What extra details does a VAT invoice need?

HMRC VAT Notice 700/21 adds a sequential invoice number, the time of supply, your VAT registration number, the quantity and unit price of each item, the VAT rate and the amount excluding VAT for each line, the total excluding VAT, any cash discount, and the total VAT in sterling.

Is there a required invoice format in the US?

There's no federal invoice format. In practice an invoice should show your business details, the customer, a unique number, the date, what you sold, the amounts, any sales tax your state requires you to charge, the total and when it's due. The IRS says to keep business records for at least 3 years in most cases.

Should a discount be taken off before or after tax?

Before. For VAT, HMRC charges tax on the price actually paid, so a 10% discount on £1,000 of work at 20% VAT is £900 plus £180 VAT, £1,080 in total.

How long do I have to keep invoices?

In the UK, VAT records generally have to be kept for at least 6 years. In the US the IRS says 3 years in most cases, longer in some situations, such as 6 years if income was substantially under-reported.

How to Write an Invoice (US & UK): What It Must Include

Q: What must be on an invoice in the UK?

GOV.UK lists a unique invoice number, your name or business name, address and contact details, the customer's name and address, a clear description of what you're charging for, the supply date, the invoice date, the amounts charged, any VAT, and the total owed. Limited companies must use their full registered name.

An invoice is more than a request for money: it's a record your customer and your tax authority rely on. Get the details right and you're paid faster, with fewer questions. Here's what an invoice needs in the UK and the US, the extra rules for VAT invoices, and how to set out tax, discounts and payment terms.

To make one now, use the free invoice generator: it works out the totals and flags anything missing for your country.

What every invoice should show

A unique invoice number, ideally in sequence (INV-0041, INV-0042…).
Your details: your name or business name, address and contact details, and your tax number if you're registered.
Your customer's details: their name or company, and address.
The dates: the invoice date, and the date the work was done or goods supplied if it's different.
What you're charging for: a clear description of each item, with the quantity and price.
The money: the amounts, any tax, and the total owed.
When and how to pay: the due date or payment terms, and your bank details or a payment link.

UK invoices

GOV.UK says an invoice must include a unique identification number, your company name, address and contact information, the name and address of the customer, a clear description of what you're charging for, the supply date, the date of the invoice, the amounts charged, any VAT, and the total amount owed.

Sole traders must also show their own name and any business name, plus an address where legal documents can be delivered if they trade under a business name.
Limited companies must use their full company name as it appears on the certificate of incorporation. If you list any directors' names, you must list them all.

VAT invoices

If you're VAT-registered and selling to another VAT-registered business, you must issue a VAT invoice. HMRC's VAT Notice 700/21 says it must show:

a sequential number that uniquely identifies it;
the time of supply (tax point) and the date of issue, if different;
your name, address and VAT registration number;
the customer's name and address;
a description of each item, its quantity, unit price, VAT rate and amount excluding VAT;
the total excluding VAT, the rate of any cash discount, and the total VAT in sterling.

For supplies of £250 or less including VAT you can issue a simplified invoice showing your name, address and VAT number, the time of supply, a description, and the total including VAT for each rate.

US invoices

There's no federal law on invoice format in the US, but businesses and their accountants expect the same basics: your business name and contact details, the customer, a unique invoice number, the date, what you sold, the amounts, any sales tax, the total and the due date. Sales tax depends on your state and what you sell: many services aren't taxed, while most goods are. The sales tax calculator shows each state's rate. Many US businesses call a quote an estimate.

Keep copies: the IRS says to keep records that support your income for at least 3 years in most cases, and longer in some situations.

Australia and India: "tax invoices"

In Australia, a GST-registered business must give a tax invoice within 28 days if asked, unless the sale is $82.50 or less including GST. The ATO says it must show that it's a tax invoice, your identity and ABN, the date, a description, quantity and price of what's sold, the GST, and how much of each sale is taxable; from $1,000 it must also show the buyer's identity or ABN. In India, a GST tax invoice shows your GSTIN and the GST charged.

A worked example

A UK web designer invoices a bakery for a £2,400 website and 3 months of hosting at £45 a month, all with 20% VAT:

Item	Qty	Price	VAT	Amount
Website redesign	1	£2,400.00	20%	£2,400.00
Hosting and maintenance (monthly)	3	£45.00	20%	£135.00
Subtotal				£2,535.00
VAT at 20%				£507.00
Total				£3,042.00

Discounts come off before tax. If the designer gave 10% off £1,000 of work instead, the invoice would show £1,000, a £100 discount, £900 net, £180 VAT and £1,080 total. Deposits are shown as an amount paid, with the balance due underneath.

Numbering, terms and getting paid

Number in sequence. HMRC requires it for VAT invoices, and it makes gaps and duplicates easy to spot. Keep a prefix if you like, such as INV-0042, then INV-0043.
State your payment terms, such as "due within 14 days". In the UK, if no date is agreed, a business customer's payment is late 30 days after it gets the invoice or the goods or service, whichever is later.
Late payment in the UK: between businesses you can claim statutory interest of 8% plus the Bank of England base rate, and a fixed sum for recovery costs: £40 for debts under £1,000, £70 up to £9,999.99, and £100 for £10,000 or more.
Make it easy to pay: put your bank details and, if you use one, a payment link on the invoice.

The invoice generator numbers your invoices, works out tax by rate with discounts applied first, shows deposits and the balance due, and saves your business details in your browser for the next one. For the tax on its own, see the VAT calculator or GST calculator.

Sources: GOV.UK "Invoicing and taking payment from customers" and "Late commercial payments"; HMRC VAT Notice 700/21; ATO "Tax invoices"; IRS "How long should I keep records?". General guidance, not legal or tax advice. Last reviewed October 2026.