You did the work. The client is happy. Now comes the part nobody enjoys: the invoice.
Invoicing feels like admin, but it is really a sales document — it is the last thing standing between you and getting paid. A clear, professional invoice with sensible terms gets paid faster. A vague one gets “just checking this” emails, delays, and awkward chases. Here is how to invoice properly as a UK freelancer or tradesperson, plus a free tool that does the formatting for you.
What every UK invoice needs
Before anything else, the basics. A UK invoice should show:
- A unique invoice number — sequential, never repeated.
- Your business name and address.
- Your client’s name and address.
- A clear description of the goods or services supplied.
- The supply date (when the work was done) and the invoice date.
- The amount being charged, broken down by line item.
- VAT details and your VAT number, if you are VAT-registered.
If you are not VAT-registered, you simply leave VAT off — but the rest still applies. Keep copies of every invoice you send for at least six years; HMRC expects it.
Number your invoices like you mean it
Pick a system and never deviate: INV-0001, INV-0002, and so on works perfectly. The rules are simple — every number unique, no gaps you cannot explain, and no reusing a number when a client asks for a correction (issue a new invoice or a credit note instead).
Why does this matter? Two reasons. First, when a client emails “which invoice was the bathroom one?”, a clean sequence answers in seconds. Second, your accountant will love you at year end, and HMRC will have no questions about missing numbers.
Set payment terms before you need them
The single biggest invoicing mistake freelancers make is sending an invoice with no due date. “Payment due on receipt” sounds firm but confuses people; no terms at all means the client pays whenever they feel like it.
Pick your terms and put them on every invoice:
- 14 days is common for freelancers and keeps cash flowing.
- 30 days is standard in many industries — clients expect it.
- 50% upfront for larger projects protects you from doing weeks of work for nothing.
State the terms plainly on the invoice: “Payment due within 14 days of invoice date.” If you want to be paid by bank transfer, include your bank details or payment link on the invoice itself — every extra step a client has to take is a reason to pay tomorrow instead of today.
Make the invoice itself do the work
The invoice is a reflection of your business. A Word document with a stretched logo and dodgy formatting tells the client “admin is chaos here” — not the message you want when you are asking for money.
A professional invoice has your logo, consistent formatting, clearly separated line items with quantities and rates, and a single obvious total. It should look like it came from a business that has its act together, because that is a business clients pay promptly.
This is exactly why we built our free Invoice Generator. You type in your details, add your line items, and it builds a clean, professional invoice in your browser — VAT calculations, logo, invoice numbering, the lot. One click downloads or prints it as a PDF. No account, no cost, and your data never leaves your computer.
Try it here: https://altuswebsolutions.com/tools/invoice-generator/
Chasing late payers without the awkwardness
Even perfect invoices sometimes go unpaid. Here is a calm, professional sequence that works:
- The day after the due date, send a short, friendly nudge: “Just checking you received invoice INV-0007 — let me know if anything needs clarifying.” Most late payments are forgetfulness, not malice.
- A week later, be firmer: restate the amount, the due date, and ask for a payment date.
- Two to three weeks overdue, pick up the phone. A call resolves in five minutes what email cannot in five days.
And know your rights: under UK law, if your terms do not say otherwise, you can charge statutory interest on late commercial payments — 8% over the Bank of England base rate — plus fixed compensation per invoice. You rarely need to use it; mentioning your terms is usually enough.
Keep it boring, keep it paid
Invoicing will never be the fun part of running your business. But a five-minute habit — unique number, clear description, stated terms, professional layout, sent the same day the work finishes — is the difference between cash flow and cash chase.
Do it properly from the first invoice and it stays easy forever. Our free tool handles the formatting; the rest is just discipline.
Generate your first invoice now: https://altuswebsolutions.com/tools/invoice-generator/
Frequently asked questions
What must legally be on a UK invoice?
A unique invoice number, your business name and address, your customer’s name and address, a description of the goods or services, the supply date, the invoice date, the amount charged, and — if you are VAT-registered — VAT details and your VAT number.
How long should I give clients to pay?
Fourteen days is typical for freelancers; 30 days is common in many industries. Whatever you choose, write it on every invoice so there is no ambiguity.
Can I charge interest on late payments?
Yes. Under the Late Payment of Commercial Debts (Interest) Act 1998, you can charge statutory interest of 8% over the Bank of England base rate on overdue commercial invoices, plus fixed compensation — unless your contract sets different terms.
Is the Altus invoice generator free for business use?
Yes — free, unlimited, no account and no watermark. It runs entirely in your browser, so your business and client details never leave your computer.
Want a website that brings you clients who pay on time? Book a free 15-minute consultation or email [email protected].
