How to Send an Invoice in the UK — A Complete Guide (2026)
Sending an invoice correctly is one of the most important skills for any UK freelancer or small business. Get it right and you get paid faster. Get it wrong and you're chasing payments and damaging client relationships.
This guide covers everything: what to include, how to deliver your invoice, payment terms, and what to do if a client doesn't pay.
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Step 1: Create a Professional Invoice
Before you can send an invoice, you need one. Every UK invoice should include:
- Your name and address (full legal name or business name)
- Your client's name and address
- A unique invoice number (e.g. INV-001, INV-002)
- Invoice date — when it was created
- Payment due date — your payment terms
- A description of the work — be specific
- Itemised costs — unit price and quantities
- Subtotal, VAT (if applicable), and total
- Your payment details — bank account number and sort code (or PayPal, Stripe, etc.)
If you're VAT registered, also include your VAT registration number and show VAT separately.
Step 2: Choose the Right File Format
Most clients expect invoices as a PDF. This ensures:
- The formatting stays consistent
- It can't be accidentally edited
- It can be opened on any device
- It's easy to attach to email
Avoid sending Word documents or spreadsheets — they look unprofessional and can cause formatting issues.
Use Billdrop to create a professional-looking PDF invoice in minutes — no design skills needed.
Step 3: How to Deliver Your Invoice
Option 1: Email (most common)
Email is the standard method for UK freelancers and businesses. When emailing an invoice:
- Subject line: "Invoice [Number] — [Your Name/Business] — [Brief Description]"
Example: "Invoice INV-047 — Jane Smith Design — Website Redesign" - Attach the invoice PDF
- Include a short covering note:
Hi [Client Name],
Please find attached Invoice INV-047 for the website redesign project, totalling £1,200.00.
Payment is due by [date]. Please transfer to [bank account details] or pay via the link below.
Let me know if you have any questions.
Best,
[Your Name]
Option 2: Accounting Software (Xero, FreeAgent, etc.)
If you use accounting software, you can send invoices directly from the platform. This also helps with record-keeping and chasing overdue payments.
Option 3: Post
Rare in 2026, but still used for some industries or clients. Send by recorded delivery if you need proof of receipt.
Step 4: Set Clear Payment Terms
Your payment terms should be stated clearly on the invoice and in any contract or SOW:
- 30 days — standard for UK B2B invoicing
- 14 days — common for smaller amounts or freelance work
- Due on receipt — for very small or one-off amounts
Always state the exact due date, not just "30 days" — this avoids confusion. For example: "Payment due by 6 May 2026."
Step 5: Accept Payment
Make it as easy as possible for clients to pay you. Popular options:
- BACS / Bank transfer — most common in UK B2B. Include account number and sort code.
- PayPal — good for international or smaller clients
- Stripe — professional payment link, clients can pay by card
- Cheque — almost obsolete but still used in some industries
The easier you make it, the faster you get paid.
Step 6: Record the Invoice
Keep a record of every invoice you send. You need this for:
- Tax returns — HMRC requires you to keep invoicing records for at least 6 years
- Chasing overdue payments
- VAT returns (if VAT registered)
Use a spreadsheet, accounting software, or Billdrop's invoice history to track invoices.
Step 7: Follow Up If Not Paid
Most clients pay on time, but some need a nudge. Here's a simple escalation process:
Day 1 (due date): Check if payment has been received. If not, send a polite reminder.
Day 7: Send a follow-up email referencing the original invoice.
Day 14: More formal email, mention statutory interest.
Day 30+: Consider a formal letter before action or a debt recovery service.
Under the Late Payment of Commercial Debts Act 1998, you're entitled to charge:
- Statutory interest at 8% above the Bank of England base rate
- A fixed compensation fee (£40, £70, or £100 depending on the debt amount)
Frequently Asked Questions
When should I send an invoice?
For project work: on delivery. For ongoing services: monthly, or at the agreed schedule. For large projects: consider milestone billing with deposits.
What if I don't have a business bank account?
You can use your personal account — just make sure it's clearly labelled. Having a separate business account makes bookkeeping much easier.
Can I send invoices by text or WhatsApp?
Technically yes, but it's unprofessional and makes record-keeping harder. Always use email with a PDF attachment.
Do I need a contract before invoicing?
A contract isn't legally required, but it's strongly recommended. An agreed contract makes chasing payment much easier.
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Billdrop is a free invoice generator for UK freelancers and small businesses. Create and download professional PDF invoices in minutes.