Most late payments are not clients being difficult. They are invoices that were vague, arrived late, went to the wrong person, or gave the payer nothing to act on. Learning how to write an invoice properly is unglamorous and it is the difference between being paid in two weeks and chasing for two months. Our printable invoice and receipt set covers the format so you are not rebuilding one each time.
Invoicing something today? Grab the invoice set, and before you send it, check the two things at the end of this piece — the due date and the recipient. Those two cause most of the delays.
Shop Small Business Paper Kit — Editable Invoice, Price List, Gift Certificate, Thank You Cards & Voucher Templates for Google Slides & Canva →What Must Be On It
In the UK, an invoice needs all of the following. This is not stylistic — it is what makes the document an invoice rather than a request.
- The word "Invoice", clearly. Not "statement", not "summary".
- A unique invoice number, sequential.
- Your name, trading name and address.
- The client's name and address — the legal entity, not just a contact.
- The date of issue, and the date the work was supplied if different.
- A clear description of what you supplied.
- The amount due, and how it is made up.
- Payment terms and the due date.
- How to pay — bank name, sort code, account number, reference.
If you are VAT registered there are additional requirements, including your VAT number and the rate and amount charged. If you are not registered, do not put anything resembling VAT on the invoice at all.
Numbering, done simply
Sequential and unique is the whole rule. 2026-001 upwards is plenty. Two things to avoid: never reuse a number, and never skip one because an invoice was cancelled — issue a credit note instead. An accountant looking at a gap in your numbering will always ask, and "I cancelled it" is a much better answer when there is a credit note behind it.
The Wording That Gets You Paid Sooner
Small changes, disproportionate effect.
| Instead of | Write |
|---|---|
| "Payment terms: net 14" | "Due by Friday 12 September 2026" |
| "Consultancy services" | "Brand workshop, 4 Sept, as agreed 20 Aug" |
| "Please pay at your convenience" | "Payment due by [date]. Bank details below." |
| "Thanks!" | "Thank you — please use reference INV-2026-014." |
The date one matters most. "Net 14" requires the payer to do arithmetic; a date does not. An invoice with a specific due date lands in a diary; one with a term lands in a pile.
The description matters more than people expect too. A finance team paying an invoice for "consultancy services" often cannot tell which project or budget it belongs to, so it goes back to someone for approval — and that is a fortnight gone. Naming the work, the date and who agreed it means it can be paid without a conversation.
Shop Small Business Bookkeeping →Send It Immediately, and to the Right Person
Two habits fix most delays.
Invoice the day you finish. Not the end of the month, not when you next do admin. An invoice arriving with the work feels part of the job; one arriving three weeks later feels like a separate event, and it will miss the payment run it should have caught.
Find out who actually pays. Your day-to-day contact is frequently not the person who processes invoices, and an invoice sitting in their inbox is invisible to accounts. Ask once, at the start: "who should invoices go to, and is there a PO number or reference you need on them?" That single question prevents more late payments than any amount of chasing.
Ask about payment runs
Larger clients often pay on fixed dates — the last Friday of the month, say. Knowing that means an invoice sent on the 26th waits five weeks while one sent on the 20th waits one. It costs nothing to ask.
Chasing, Without Damaging the Relationship
Assume administrative error, not bad faith. It usually is.
- Day after due: short and friendly. "Just checking this reached the right place — happy to resend." Gives them an easy out.
- A week later: firmer, still polite. Restate the amount, the date it was due and the reference.
- Two weeks: phone the accounts contact. Email is easy to leave; a call rarely is.
- Beyond that: a formal notice mentioning statutory late-payment terms.
In the UK you have a statutory right to claim interest and a fixed sum on late commercial payments. In practice, mentioning that the terms exist resolves far more invoices than actually invoking them — and invoking them is a decision about whether you want the client again.
One quiet piece of advice: chase every time, even when it feels awkward. Clients who learn that you do not chase are the ones who pay you last. This is general guidance rather than legal advice; for a debt that is genuinely disputed or very large, take proper advice.
Keep the Record Straight
An invoice is also a bookkeeping entry. Log it when you send it, not when it is paid, so you can see what is outstanding at a glance — that list is the single most useful number in a small business.
The small business bookkeeping set and the profit dashboard handle income and expenses together, and the freelancer budget and tax vault covers setting tax aside as payments land — our guide to self assessment record keeping explains what to keep and for how long. For the rest of the paperwork a small business sends out, the small business paper kit covers price lists, gift certificates and thank-you cards in the same style, so everything a client receives looks like it came from one place.
Shop Freelancer Budget & Tax Vault, Google Sheets Template for Self-Employed, Irregular Income Planner, Tax Set-Aside Tracker →Deposits, and Not Being Owed Money in the First Place
The most effective invoicing improvement is not an invoicing change at all — it is being owed less. Three things worth putting in place before the work starts.
Take a deposit on anything substantial. Somewhere between 25% and 50% up front is normal across most trades and services, and it is not rude to ask. A client unwilling to pay a deposit is telling you something useful very cheaply.
Agree the price in writing. Not a contract necessarily — an email saying "to confirm: X of work, £Y, invoiced on completion, 14 days" is enough to prevent almost every payment dispute. Most disagreements are about what was agreed, not about willingness to pay.
Invoice in stages on longer jobs. Monthly or by milestone, rather than one large invoice at the end. It halves your exposure, smooths your own cash flow, and clients generally prefer it too.
When to stop working
An uncomfortable one, and worth deciding in advance rather than in the moment: if an invoice is significantly overdue and the client wants more work, it is entirely reasonable to pause until it is settled. Say it plainly and without apology — "I will pick this up as soon as invoice 014 clears." Continuing to work while unpaid is how a small debt becomes a large one.
Invoicing FAQs
What must be on an invoice in the UK?
The word 'invoice', a unique invoice number, your name and address, the client's name and address, the date, a description of what you supplied, the amount due and the payment terms. If you are VAT registered there are additional requirements.
Do sole traders need to number invoices?
Yes, and they must be unique and sequential. It is how you and HMRC can tell that none are missing, and it is the first thing an accountant asks for.
What payment terms should I use?
Fourteen days is common for small suppliers and thirty is standard for larger clients. Whatever you choose, put an actual due date on the invoice rather than only 'net 14' — a date gets paid faster than a term.
How soon should I send an invoice?
The same day you finish, or the day the work is delivered. Invoices sent a fortnight later feel less urgent to the payer and are far more likely to slip a payment run.
How do I chase a late payment?
A short, friendly email the day after it is due, then a firmer one a week later, then a phone call. Most late payments are administrative rather than deliberate, and the first nudge usually resolves it.
Can I charge interest on late payments?
In the UK, businesses have a statutory right to claim interest and a fixed sum for late commercial payments. Mentioning that the terms exist is usually more effective than actually invoking them.
Send a better one today. The invoice and receipt set is editable and numbered, or browse the full Small Business collection.