required structured format and connect to any approved platform.
In practice, invoicing software that stays current with local formats is the safest way to keep your documents compliant as the rules evolve. That is exactly what our dedicated comparison looks at.
Ready for structured e-invoicing
Our selection highlights tools that keep pace with electronic invoicing formats and approved platforms.
What happens if an invoice is incomplete?
An invoice that omits a required detail, or shows it incorrectly, causes real problems. The most immediate is that your customer may be unable to reclaim the VAT, which strains the commercial relationship and often means the invoice is sent back to you. Beyond that, tax authorities in many countries can apply penalties for invoices that do not meet the legal requirements, and missing or inaccurate records can weigh against you in an audit. Exact penalties vary by jurisdiction, so this is not an area to improvise. Getting the details right the first time is far cheaper than fixing them later.
Next step
To issue compliant invoices without the manual work, see our comparison of the best invoicing software 2026, or browse the full invoicing hub for guides and tools.
Frequently asked questions
What must be included on an invoice?
An invoice should include the word “invoice”, a unique sequential number, the issue date (and supply date if different), your business name and address, the customer’s name and address, a clear description of the goods or services with quantity and unit price, any discount, the net and gross totals, and payment terms. If you are VAT registered, add your VAT number, the rate per line and the tax amount. Exact requirements vary by country.
Do I need to show VAT if I am a sole trader?
Only if you are registered for VAT. A sole trader below the registration threshold does not charge VAT, shows no VAT number and no VAT line, and simply lists the amounts due. Once your turnover crosses your country’s threshold, you must register and start issuing full tax invoices.
Does an invoice number have to be sequential?
Yes. Each invoice needs a unique identifier based on a continuous sequence with no gaps or duplicates, so your records can be traced and audited. Most invoicing software generates this automatically to prevent errors.
Is a PDF a valid invoice?
In many countries a PDF invoice is accepted today, provided it contains all the required details. However, several jurisdictions are introducing mandatory structured e-invoicing, especially for business to business and public sector transactions, where a plain PDF may no longer be compliant. Check your national rules.