How to write an invoice

To write an invoice you need seven things on the page: your business details, the client's billing details, a unique invoice number, the issue date and a due date, an itemized list of what you are charging for with quantities and rates, the total amount due (with any tax shown as its own line), and the payment terms plus how to pay. Those elements turn a request for money into a document your client's finance team can approve and pay, and that both sides can use as a tax record. The rest of the work is getting each field specific: the exact legal entity you are billing, a real calendar due date instead of a vague term, and clear line items that show where every dollar comes from. You can build one field by field in the free invoice generator, or start a new invoice and fill it in as you read.

The legal baseline: US, UK, and EU

What an invoice is legally required to carry depends on where you are and whether you charge tax. The gap between the US and Europe is wide, so treat these as three separate rulebooks.

United States: substantiation, not a prescribed template

There is no single federally mandated invoice format in the US. The IRS states that, with few exceptions, the law does not require any special kind of records, and you may use any system that clearly shows your income and expenses. What the IRS does require is substantiation: a supporting document should identify the payee, the amount paid, proof of payment, the date incurred, and a description of the item. The same IRS guidance lists invoices among the documents that show a business's gross receipts, so an invoice is the income-side record the IRS expects you to keep.

Where US rules do get specific is sales tax, and that is set state by state. In New York, for example, you must separately state the amount of sales tax due on the invoice or receipt you give the customer, and itemize each item sold with enough detail to determine whether it is taxable. Texas follows the same pattern: the Comptroller requires you to separately state the sales tax you charge unless you give written notice that tax is included in the price. The lesson across states is the same: if the sale is taxable, show the tax as its own line, never buried in the item price.

A business tax ID on a US invoice is usually the EIN, which the IRS describes as a federal tax ID number for businesses, tax-exempt organizations, and other entities. No US law requires the tax ID to appear on the invoice itself, unlike the VAT-number rules in Europe. For retention, the IRS baseline is to keep records for 3 years, rising to 6 years if you understate income by more than 25%, so keep every invoice you send or receive for at least that long.

United Kingdom: VAT invoices carry more

A non-VAT-registered UK business issues a plain commercial invoice with no VAT charged and no VAT number. GOV.UK lists what it must include: a unique identification number, your business name and address, the customer's details, a description of the charge, the supply date, the invoice date, and the total. You only issue a full VAT invoice when both you and your customer are VAT registered.

A full UK VAT invoice adds several particulars. HMRC's guidance requires a sequential number that uniquely identifies the document, your VAT registration number, both the time of supply (the tax point) and the date of issue, and, per line, the VAT rate and the amount payable excluding VAT, plus the total VAT chargeable expressed in sterling. The tax point and the issue date are two separate fields that can differ, which is a common source of error.

European Union: the Article 226 list

Across the EU, the required contents of a full VAT invoice are harmonized by Article 226 of the VAT Directive. As the European Commission reproduces the list, a full invoice must show the date of issue, a unique sequential number, the supplier's VAT identification number, the full name and address of both parties, a description and quantity of the goods or services, the unit price excluding VAT, the VAT rate and amount payable, and a breakdown of VAT by rate. The customer's VAT number is required where the customer is liable for the tax, as in reverse-charge and intra-EU sales. For low-value supplies the Directive allows a simplified invoice with a reduced field set. The unique sequential number rule is not optional: the Directive text calls for a sequential number that uniquely identifies the invoice, which is why a consistent numbering scheme matters. If you are billing across borders, the guide to cross-border invoices goes deeper on currency, VAT, and wire details.

Sources verified 2026-08-19 by the JupiterInvoice team.

How to write an invoice, step by step

Work top to bottom. Each step maps to a block on the finished page, and none of them takes long once you have your business details saved.

1. Add your business details and a unique invoice number. Put your business name, address, and contact details at the top, then assign a unique sequential invoice number that no other invoice shares. A consistent format matters for tax and for finding invoices later; the invoice numbering scheme guide covers the options.
2. Add the client's billing details. Name the exact legal entity you are billing, with its billing address and the accounts payable or finance contact if you have one. Billing the wrong entity is a top reason invoices get returned.
3. Set the issue date and a concrete due date. Write the invoice date, and state the due date as a real calendar date, not just a term like Net 30, so there is nothing to interpret. The due date calculator turns a term into a date for you.
4. Itemize the work with descriptions, quantities, and rates. List each product or service on its own line with a clear description, the quantity or hours, and the unit price, so every charge is traceable. Vague single-line invoices ("Consulting, $6,000") invite questions and delay.
5. Total it up, with tax shown separately. Add a subtotal, show any sales tax or VAT as its own line rather than folding it into the prices, then show the total amount due. This is a legal requirement wherever the sale is taxable, and it makes your invoice easy to reconcile.
6. State payment terms and how to pay. Spell out the payment terms, any late fee, and exactly how to pay: bank details, or a payment link, so the client can act without emailing you back. See Net 30 and other terms to pick the right one.
7. Review, then send the link. Check the numbers and the billing entity, then send the invoice as a private link so the client can view it, add a PO number, and approve it. A link means the recipient can fix their own PO or billing address without a reissue.

A worked example

Here is a complete invoice for a freelance designer billing a business client, with every field from the steps above filled in.

In this example the tax line is computed on the $300 of printed guidelines and stated separately, while the design work is left untaxed. Which services are taxable varies by state, so check your state's rules before you decide what to tax. The point to copy is the mechanics: when an invoice mixes taxable and nontaxable lines, compute the tax only on the taxable ones and show it on its own line.

Common mistakes that delay payment

Late payment is the default, not the exception: BILL reports that about half of all small-business invoices are paid at least two weeks late. Most of that is friction you can design out of the invoice itself.

• No explicit due date. "Net 30" alone forces the client to do date math. Write the actual date. FreshBooks, analyzing more than a million invoices, found that invoices with stated payment terms were paid more than 88% of the time, regardless of the specific term.
• Terms longer than they need to be. In the same FreshBooks data, 7-day terms were paid within a week 58% of the time versus 40% for 30-day terms. Shorter stated terms pull cash forward and shrink the tail of very-late payers.
• A vague, single-line charge. "Services rendered, $6,000" gives the AP team nothing to check. Itemize so each charge is self-explanatory.
• Billing the wrong entity. Invoicing the brand name instead of the legal entity, or the wrong subsidiary, sends the invoice into a loop of corrections. Confirm the exact entity before you send.
• No easy way to pay. Stripe reports Xero customers get paid 14 days faster when they accept online payments on the invoice. A pay-now link beats a buried bank number.
• Reusing invoice numbers or leaving gaps. Duplicated numbers break your records and, in VAT countries, break the law. Pick a scheme and keep it sequential.

If an invoice does slip past due, work out the enforceable charge with the late fee calculator before you add a fee. And if you are unsure whether you should be sending an invoice or a receipt at all, the guide on how an invoice differs from a receipt settles it.

Sources verified 2026-08-19 by the JupiterInvoice team.