How to Write an Invoice in the UK: Complete 2026 Guide

How to Write a Professional Invoice in the UK

Writing your first invoice can feel daunting, but it doesn't have to be. Whether you're a freelancer, sole trader, or contractor, this guide walks you through every step of creating a professional invoice that gets you paid on time.

What You Need Before You Start

Before creating your invoice, make sure you have the following information ready:

• Your full business name and address
• Your client's full name/company name and address
• A unique invoice number (sequential is best)
• The date you're issuing the invoice
• A clear description of services or goods provided
• The total amount due in GBP (£)
• Your payment terms (e.g., Net 14, Net 30)
• Your bank details or preferred payment method

Step 1: Add Your Business Details

At the top of your invoice, include your full business name, trading address, phone number, and email. If you're a sole trader operating under your own name, use your full legal name. If you have a registered business name, use that instead.

Step 2: Add Your Client's Details

Include your client's full name or company name, their registered address, and a contact email. This helps avoid any confusion about who the invoice is addressed to and creates a clear paper trail.

Step 3: Include an Invoice Number and Date

Every invoice needs a unique, sequential invoice number. This is an HMRC requirement and helps both you and your client track payments. Start with INV-001 and work upwards. Never reuse or skip numbers. Also include the date you're issuing the invoice.

Step 4: Describe Your Services

Be specific about what you're charging for. Instead of writing "consulting services", write "Website strategy consultation — 3 hours @ £75/hr". This reduces disputes and helps your client understand exactly what they're paying for.

Step 5: Calculate the Total

List each line item with its individual cost, then show the subtotal. If you're VAT registered, add the VAT amount (usually 20%) and show the grand total. If you're not VAT registered, simply show the total and do NOT include a VAT line.

Step 6: Add Payment Details

Tell your client how to pay you. Include your bank name, sort code, and account number for bank transfers. Specify your payment terms clearly — "Payment due within 14 days" is standard for freelancers. You can also mention late payment fees if applicable.

Common Mistakes to Avoid

• Forgetting to include a unique invoice number
• Not specifying payment terms
• Including VAT when you're not VAT registered
• Using vague descriptions like "work completed"
• Sending the invoice to the wrong email address

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