Hand-written invoices on a scrap of paper. An amount texted with no breakdown. A WhatsApp message saying "that'll be £350 cheers." If you've done any of these, you're not alone — but you are leaving money on the table.
A professional invoice isn't about looking fancy. It's about getting paid faster, avoiding disputes, and keeping HMRC happy. Here's how to get it right.
What Every Invoice Must Include
At a minimum, your invoice needs:
Your business name and contact details. Full name (or trading name), address, phone number, email. If you're VAT registered, your VAT number goes here too.
The customer's name and address. Not just "Dave" — their full name and the property address where the work was done. This matters for their records and yours.
A unique invoice number. Sequential is easiest: INV-001, INV-002, and so on. This is an HMRC requirement for record-keeping. It also makes it much easier to reference when chasing payments — "just following up on invoice 247" is clearer than "that job I did at your house."
The date. Both the date of the invoice and the date the work was carried out. If they're different dates, include both.
A clear description of the work. Itemised is best. Not "plumbing work — £400" but:
Diagnose and repair leak to mains stopcock — £95
Replace corroded gate valve with full-bore lever valve — £45
Materials (valve, compression fittings, PTFE) — £28
Labour (2.5 hours @ £45/hr) — £112.50
Total: £280.50
Customers rarely query an itemised invoice. They can see exactly what they're paying for. Vague invoices invite questions and delays.
Payment terms. When do you expect payment? "Due on receipt" means now. "Net 14" means within 14 days. Be explicit. If you don't state payment terms, the customer can reasonably claim they didn't know when to pay.
Payment methods. Bank details, a payment link, or both. The easier you make it to pay, the faster you get paid.
What Makes an Invoice Look Professional
You don't need a graphic designer. You need three things: consistency, clarity, and your logo (if you've got one).
Use a template. Every invoicing app comes with templates. Pick one that's clean and simple. White background, your logo at the top, clear sections. Avoid anything too busy or colourful — you're a tradesperson, not a nightclub promoter.
Use the same template every time. Consistency builds trust. When a repeat customer gets an invoice that looks like the last one, it feels familiar and legitimate. If every invoice looks different, it feels amateurish.
PDF format. Always send invoices as PDFs, not photos of handwritten notes or plain text in a message. PDFs look professional, they're easy to store, and they can't be accidentally edited.
The Payment Link Difference
This single change will get you paid faster than anything else on this list. Include a clickable payment link in every invoice.
Stripe, PayPal, and most invoicing apps generate these automatically. The customer opens the invoice, taps the link, enters their card details or uses Apple Pay, and it's done. Thirty seconds. No bank transfers, no typing in sort codes, no "I'll do it when I'm at my computer."
Yes, you'll pay a small transaction fee — typically 1.4% + 20p for Stripe. On a £300 invoice, that's about £4.40. Worth every penny when you consider the alternative is waiting weeks for a bank transfer that might never come.
Timing: When to Send
Send the invoice the same day you finish the job. Ideally within an hour of leaving. The customer has just seen you work, they're satisfied with the result, and they're mentally prepared to pay.
Leave it a week and the dynamic changes. The job feels like it was ages ago. The urgency to pay disappears. And if something minor goes wrong in the meantime (a fitting drips, a switch feels loose), they'll hold off on payment until it's sorted — even if it's nothing to do with your work.
Tools That Make It Easy
QuickBooks — solid all-rounder, £10/month, good mobile app. Create and send invoices from your phone in under two minutes.
Xero — more powerful, from £15/month. Better if your accountant uses it. Automatic payment reminders are excellent.
Stripe Invoicing — pay per invoice (0.4% on paid invoices). No monthly fee. Good if you only send a few invoices a week.
Wave — completely free. Basic but effective for sole traders who don't need bells and whistles.
If you want to skip the faff entirely, AI tools like Gaffer let you send a voice note describing the job and it creates a professional invoice with a payment link automatically. You say "fitted a new shower valve and replaced two radiator valves at 14 Elm Street for Mrs Cooper, materials were £85, labour was three hours" and a proper itemised invoice goes out. No forms, no typing, no app to learn.
One Last Thing: Keep Copies of Everything
HMRC requires you to keep records of all invoices for at least five years (six if you're VAT registered). Digital copies are fine — you don't need to print anything.
Most invoicing apps store everything automatically. If you're using a manual template, save every PDF to a folder in Google Drive or Dropbox. One folder per tax year, one sub-folder per month. Takes seconds and saves hours when your accountant asks for your records.
A professional invoice takes two minutes to create and it's the difference between getting paid this week and chasing for months. Set up your template, include a payment link, and send it before you start the engine. Your cash flow will thank you.