How to write an invoice

For a UK invoice, record your business and customer details, a unique invoice number, the supply and issue dates, what you supplied, the amounts charged and the total owed. State the payment terms you agreed. A UK VAT invoice needs further details, including your VAT registration number and the tax charged. Requirements differ by country and invoice type.

The Invoice Generator lays these fields out in order and gives you the PDF at the end. Invoice Generator

Writing one, in order

Put your business name, address and contact details at the top.
Add the customer's name and address underneath, labelled clearly.
Give it a unique invoice number, and never reuse one.
Show both the invoice issue date and the supply date if they differ.
List what you supplied, one line each, with quantity and unit price.
Add tax if you charge it, showing the rate and the amount separately.
State the total due and the date you expect it by.
Say how you want to be paid, with the account details if it is a transfer.

The invoice number is the part people get wrong

For a UK VAT invoice, HMRC requires a sequential number from one or more series that uniquely identifies the document. The sequence can begin at 1 or 1001; what matters is that each issued invoice can be traced.

If you cancel an invoice, retain its record instead of deleting it and reusing its number. Where a charge needs reversing, a credit note makes the change visible to the customer and your records.

Payment terms are a deadline, not a hope

Net 30 means thirty days from the invoice date. Write the payment date you agreed with the customer. A missing due date does not mean a UK business debt can never become late; statutory timing rules may still apply.

For qualifying late UK business-to-business payments, statutory interest is eight percentage points above the Bank of England base rate, unless the contract specifies a different rate. Fixed recovery costs may also apply. Check the current rules before adding either charge.

What changes if you are VAT registered

A full UK VAT invoice needs more than a tax total: HMRC lists the tax point, issue date, VAT registration number, rate and amount for each supply, and total VAT in sterling among its required particulars. Check the current HMRC list before relying on a generated document.

Questions people ask next

Do I need a company to send an invoice?

In the UK, no. A sole trader uses their own name and any business name, plus an address for legal documents if they trade under a business name. A VAT number appears only if they are registered.

What if the customer does not pay?

Send a written reminder referring to the invoice number and agreed due date. In the UK, check whether the contract or statutory late-payment rules permit interest and recovery costs before charging them.

Can I invoice in a different currency?

Yes. Show the currency clearly. For a UK VAT invoice, the VAT total must also be shown in sterling; check HMRC's current conversion rules.

Official sources for the UK details

These links describe the rules cited above. Check the current guidance for your own circumstances and country.