01
Unique invoice number
Give each invoice its own identification number so both you and the customer can refer to the correct document.
Polar First Invoice Builder
How to make an invoice in the UK — and get your first customer ready to pay.
Learn what a UK small-business invoice should contain, how to number invoices, set payment terms, deal with VAT and send a professional invoice without wondering what you have forgotten.
Small business invoicing
Your invoice is not just paperwork. It is the route from completed work to money in the bank.
An invoice tells the customer what has been supplied, what they owe and when they are expected to pay.
GOV.UK sets out information that invoices must contain, including a unique invoice number, supplier and customer details, dates, description of the goods or services, amounts charged and the total owed.
There are additional requirements depending on whether you are a sole trader, limited company or VAT-registered business.
The easier your invoice is to understand and process, the fewer excuses there are for payment to get stuck.
Clear work. Clear amount. Clear due date. Clear payment route.
What should an invoice include?
The core information every invoice needs.
GOV.UK says invoices must contain specific information. Start with these fundamentals and then add any details your customer needs to approve payment.
02
Your business details
Include your business or company name, address and contact information.
03
Customer details
State the name and address of the customer or business you are invoicing.
04
Invoice date
Show the date the invoice was created or issued.
05
Supply date
Include the date the goods or services were supplied where required.
06
Description
Clearly describe the products, services or work that you are charging for.
07
Amounts charged
Show the relevant prices, quantities or charges so the total is understandable.
08
VAT where applicable
VAT-registered businesses have additional invoicing requirements.
09
Total amount owed
Make the final amount the customer needs to pay completely clear.
Small business invoice example
Keep the invoice simple enough to understand at a glance.
Fancy design matters far less than complete, accurate information.
The person who ordered the work may not always be the person who pays the invoice. A clean document helps accounts teams understand what they have received and what needs approving.
INVOICE
From
Northfield Services Ltd
Business Address
Northamptonshire
Invoice to
Example Customer Ltd
Customer Address
United Kingdom
| Description | Qty | Price | Total |
|---|---|---|---|
| Example service | 1 | £500.00 | £500.00 |
Total due: £500.00
Invoice payment terms
Don’t make the customer guess when you expect to be paid.
Agreeing payment terms before work begins is better than discovering afterwards that you and the customer had different expectations.
GOV.UK says businesses can set their own payment terms. Where a payment date has not been agreed, statutory rules can apply.
State a due date
Use a clear calendar date rather than making the customer calculate it themselves.
Match the agreement
Your invoice should reflect the payment terms already agreed with the customer.
Include payment instructions
Explain clearly how the customer should pay.
Add a payment reference
Ask the customer to quote the invoice number where useful.
Include the correct PO number
If the customer requires a purchase order, make sure the relevant reference is on the invoice.
VAT invoices
VAT-registered businesses have extra invoicing rules.
GOV.UK states that VAT invoices contain more information than ordinary invoices. The exact requirements depend on the type and value of the invoice.
Your VAT number
VAT invoices need to show the supplier’s VAT registration number.
VAT rate and amount
Relevant VAT information must be clearly shown rather than simply buried inside the total.
Correct invoice type
Full, simplified and other VAT invoice formats can have different information requirements. Check the current HMRC rules that apply.
How to send an invoice
Send it promptly while the work is still fresh in everyone’s mind.
The Small Business Commissioner recommends submitting invoices promptly rather than allowing completed work to sit uninvoiced.
Every unnecessary delay before sending the invoice creates another unnecessary delay before the payment can arrive.
Invoice to payment
Sending the invoice is the start of the payment process, not the end.
Keep track of what was sent, when payment is due and whether the customer has actually paid.
The Small Business Commissioner also recommends keeping good contact with the person responsible for payment and checking that they have what they need before the due date.
1
Create the correct invoice.
2
Send it to the correct person or accounts address.
3
Record the due date.
4
Track whether payment arrives.
5
Follow up overdue invoices promptly.
Common invoicing mistakes
Five little errors that can turn into a surprisingly long wait for payment.
Make the payment deadline obvious rather than leaving the customer to interpret vague wording.
Describe what was supplied clearly enough for the customer to recognise and approve it.
Incorrect company or billing information can stop an invoice moving through the customer’s process.
If a customer requires a PO number, forgetting it can delay payment considerably.
You cannot be paid for an invoice sitting unfinished on your own laptop.
Polar First Invoice Builder
Turn the first completed job into a professional first invoice.
Polar connects the journey from customer to quote to invoice so you are not repeatedly typing the same business and customer information into disconnected documents.
Build the invoice, keep the important details clear and then carry the payment into the wider Polar Accounts journey.
Invoice FAQs
Creating invoices in the UK: common questions.
What must an invoice include in the UK?
GOV.UK says an invoice must include a unique identification number, your business details, the customer’s name and address, a clear description of what is being charged for, supply and invoice dates, the amounts charged, VAT where applicable and the total amount owed.
How should I number my invoices?
Each invoice should have its own unique identification number. Businesses commonly use a simple sequential system that makes invoices easy to identify and track.
What should a sole trader put on an invoice?
GOV.UK says a sole trader invoice must also include the individual’s name and any business name being used, plus an address where legal documents can be delivered if a business name is used.
What should a limited company put on an invoice?
A limited company should include its full registered company name as it appears on its certificate of incorporation. Other company information requirements may also apply to business documents.
Do I need to put VAT on my invoice?
VAT-registered businesses have specific VAT invoicing requirements. If you are not VAT registered, you should not simply add VAT to an invoice.
What payment terms should I put on an invoice?
Payment terms should reflect what you have agreed with your customer. State the payment due date clearly and explain how the customer should pay.
When should I send an invoice?
Invoice according to the agreement with your customer. The Small Business Commissioner recommends sending invoices promptly after the relevant work or billing point rather than creating unnecessary delay.
Should I include bank details on an invoice?
If you expect the customer to pay by bank transfer, providing the correct payment details and a clear payment reference can make payment easier.
What is the difference between an invoice and a receipt?
GOV.UK describes an invoice as a request or record of an amount that needs to be paid. A receipt acknowledges that payment has already been made.
What happens if an invoice is paid late?
Businesses have legal rights concerning late commercial payments, including circumstances where statutory interest may apply. Check the current GOV.UK guidance before taking action.
From first customer to first payment
Do the work. Send the invoice. Know exactly what needs paying next.
Polar First Invoice Builder helps turn completed work into a clear professional invoice and connects it into the wider customer and accounts journey.