Invoicing24 March 2026

How to Write Your First Invoice as a UK Freelancer

By Invoa Team

Sending your first invoice is a milestone — it means you have done the work and now it is time to get paid. But many freelancers stall at this step, unsure what to include, how to format it, or how to make sure the payment actually arrives. This guide covers everything you need to send a professional invoice that gets paid promptly.

What every UK invoice must include

HMRC sets out the minimum information required on an invoice in the UK. For standard (non-VAT) invoices from sole traders and freelancers, you must include:

Your name Your full name or trading name, and your business address

Client details The name and address of the business or individual you are invoicing

Invoice number A unique sequential number — e.g. INV-001. This is important for your records and theirs.

Invoice date The date the invoice was issued — not necessarily when the work was done

Description A clear description of the goods or services provided — enough for the client to match it to what was agreed

Amount The total amount due, clearly stated in your currency

Payment terms When you expect to be paid — e.g. “Payment due within 14 days” or a specific due date

Bank details Your sort code and account number so the client can actually pay you

If you are VAT-registered, additional information is required — including your VAT number, the VAT rate applied, and the VAT amount. See below for more on VAT invoices.

Choosing your invoice number format

Your invoice numbers need to be unique and sequential. You do not need to follow a specific format, but a consistent system makes it easier to track payments and spot missing invoices. Common approaches include:

Simple sequence

INV-001, INV-002, INV-003 — clean and easy to track

Year-based

2025-001, 2025-002 — resets each year, makes it easy to see how many invoices you have raised in a given period

Client-based

ACME-001, ACME-002 — useful if you invoice a small number of clients regularly and want invoices grouped by client

If you use invoicing software like Invoa, invoice numbers are assigned automatically in sequence — so you never have to think about it.

Setting payment terms that work for you

The UK default payment term for business-to-business transactions is 30 days under the Late Payment of Commercial Debts Act. But there is nothing stopping you from setting shorter terms — and most experienced freelancers do.

A note on payment terms

Your payment terms are only enforceable if the client has agreed to them — ideally in writing before the work begins. If you agree 30-day terms in a contract and then invoice with 7-day terms, the 30-day terms apply. Make sure your payment terms are clear and agreed upfront.

Common payment windows used by UK freelancers:

7 days

Common for smaller projects or clients you know well

14 days

A good default for most freelance work — firm but reasonable

30 days

Standard for larger corporate clients with structured accounts payable

Do you need to charge VAT?

Most freelancers starting out do not need to charge VAT. You are only required to register for VAT when your VAT-taxable turnover exceeds £90,000 in any 12-month period (the current threshold as of 2024). Below that threshold, you cannot charge VAT — but you can register voluntarily if it suits your business.

If you are VAT-registered, your invoices must show:

Your VAT registration number
The net amount (before VAT)
The VAT rate (usually 20% standard rate)
The VAT amount charged
The total including VAT

Tips for getting paid on time

The invoice is only the start — here is how to maximise the chance of being paid promptly.

Send the invoice promptly

Invoice as soon as the work is complete, or on the agreed date. Delays in sending the invoice almost always lead to delays in payment.

Send it to the right person

Ask upfront who the invoice should be addressed to and what email address to use. Invoices sent to the wrong contact are a common reason for delayed payment.

Include a purchase order number if required

Many corporate clients will not process an invoice without a PO number. Ask whether one is required before you start the work.

Follow up calmly if the due date passes

A friendly reminder email a day after the due date is completely normal and professional. Most late payments are the result of oversight, not deliberate non-payment.

Use automatic reminders

If you use invoicing software, set up automatic payment reminders to go out a few days before and after the due date. Invoa sends these automatically on the Pro plan — removing the awkwardness of chasing manually.

Send your first invoice in under 2 minutes

Invoa generates professional invoices instantly. Add your client, describe the work, set a due date, and send — all the required fields are included automatically. Your first three invoices are completely free.

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No credit card required. Takes less than two minutes.

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