What to put on an invoice so you get paid on time

An invoice that gets paid on time shows who is charging whom, what for, how much, and when and how to pay: your name and contact details, your customer's name, a unique invoice number, the date, an itemised description with quantities and prices, the total with any tax, the due date and the payment details. In the UK, a business that is registered for VAT must also show VAT details. In the US there is no single federal invoice format, but the list above is common practice.

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The UK: what the law asks for

HMRC's VAT Notice 700/21 sets out what a VAT invoice must show. A full VAT invoice needs:

• a sequential number that uniquely identifies the document
• the time of supply, and the date of issue if it is different
• your name, address and VAT registration number
• your customer's name and address
• a description of the goods or services, and the quantity
• the unit price, the VAT rate, and the amount payable excluding VAT
• the total payable excluding VAT, any cash discount rate, and the total VAT in sterling

For a sale of £250 or less including VAT, a simplified invoice is allowed. It needs your name, address and VAT number, a description, and for each VAT rate the total including VAT and the rate charged. Exempt supplies are left out. Above £250 you need a full VAT invoice or a modified invoice that shows VAT-inclusive values.

If you are not registered for VAT, you cannot charge VAT or show a VAT number. The invoice should still show your details, the description, the total and the payment terms.

The standard UK VAT rate is 20%, with 5% and 0% rates for some goods and services. Check the current rates on GOV.UK before you invoice.

The US: no single format

The United States has no federal invoice form. The IRS expects you to keep records that support your income, and invoices are among the supporting documents it lists in Publication 583. Sales tax is set by each state, so the tax line depends on where the sale is made and where the customer is.

In practice, US freelancers include the same fields as the UK list: their business name and address, the client's name, a numbered invoice, the date, the service and amount, any sales tax as a separate line, the total, and the due date and payment details.

Numbering

Use one sequence for all invoices, such as INV-0001, INV-0002, and so on. Do not reuse a number. If you cancel an invoice, keep its number and mark it as cancelled. The UK sequential-number rule is there so that every invoice can be traced, and a gap or duplicate makes that harder to check.

A worked example with VAT

Say you design a website for £800 and provide hosting for 12 months at £200. Both are standard-rated at 20%.

Line	Amount (£)
Website design	800.00
Hosting, 12 months	200.00
Subtotal, excluding VAT	1,000.00
VAT at 20%	200.00
Total due	1,200.00

VAT is 1,000 × 0.20 = 200, and the total is 1,200. The VAT calculator does the same sum in both directions, so you can check a price that already includes VAT.

Payment terms

Write the due date on the invoice, not only a term such as "net 30". "Due 30 days after the invoice date, by 9 December 2026" is clearer than "net 30" alone. Net 14 and net 30 are common, and the choice is yours if you agree it with the client.

In the UK, the Late Payment of Commercial Debts (Interest) Act 1998 covers payments between businesses. If no payment date is agreed, a payment is late 30 days after the customer receives the invoice, or 30 days after you deliver the goods or service, whichever is later. GOV.UK says that agreed payment periods must usually be within 60 days for business transactions, and longer periods must be fair to both businesses.

Late payment interest and compensation (UK)

Under the same Act, overdue business debts carry statutory interest of 8 percentage points above the Bank of England base rate, plus a fixed sum for recovery costs. The fixed sum is £40 for debts under £1,000, £70 for debts from £1,000 to £9,999.99, and £100 for debts of £10,000 or more. Check the current base rate and the GOV.UK pages before you rely on these figures, because the base rate changes.

As an illustration, suppose a £2,000 invoice is 60 days overdue and the total rate is 12% (a 4% base rate plus 8 points, both assumed for this example). Interest is 2,000 × 0.12 × 60 ÷ 365 = £39.45, plus the £70 fixed sum, a total of £109.45. The Act does not apply to consumers, so this is a business-to-business rule.

Follow up on a schedule

Send the invoice as a PDF, with the invoice number in the email subject. Use a clear file name, such as INV-0042 client name, so it is easy to find. Then:

1. Set a calendar reminder for a few days before the due date, using the calendar event maker, and send a short note.
2. On the due date, check the payment came in. If it did not, send a reminder that quotes the invoice number and the amount.
3. A week after the due date, send a firmer message that states the payment date and any interest you are entitled to claim.

Quick answers

Can I invoice in a currency other than pounds? Yes, but a UK VAT invoice must show the total VAT in sterling, so convert the VAT amount.

Do I need a signature on an invoice? The rules above do not require one. Check what your client's accounts team asks for.

Is a late fee in the contract enough? A contract can set its own remedy for late payment in place of the statutory interest, but a token rate may not count. Check the wording before you rely on it.