Money
How to write an invoice (+ exactly what it must include)
Your first invoice shouldn’t be intimidating. It’s a short document that says who owes what, for what, and by when. Here’s exactly what goes on it — and how to make sure it gets paid.
What every invoice must include
In the UK, an invoice should clearly show:
- The word “Invoice” (so it’s unambiguous)
- A unique invoice number (see below)
- Your name / business name and address
- The client’s name and address
- The date of the invoice
- A description of what you’re charging for
- The amount for each line, and the total due
- The payment due date and how to pay (your bank details)
If you’re VAT-registered, you also need your VAT number, the VAT rate, and the VAT amount. If you’re not, you don’t mention VAT at all.
How to number invoices
Invoice numbers must be unique and sequential — no gaps, no duplicates. A simple, professional format is INV-2026-001, then -002, and so on. This matters for your bookkeeping and looks credible to clients.
The bit that actually gets you paid
A correct invoice is table stakes. Getting paid on time is about a few small habits:
- Send it immediately — the day the work is done, not at month-end.
- Set a clear due date — “within 14 days” beats “on receipt”.
- Make paying easy — put your bank details right on it; better still, a pay link.
- Chase politely but promptly — a friendly nudge the day after it’s due works.
Don’t do this by hand every time
Writing invoices in Word and tracking them in your head is how you end up with unpaid invoices you forgot about. Sedonis handles invoicing properly: professional templates, automatic sequential numbering, one-tap duplicate for repeat clients, and a clear view of what’s paid, unpaid and overdue — so nothing slips. It’s free to start.
Just registered your business? Here’s how to set up a limited company, and the honest take on sole trader vs limited company.
General information, not tax advice. If you’re VAT-registered or unsure, check GOV.UK or an accountant.