How to Invoice a Client as a UK Freelancer

Start With the Basics

An invoice is a formal request for payment. It needs to be clear, complete, and professional. Missing information is the most common reason invoices get delayed or queried by a client's accounts team.

As a UK sole trader, there's no single legal format you must follow, but there are details that should always be there.

What to Include on Every Invoice

Your details: Your full name (or business name), address, and contact email. If you're VAT registered, include your VAT number.

Client details: The company or person's full name and billing address. Get this right. An invoice addressed to the wrong entity can bounce back from accounts teams and delay payment by weeks.

Invoice number: Use a sequential numbering system and never repeat a number. INV-001, INV-002 and so on. This makes your records easier to audit and your client's accounts team happier.

Invoice date and due date: State clearly when the invoice was raised and when payment is due. "30 days from invoice date" is standard, but 14 days is increasingly common and perfectly reasonable for professional services.

Description of work: Be specific. "Consultancy services" tells no one anything. "Website redesign: homepage and three service pages, delivered 15 March 2026" is clear, defensible, and much less likely to be queried.

Amount: Show the net amount, VAT if applicable, and the total. If you have multiple line items, subtotal each one.

Payment details: Your bank name, sort code, and account number. Every invoice, every time. Don't assume the client still has your details from last time.

How to Send It

PDF is the standard. It looks professional, can't be accidentally edited, and works in every email client. Most invoicing tools generate PDFs automatically. If you're using a Word template, save it as PDF before sending.

Email it directly to the person responsible for payment. If it's a larger company, that might be a specific accounts payable address. Ask before you assume.

When to Send It

On the day you finish the work. Not at the end of the month. Not when you remember. The moment you deliver, send the invoice. Every day you wait is a day added to your payment timeline for no reason.

Following Up

If you haven't been paid by the due date, send a polite reminder the next working day. Reference the invoice number and amount. Keep it brief and professional. Most late payments are administrative oversights rather than deliberate avoidance, and a prompt, friendly nudge usually does the job.

If payment is still outstanding a week later, follow up by phone. A two-minute call often resolves what three emails could not.

Tools That Help

Typing invoices from scratch in Word or Google Docs works, but it's slow and error-prone. Invoicing software handles the formatting, numbering, and PDF generation automatically. Some tools also send automated reminders before and after the due date, which means you get paid faster without having to think about it.