The required core
These appear on every valid invoice regardless of where you are.
- The word “Invoice”. It sounds trivial, but a document that does not identify itself can be treated as a statement or a quote, neither of which creates a payable debt.
- A unique sequential number. See invoice numbering.
- The issue date, and separately the due date.
- Your legal name and address. If you are a sole trader this is your own name unless you have registered a trading name. A mismatch between the name on the invoice and the name on the bank account is one of the most common reasons payment stalls.
- Your client’s name and address, ideally addressed to a person or department rather than the company in general.
- A description of what was supplied, itemised, with quantity and rate.
- The total due, with the currency stated explicitly.
If you are VAT registered in the UK
Add your VAT registration number, the rate applied to each item or to the invoice as a whole, and the VAT amount shown as its own line rather than folded into the total. Your customer cannot reclaim input VAT without these, so their accounts team will return the invoice — which is a fortnight of delay for a field you could have filled in.
If you invoice a VAT-registered business in another EU country, their VAT number belongs on the invoice too, along with a note on the reverse charge where it applies.
If you are in the US
There is no federal invoice format. Where sales tax applies it is shown separately from the subtotal, and the applicable rate depends on the state and often the locality. If you are invoicing across state lines, whether you charge tax at all depends on nexus rules that differ by state — worth checking once for your situation rather than guessing per invoice.
For contractors, clients will usually want your EIN or SSN on file via a W-9 rather than on the invoice itself. Do not put a Social Security number on a document that will be emailed around.
The fields that are not required but get you paid
- Payment details in full. Sort code and account number, or routing and account number. An invoice that requires someone to go looking for your bank details gets set aside.
- A reference the client asked for. Many companies will not pay an invoice without a purchase order number on it. Ask before invoicing.
- A named contact. Invoices addressed to nobody circulate until someone claims them.
What to leave off
Do not include a Social Security number, a full bank password or card details, or anything you would not want in an email attachment that gets forwarded three times. An invoice is not a confidential document in practice, however you send it.
Last reviewed August 2026.