An invoice is a legal document, not just a request for money. If it's missing the fields HMRC expects, it can delay payment, cause problems at tax time, and — if you charge VAT incorrectly — land you in trouble. The good news is that a compliant UK invoice is simple once you know what goes on it. This guide gives you the exact required fields for both VAT and non-VAT invoices, a plain template you can copy, and the mistakes that most often hold up payment.
What must a UK invoice include?
Every invoice needs a core set of details so it can be identified, matched to a customer, and used as a tax record. The exact list depends on whether you're VAT-registered.
If you are not VAT-registered, your invoice still has to carry the basics. According to GOV.UK's guidance on invoicing and taking payment, it must include:
| Field | What to put |
|---|---|
| Unique identifying number | A sequential number, e.g. 001, 002 or INV-2026-014 |
| Your business name and address | Trading name plus a contact address |
| Your customer's name and address | The person or business being billed |
| Clear description | What you're charging for |
| Date the goods/service were supplied | The supply date (can differ from issue date) |
| Date of the invoice | When you issued it |
| Amount(s) being charged | Line amounts and the total due |
If you trade as a sole trader, you must show your own legal name as well as any business name you use. A "trading as" name is fine, but your real name has to appear somewhere on the document.
What does a VAT invoice need on top of that?
A VAT invoice has stricter rules because it's the document your customer uses to reclaim VAT. You can only issue one once you're registered. GOV.UK's VAT invoice rules require a full VAT invoice to show all of the following:
| Field | What to put |
|---|---|
| Unique sequential invoice number | No gaps or duplicates |
| Your business name, address and VAT number | The VAT number is mandatory |
| Invoice date | Plus the tax point (supply date) if different |
| Customer name and address | The party being billed |
| Description of goods or services | Per line item |
| Quantity and unit price (ex-VAT) | For each line |
| Rate of VAT per item | 20%, 5%, 0% or exempt |
| Total amount excluding VAT | The net total |
| Total VAT charged | Shown separately |
| Total amount including VAT | The gross figure |
The key difference is the breakdown: a VAT invoice has to separate the net amount, the VAT, and the gross total, and it must state the VAT rate applied to each line. If you sell items at different rates (say standard-rated services and a zero-rated book), each line needs its own rate.
Not sure whether you should be charging VAT at all? Our guide on whether you need to charge VAT in the UK walks through the £90,000 registration threshold and when voluntary registration makes sense.
How do I number my invoices?
Invoice numbers must be unique and sequential — that's a hard HMRC requirement, not a nice-to-have. The point is that every invoice can be traced and none can quietly go missing.
You have freedom on the format. Any of these work:
001,002,003— simplestINV-001,INV-002— prefixed2026-001,2026-002— year-prefixed, resets are fine as long as numbers don't repeat within the runACME-INV-0042— client or brand prefix
The two rules that matter: don't reuse a number, and don't go backwards. If you cancel an invoice, don't delete it and recycle the number — issue a credit note instead and keep the original on record. Manually tracking this in a spreadsheet is where most people slip up. If you'd rather not, automatic invoice numbering keeps the sequence correct and lets you set your own prefix pattern.
What payment terms and due dates should I use?
Set a clear payment term and a specific due date — "payment on receipt" is too vague and tends to drift. Common UK terms are:
- Due on receipt — payment expected immediately
- Net 7 / Net 14 — within 7 or 14 days, common for freelancers
- Net 30 — within 30 days, standard for many B2B relationships
State both the term and the actual calendar date the money is due, for example "Payment due within 14 days — due by 3 June 2026." Spelling out the date removes any argument about when the clock started.
If a business customer pays late, you have a statutory right to charge interest under the Late Payment of Commercial Debts (Interest) Act 1998 — Bank of England base rate plus 8%, plus fixed compensation per invoice. We cover the exact sums in how to calculate late payment interest. Adding a short line to your terms — "We reserve the right to charge statutory interest on overdue invoices" — is a fair warning that often gets you paid faster.
How do I invoice with and without VAT?
The difference comes down to one thing: whether you add a VAT line.
Without VAT (you're not registered): list your services or goods, show the amount for each, and give a single total due. Don't mention VAT at all, and never show a VAT number you don't have. Charging VAT before you're registered is an offence.
With VAT (you're registered): show the net price for each line, apply the correct VAT rate, then total up net, VAT, and gross separately. UK rates are 20% standard, 5% reduced, 0% zero-rated, plus exempt supplies that sit outside VAT entirely. The GOV.UK rates of VAT page lists what falls where, and our UK VAT feature handles the per-line maths for you.
A worked example for a registered business billing £500 of standard-rated consultancy:
| Line | Net | VAT rate | VAT | Gross |
|---|---|---|---|---|
| Consultancy (10 hrs @ £50) | £500.00 | 20% | £100.00 | £600.00 |
| Total | £500.00 | £100.00 | £600.00 |
Remember that VAT-registered businesses also have to keep digital records and file returns through compatible software under Making Tax Digital, so it pays to keep your invoicing in a tool that exports cleanly.
What mistakes delay payment?
Most late payments come down to avoidable errors on the invoice itself. The usual culprits:
- No clear due date. "Payment on receipt" gives the customer nowhere to aim. Always state a calendar date.
- Missing or wrong invoice number. Accounts departments often won't process an invoice they can't log against a unique reference.
- Wrong customer details. If the billing name or address doesn't match the purchase order, it gets bounced.
- No payment instructions. Leaving off your bank details, sort code and account number forces the customer to chase you — and they won't, they'll just wait.
- Vague descriptions. "Services rendered" invites questions. Itemise what you did.
- VAT shown when you're not registered, or net/VAT/gross not broken out when you are.
- Sending it to the wrong person. Find out who handles payments and address it to them.
Getting these right the first time removes the back-and-forth that pushes payment dates out by weeks. Setting up payment reminders for anything that does slip past its due date closes the loop without you having to remember to chase.
A copy-paste UK invoice template
Here's a plain text template you can adapt. Fill in your own details, delete the VAT lines if you're not registered, and keep the numbering sequential.
INVOICE
[Your Business Name / Your Name if sole trader]
[Your Address]
[Email] · [Phone]
VAT Number: [only if registered]
Invoice Number: INV-2026-001
Invoice Date: 20 May 2026
Supply Date: 18 May 2026 (if different)
Bill To:
[Customer Name]
[Customer Address]
------------------------------------------------------------
Description Qty Unit Price (ex VAT) Amount
------------------------------------------------------------
[Service / product] 1 £500.00 £500.00
------------------------------------------------------------
Subtotal (ex VAT): £500.00
VAT @ 20%: £100.00
Total Due: £600.00
Payment Terms: Net 14 — due by 3 June 2026
Pay to: [Bank name] · Sort code 00-00-00 · Account 00000000
Reference: INV-2026-001
Drop the three VAT lines and the VAT number if you're not registered, and the same template works as a compliant non-VAT invoice.
Build a compliant invoice for free
You don't have to format any of this by hand. You can build a fully HMRC-compliant invoice in the free invoice editor in a couple of minutes, pick from a range of clean invoice templates, and let the tool handle the numbering and VAT breakdown for you. Invoify's free plan covers 7 contacts, 7 products and 5 emails a month with no card needed; if you outgrow it, Pro is from £7.99/month and removes the limits and the watermark.
This article is general guidance, not tax or legal advice. VAT rules and thresholds change — always check the latest GOV.UK guidance or speak to an accountant about your own circumstances.