How to Write an Invoice in the UK: Complete Step-by-Step Guide
Master the art of professional invoicing with this comprehensive guide for UK freelancers and small businesses.
Whether you're issuing your first invoice or the thousandth, getting it right matters. A well-written invoice helps you get paid faster, looks professional, and keeps you compliant with UK tax law.
Step 1: Choose Your Invoice Format
You have three main options for creating invoices:
📄 Word/PDF Template
Free but time-consuming. Requires manual updates and tracking.
📊 Spreadsheet
More flexible than Word. Still requires manual invoice numbering.
💻 Invoicing Software
Automated, professional, and tracks everything. Recommended.
Step 2: Add Your Business Details
Start with your information at the top of the invoice. This is legally required and helps clients identify you.
Include:
- ✓ Your full legal business name
- ✓ Business address
- ✓ Contact email and phone (recommended)
- ✓ VAT number (if registered)
- ✓ Company registration number (if limited company)
Step 3: Add Client Details
Include your client's information so there's no confusion about who the invoice is for.
Bill To:
Client Company Ltd
123 Client Street
London, EC1A 1BB
Step 4: Create a Unique Invoice Number
Every invoice must have a unique, sequential number. This is a legal requirement in the UK.
✅ Good Examples:
- • INV-000001, INV-000002, INV-000003
- • 2026-001, 2026-002, 2026-003
- • JAN-001, JAN-002, JAN-003
❌ Avoid:
- • Skipping numbers (INV-001, INV-003)
- • Reusing old numbers
- • Random numbers with no sequence
Step 5: Add the Date
Include the date you're issuing the invoice. This starts the payment terms countdown. Use a clear format like "25 January 2026" or "25/01/2026".
Step 6: Describe the Work
This is the most important section. Be specific about what you're charging for.
❌ Too Vague:
"Services rendered"
"Consulting work"
"Project fee"
✅ Clear & Specific:
"Website design: Homepage and About page"
"SEO consultation - Keyword research and strategy"
"Logo design with 3 revisions"
Step 7: Add Line Items (If Applicable)
Break down your charges into individual line items. Each line should show:
| Description | Qty | Rate | Amount |
|---|---|---|---|
| Website Development | 40 hrs | £50.00 | £2,000.00 |
| Logo Design | 1 | £300.00 | £300.00 |
| Total | £2,300.00 | ||
Step 8: Calculate VAT (If Registered)
If you're VAT registered, show the breakdown clearly:
Subtotal: £2,000.00
VAT (20%): £400.00
Total: £2,400.00
Step 9: Set Payment Terms
Clearly state when payment is due. Common UK payment terms:
Net 7
Payment due within 7 days
Net 14
Payment due within 14 days
Net 30
Most common for businesses
Pro tip: Include a specific due date ("Payment due by 10 February 2026") rather than just "Net 14" to avoid confusion.
Step 10: Add Payment Instructions
Make it easy for clients to pay you. Include:
- ✓ Bank account details (name, sort code, account number)
- ✓ Payment reference (usually the invoice number)
- ✓ Alternative payment methods (PayPal, Stripe, etc.)
- ✓ Payment link (if using online invoicing software)
Optional: Terms & Conditions
Consider adding:
- • Late payment fees (e.g., "8% interest per annum on overdue amounts")
- • Dispute resolution process
- • Refund or cancellation policy
- • Liability limitations
Final Checklist Before Sending
✓ Double-check everything:
- □ Unique invoice number is correct and sequential
- □ Client details are accurate
- □ Descriptions are clear and specific
- □ All calculations are correct (especially VAT)
- □ Payment terms and due date are clear
- □ Bank details or payment link included
- □ No spelling or grammar errors
The Easier Way: Use Professional Software
Creating invoices manually is time-consuming and error-prone. Professional invoicing software handles all the details automatically.
Experi: Create Perfect Invoices in 60 Seconds
Stop worrying about what to include. Experi's intelligent templates guide you through every step and ensure nothing is missed.
- ✓ Automatic sequential numbering
- ✓ Pre-filled business and client details
- ✓ Built-in VAT calculator
- ✓ Professional PDF generation
- ✓ Send invoices directly from the platform
- ✓ Track when clients open and pay
Multi-Currency Support
Invoice international clients in GBP, USD, EUR, and 30+ currencies
Key Takeaways
- ✓ Always use a unique, sequential invoice number
- ✓ Be specific in your work descriptions
- ✓ Include clear payment terms and due dates
- ✓ Make it easy to pay with bank details or payment links
- ✓ Double-check VAT calculations if registered
- ✓ Send invoices promptly after completing work
- ✓ Keep copies of all invoices for at least 6 years
Ready to create your first invoice?
Experi makes invoicing effortless. Focus on your work, not paperwork.
Start Creating Invoices Free