The short answer
- Every invoice needs: a unique invoice number in sequence, the invoice date and the date of supply, your details and your client’s details, a clear description of what you’re charging for, amounts (and tax if you charge it), the total due and the payment terms.
- Make the due date explicit. “Payment within 30 days of the invoice date” is clearer than “30 days”.
- If you’re VAT-registered in the UK, extra details are required, including your VAT number.
- Keep copies: in the UK, six years for companies; in the US, the IRS asks for three to seven years depending on the case.
- Send the invoice as soon as the work is done, and follow up the day after the due date.
What an invoice is for
An invoice is three things at once: a request for payment, a record of the sale and an accounting document. It’s what your client’s accounts team needs to pay you, and what you need to track your income and file your taxes.
Getting it right matters for cash flow: the UK’s Small Business Commissioner estimated in March 2026 that late payments cost the UK economy almost £11 billion a year and cause 38 business closures a day.
Don’t confuse an invoice with:
- a quote or estimate, which proposes a price before the work;
- a proforma invoice, which presents an offer or supports formalities such as customs, but isn’t a demand for payment;
- a receipt, which proves a payment was made.
What to include on an invoice
| Description | Qty | Unit price | Total |
|---|---|---|---|
| Logo design and brand guide | 1 | £850.00 | £850.00 |
| Menu layout, two rounds of revisions | 6 h | £55.00 | £330.00 |
VAT reg. no. GB 123 4567 89. Payment by bank transfer within 30 days of the invoice date. Please quote the invoice number as your reference.
- A unique invoice number that follows on from the previous one.
- The invoice date, the date of supply, and a clear due date.
- Your business name, address and contact details (sole traders: an address where legal documents can be delivered).
- Your client’s name and address.
- A clear description of each item, with quantity and price.
- Subtotal, tax (if you charge it) and total due.
- How and when to pay.
Depending on your situation, you may also need:
- In the UK, if you’re VAT-registered: your VAT registration number, the time of supply (tax point), the VAT rate and amount for each rate, and the total excluding VAT. Issue the VAT invoice within 30 days of the tax point. For supplies of £250 or less including VAT, a simplified invoice is allowed. If you invoice in another currency, the VAT total must still be shown in sterling.
- If you’re a limited company: your company name as registered, and it’s good practice to show your company number and registered office.
- In the US: there’s no single federal format. Show sales tax separately (rules vary by state; Alaska, Delaware, Montana, New Hampshire and Oregon have no statewide sales tax). Put your EIN rather than your Social Security number on invoices. Business clients will often ask for a W-9, and may send you a Form 1099-NEC if they pay you $2,000 or more in a year (the threshold for payments made from 2026). Common terms are “Net 15” or “Net 30”.
- For international clients: the currency, and your bank details for international transfers.
Invoice numbering: the rule you can’t break
Each invoice needs a unique number, and numbers should follow one continuous sequence. No gaps, no duplicates, no going backwards. You can pick the format (INV-2026-042, 042, 26-09-042), but keep it once you’ve chosen.
If an invoice contains a mistake, don’t delete or edit it after sending: issue a credit note that cancels it, then a new, correct invoice.
Payment terms and late payment
State your payment terms clearly on every invoice: how many days the client has, and how to pay.
- Common terms: “due on receipt”, 14 days, 30 days.
- UK business-to-business: if nothing else was agreed, payment is due 30 days after the client receives the invoice or the goods/services, whichever is later. Agreed terms are usually capped at 60 days between businesses. You can then claim statutory interest of 8% above the Bank of England base rate, plus fixed compensation of £40 (debts under £1,000), £70 (£1,000 to £9,999.99) or £100 (£10,000 or more). Worked example: the £1,416 invoice above paid 30 days late, with the base rate at 3.75%, earns about £13.70 of interest plus £70 of compensation. A government bill introduced in May 2026 proposes to make 60 days a firm cap; check its progress before relying on it.
- With private individuals: be clear about the due date and payment method, and send a polite reminder the day after the due date.
How to write an invoice, step by step
- 1Your detailsBusiness name, address, contact, and VAT or tax number if you have one.
- 2Your clientName or company name and address.
- 3The numberThe next one in your sequence, no gaps or duplicates.
- 4The detailsEach item or service, quantity and unit price.
- 5The totalsSubtotal, tax at each rate, total due.
- 6The termsDue date, payment method, reference to quote.
Mistakes that delay payment
- A vague description. “Services” isn’t enough. Describe what was done, when and how much.
- No due date. Without a date, nothing is ever late, so you have no basis to chase.
- Invoicing late. Send the invoice as soon as the work is delivered.
- Never following up. Schedule a short reminder for the day after the due date; every day without one lets the delay grow.
- Mixing personal and business accounts. A dedicated business account makes it easy to see who has paid.
Invoice Harbour Café: logo and brand guide £850, plus 6 hours of menu layout at £55, VAT 20%
Ready: invoice INV-2026-042 for Harbour Café Ltd, £1,416 including VAT. Save it? You can then send it as a link, on WhatsApp or by email.
Your binôme prepares the invoice; you check it, then send it.
Try Binome360 for freeQuote first, invoice second
For bigger jobs, start with a quote. Once the client accepts, it becomes an invoice with the same lines, and you have a signed price to point to if there’s a dispute.
Invoice template you can copy
INVOICE No. [INV-2026-042]
Invoice date: [DD Mon YYYY] Date of supply: [DD Mon YYYY]
[Your business name] · [Address] · [Email / phone]
[VAT reg. no. / EIN, if applicable]
Bill to: [Client name] · [Address]
Description Qty Unit price Amount
[Service or product] [1] [0.00] [0.00]
Subtotal: [0.00]
Tax [rate]: [0.00]
Total due: [0.00]
Due date: [DD Mon YYYY] · Pay by [bank transfer: sort code / account no. or IBAN]
Please quote the invoice number as your payment reference.
Say what you’re charging for. Your binôme prepares the document; you check it and send it.
- Automatic numbering, with no gaps or duplicates
- Your details and legal notes in the footer
- Four templates in your colours, downloadable as PDF
- A link to share on WhatsApp or email: clients can accept a quote online
- An accepted quote becomes an invoice in one tap; late invoices are flagged
A note on e-invoicing: some countries now require structured electronic invoices between businesses through approved platforms (France is phasing this in from September 2026, for example). Binome360 produces clear quotes and invoices, but it isn’t a certified e-invoicing platform. If that obligation applies to you, use an approved provider and check with your accountant.
Frequently asked questions
Do I need a registered business to send an invoice?
No. Sole traders and freelancers invoice under their own name all the time. In the UK you do need to register for Self Assessment once your gross trading income goes over the £1,000 trading allowance in a tax year, and since April 2026 sole traders with qualifying income over £50,000 must keep digital records under Making Tax Digital. Check the equivalent rules in your own country.
Can I write an invoice by hand?
Yes, a handwritten invoice is valid as long as it has all the required details and follows your numbering sequence. But it’s harder to store, find and copy, and it won’t meet e-invoicing requirements where they apply. A digital tool also removes calculation mistakes.
What if a client doesn’t pay?
Go step by step. A friendly reminder the day after the due date, then a second one a week later that mentions late-payment interest. If nothing happens, send a formal final demand letter giving a clear deadline. As a last resort, in England and Wales you can start a small claim online through Money Claim Online; other countries have similar small-claims procedures.
What’s the difference between an invoice and a receipt?
An invoice asks for payment and details the sale. A receipt proves the payment was made. You can mark an invoice as “Paid”, with the date and payment method, so it also serves as proof of payment.
Can I invoice in a foreign currency?
Yes, you can invoice in the currency agreed with your client. If you’re VAT-registered in the UK and invoice in another currency, you still need to show the VAT amount in sterling. When in doubt about international sales, ask your accountant.
In short
A good invoice has a unique number in an unbroken sequence, clearly identifies you and your client, describes each item with its amount, and states the due date and how to pay. Send it early, follow up promptly, keep your records, and check the extra rules if you’re registered for VAT or sales tax.
Sources
- GOV.UK, “Invoicing and taking payment from customers”: gov.uk/invoicing-and-taking-payment-from-customers.
- GOV.UK, “Late commercial payments: charging interest and debt recovery”: gov.uk/late-commercial-payments-interest-debt-recovery.
- HMRC, VAT Notice 700/21 “Keeping VAT records” and guidance on VAT invoices.
- IRS, “How long should I keep records?”: irs.gov/businesses/small-businesses-self-employed/how-long-should-i-keep-records.
- HMRC, VAT Notice 700/21 “Keeping VAT records” (sections 4.1 and 4.5) and VAT Notice 700 (section 16.4).
- Office of the Small Business Commissioner, late payment figures, March 2026: smallbusinesscommissioner.gov.uk.
- GOV.UK, “Making Tax Digital for Income Tax”.
Also available in Français.