Self-Employed Invoicing Guide UK 2026: How to Invoice Properly

Getting invoicing right is one of the most important things you can do as a self-employed person. A proper invoice isn't just a payment request — it's a legal document, a tax record, and often the first impression a client has of how professional you are.

This guide covers everything: what the law requires, what best practice looks like, and the practical tricks that actually get you paid faster.

What Must a UK Invoice Include?

There's no single "invoice law" in the UK, but several regulations combine to create requirements. Here's the minimum for a sole trader invoice:

Legally Required

• The word "Invoice" — clearly displayed at the top
• Your name and address (or business name and registered address)
• Client's name and address
• A unique invoice number — sequential, no gaps (see our numbering system guide)
• Invoice date
• Description of goods or services
• Amount(s) due
• Total amount
• VAT amount and your VAT number (only if VAT-registered)

Best Practice (Highly Recommended)

• Payment due date — not just "Net 30" but the actual calendar date
• Payment methods accepted — bank transfer details, PayPal, etc.
• Your bank details — sort code and account number for BACS payments
• Purchase order number — if the client provided one
• Late payment terms — reference to your late payment policy
• Project or job reference

Invoice Format: Digital vs Paper

There's no legal requirement for a specific format. You can send invoices as:

• PDF attached to email — most common, most professional
• Online invoice — via invoicing software with a payment link
• Paper — still valid but slow and easily lost

We recommend PDF for most freelancers. Use our free invoice generator to create professional PDFs in seconds.

Payment Terms: What to Set

The payment terms you choose directly affect your cash flow. Here's what works:

Term	Meaning	Best For
Due on receipt	Pay immediately	Small one-off jobs, new clients
Net 7	Pay within 7 days	Regular small clients
Net 14	Pay within 14 days	Standard freelance work
Net 30	Pay within 30 days	Corporate clients, larger projects
Net 60	Pay within 60 days	Avoid if possible

Read our full payment terms comparison for more detail. Shorter is always better for your cash flow.

VAT on Invoices

If you're not VAT-registered (turnover under £85,000), you don't charge VAT and don't need a VAT number on your invoices. Simple.

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

• Your VAT registration number
• The VAT rate applied to each item
• The VAT amount
• The total excluding VAT
• The total including VAT

See our VAT registration guide for when you need to register.

International Invoicing

Invoicing clients outside the UK has extra considerations:

• Currency: You can invoice in any currency. Record the GBP equivalent for your tax records using the exchange rate on the invoice date.
• VAT: Services to non-UK businesses are usually zero-rated (no VAT charged). The "place of supply" rules determine this.
• Payment method: Consider Wise (formerly TransferWise) for better exchange rates than bank transfers.
• Language: Invoice in English but include the client's language if helpful.

Our international invoicing guide covers this in full detail.

How to Get Paid Faster

The invoice itself is only half the battle. Here's what actually speeds up payment:

1. Invoice Immediately

Don't wait until month-end. Send the invoice the day the work is complete (or the milestone is reached). Every day you delay is a day added to your wait.

2. Make Payment Easy

Include your bank details directly on the invoice. Better yet, include a payment link. The fewer steps between "I should pay this" and "it's paid," the faster you get paid.

3. Use Shorter Payment Terms

Net 14 gets paid faster than Net 30. And "Due on receipt" works better than you'd think — especially for smaller amounts.

4. Take Deposits

For larger projects, take 25-50% upfront before starting work. This protects your cash flow and tests the client's ability to pay. See our deposit policy guide.

5. Follow Up Promptly

Send a polite reminder the day after the due date. Don't wait a week. Our reminder email templates make this painless.

6. Charge Late Fees

UK law gives you the right to charge statutory interest on overdue invoices (8% + Bank of England base rate). Mention this on your invoices — even if you never actually charge it, the deterrent effect is real.

Invoicing Software vs Templates

You have two main options:

Invoice Templates (Free/Cheap)

• ✅ No monthly cost
• ✅ Full control over design
• ✅ Simple for low invoice volumes
• ❌ Manual tracking of paid/unpaid
• ❌ No automatic reminders
• ❌ Numbering and record-keeping is on you

Use our free invoice generator or download our invoice template.

Invoicing Software (£0-30/month)

• ✅ Automatic invoice numbering
• ✅ Payment tracking and reminders
• ✅ Online payment links
• ✅ Tax reports and MTD integration
• ❌ Monthly cost
• ❌ Learning curve

See our best invoicing software comparison for recommendations.

Record Keeping Requirements

HMRC requires you to keep invoicing records for at least 5 years after the 31 January submission deadline. This includes:

• Copies of all invoices you sent
• Copies of all invoices you received (expenses)
• Bank statements showing payments in and out
• A record of which invoices have been paid and which are outstanding

With Making Tax Digital rolling out from April 2026, digital record-keeping is becoming mandatory. Get into the habit now.

When Clients Don't Pay

Even with perfect invoices, some clients won't pay on time. Your escalation path:

1. Polite reminder emails (day 1-14 overdue)
2. Formal chasing (day 14-30)
3. Letter before action (day 30-45)
4. Small claims court (last resort)