How to write an invoice (UK)

This guide is general information based on GOV.UK and HMRC guidance, not tax or legal advice. If your situation is unusual — you sell abroad, use a special VAT scheme, or aren't sure whether you should be VAT-registered — check with HMRC or an accountant.

Do you have to send an invoice?

By law, you must give an invoice when both you and your customer are registered for VAT. Outside that, it isn't strictly required, but it's how nearly every business asks to be paid: it tells the customer exactly what they owe and by when, and it's the record you'll rely on for your accounts and tax return. An invoice is a request for payment; a receipt is confirmation you've been paid. They're different documents.

What a UK invoice must include

GOV.UK lists these as the essentials for any business invoice:

1. A unique invoice number. More on numbering below.
2. Your business name, address and contact details. An email address or phone number the customer can use if there's a query.
3. Your customer's name (or company name) and address.
4. A clear description of what you're charging for. "Website design, 10 hours" beats "Services".
5. The supply date — when you delivered the goods or did the work.
6. The invoice date.
7. The amount or amounts being charged, ideally broken down by line.
8. VAT, if it applies.
9. The total amount owed.

It's also sensible to add payment terms (when payment is due) and how to pay, such as your bank's account name, sort code and account number. Neither is on the legal list, but leaving them off is the quickest way to get paid late.

Extra rules for your type of business

Sole traders

Use your own name, or your business name if you have one. If you trade under a name that isn't your own — "Bright Spark Electrical" rather than "Sam Jones" — put your own name alongside the business name, plus an address where documents can be delivered to you.

Limited companies

Show your full registered company name, exactly as it appears on your certificate of incorporation, including "Limited" or "Ltd". If you choose to list directors' names on the invoice, you must list all of them. Most companies also show their company registration number and registered office address, which company law requires on business letters and order forms.

VAT-registered businesses

If you're registered for VAT, you normally need to issue a proper VAT invoice within 30 days when you make a standard-rated or reduced-rated sale to another VAT-registered business (zero-rated and exempt sales don't need one). A full VAT invoice adds:

• your VAT registration number;
• the time of supply (the tax point), if it's different from the invoice date;
• for each item: the quantity, unit price, VAT rate and amount excluding VAT;
• the total excluding VAT, and the rate of any cash discount offered;
• the total VAT, shown in pounds sterling even if you're invoicing in another currency.

If you're not VAT-registered, don't charge VAT or show a VAT number. Many sole traders add a short line such as "Not VAT registered" to head off questions.

How to number your invoices

Each invoice needs a number that identifies it and never repeats. For VAT invoices HMRC expects a sequential number, and following a sequence is good practice for everyone, because it makes gaps and duplicates obvious. Common formats:

• Simple sequence: 0001, 0002, 0003…
• With a prefix: INV-0001, INV-0002…
• By year: 2026-001, 2026-002… (restart each year, with the year keeping them unique)
• By customer: ACME-001, ACME-002… for businesses with a few big clients

If you make a mistake on an invoice you've already sent, the usual approach is to issue a credit note that cancels it, then a new invoice with a new number, rather than editing or deleting the original.

Payment terms, and what happens if you're paid late

Say clearly when payment is due. If you and your customer haven't agreed a date, GOV.UK says the customer must pay within 30 days of receiving the invoice or the goods or service. Many small businesses use 14 or 30 days; some ask for payment on receipt, or a deposit upfront. Writing an actual due date ("Due: 23 October 2026") is harder to misread than jargon like "Net 30".

When you invoice another business, the law gives you the right to claim statutory interest on late payment — 8% plus the Bank of England base rate — plus a fixed sum for recovery costs of £40, £70 or £100 depending on the size of the debt. You don't have to claim it, but mentioning it in your terms can concentrate minds. These rules apply to business customers, not consumers.

A worked example

Here's how the numbers section of a simple VAT invoice fits together, at the standard 20% rate:

How to write an invoice with Altto

1. Open the Invoice Generator and add your business details: name, email and address (and an optional PNG or JPEG logo).
2. Fill in Bill to with your customer's name and address.
3. Set the invoice number (it starts at INV-0001), the date issued, the due date, the currency, your payment terms and, if the customer gave you one, their purchase order number.
4. Add a line for each item or service with its quantity and unit price.
5. Add any discount, shipping, tax/VAT rate and amount already paid. The subtotal, tax, total and balance due are worked out as you type.
6. Put your bank details in Notes and any late-payment terms in Terms, then click Download PDF.

A few honest notes so the result fits the rules above:

• There's no separate field for a VAT or company registration number, so add it as an extra line in your business address box, where it will appear on the PDF under your name.
• The tool applies one tax rate to the whole invoice. If you're VAT-registered and a single invoice mixes rates (say, standard-rated and zero-rated items), a VAT invoice can show a different rate for each line, but this tool can't, so use accounting software or separate invoices.
• The Shipping box isn't taxed. If you're VAT-registered, delivery charges usually carry VAT too, so add delivery as a normal line item instead.
• If you're not VAT-registered, leave the tax rate at 0. The PDF will still show a tax line of £0.00.
• Nothing you type is uploaded or saved, so Altto doesn't keep a copy — save each PDF somewhere safe and keep track of the next invoice number yourself.

After you've sent it

Keep a copy of every invoice you send, and note when it's paid. HMRC expects you to keep business records for several years — the exact period depends on whether you're a sole trader, a limited company or VAT-registered. If you're sending receipts or supporting photos along with the invoice, our guide on converting JPG to PDF shows how to bundle them into one file.

Common questions