Invoice Generator

What an invoice must contain

The rules depend on where you and your customer are, but the core is the same nearly everywhere, and the tool has a field for each part. The UK government’s guidance for businesses lists what every invoice must include (https://www.gov.uk/invoicing-and-taking-payment-from-customers/invoices-what-they-must-include):

• a unique identification number
• your company name, address and contact information
• the company name and address of the customer you are invoicing
• a clear description of what you are charging for
• the date the goods or service were provided (the supply date)
• the date of the invoice
• the amounts being charged, the VAT amount if applicable, and the total amount owed

The same page adds two points that are easy to miss. A sole trader’s invoice must show the owner’s own name as well as any business name. A limited company’s invoice must show the full company name as it appears on the certificate of incorporation.

There is no separate supply-date field in the editor. If the supply date differs from the invoice date, add it as a custom field under Invoice details (for example “Supply date”) and it prints with the other dates.

If you are registered for VAT or GST, a tax invoice usually needs more: your registration number, the rate and amount of tax, and the net amount. The European Commission’s summary of the EU rules lists a date of issue, a unique sequential number, the supplier’s and customer’s details and VAT numbers, a description with quantities and unit prices, and the VAT rates and amounts (https://taxation-customs.ec.europa.eu/taxation/vat/vat-businesses/invoicing_en). Use the tax ID fields for both parties, name each tax in the Taxes section, and choose the “Tax Invoice” title if your jurisdiction uses that wording.

In the United States there is no federal invoice format, and sales tax is set by states and localities rather than nationally. What the IRS asks for is records: it names invoices among the supporting documents for both gross receipts and expenses (https://www.irs.gov/businesses/small-businesses-self-employed/what-kind-of-records-should-i-keep). Check your own state’s revenue department for what a taxable sale must show.

How invoice numbering works

An invoice number has one job: to identify that document and no other. For VAT invoices HMRC words the requirement as “a sequential number based on one or more series which uniquely identifies the document” (https://www.gov.uk/hmrc-internal-manuals/vat-trader-records/vatrec5010). A number can mix letters and digits, and you can run more than one series, for instance one per client or per year.

The tool reads the numbers of the invoices saved in this browser and suggests the next one in the series: after INV-0006 it offers INV-0007. Type over it with your own scheme once, say 2026-041, and the prefix and the zero-padding are remembered, so the next suggestion is 2026-042. If you reuse a number that is already in your history, a warning appears beside the field. It is a warning, not a block, because only you know whether you are correcting an old invoice.

The suggestion only knows about invoices saved in this browser. If you also issue invoices elsewhere, check the number before you send.

Payment terms explained

Payment terms tell the client when the money is due. Choosing a preset sets the due date from the issue date; editing the due date by hand switches the terms to Custom.

• Due on receipt: payable as soon as the client receives the invoice. Common for small jobs and new clients.
• Net 7, Net 15, Net 30, Net 60: payable within that many calendar days of the invoice date. Net 30 is the usual default between businesses.
• Custom: any due date you choose, for example the last day of the month.

Terms are part of your agreement with the client, so they belong in your contract or quote as well as on the invoice. Where nothing was agreed, the law may fill the gap. In the UK a business-to-business payment is late 30 days after the customer gets the invoice, or after delivery if that is later (https://www.gov.uk/late-commercial-payments-interest-debt-recovery), and statutory interest on late commercial payments is 8% plus the Bank of England base rate (https://www.gov.uk/late-commercial-payments-interest-debt-recovery/charging-interest-commercial-debt). Other countries set their own rules.

State how you want to be paid in the Payment instructions box. It prints on the invoice and is remembered for the next one. If slow payment is a recurring problem, the invoice factoring cost calculator shows what it costs to be paid early by a factor.

Sales tax, VAT and GST on an invoice

The tool does the arithmetic for any rate you give it. It does not decide whether a sale is taxable, which rate applies, or whether you must register. Those depend on your jurisdiction and on what you sell.

Add one tax line per tax, each with its own name and rate. A Canadian invoice might carry GST 5% and PST 7%; an Indian one CGST 9% and SGST 9%. Each tax is calculated on the same taxable amount and shown on its own row. Taxes that compound, where one tax is charged on top of another, are not supported.

Use the Taxable tick box on each line for mixed invoices, where labour, freight or exempt goods should not be taxed. When some lines are taxed and others are not, the untaxed lines are marked “Not taxed” on the invoice.

Choose “Included in prices” if your prices already contain the tax, as consumer prices do in VAT and GST countries. The total stays what you typed, and the invoice shows how much of it is tax. Choose “Added to prices” if tax goes on top, as with US sales tax and most business-to-business VAT invoices.

To check a single figure, use the sales tax calculator, the GST calculator or the VAT calculator. The GST and sales tax compliance guide covers registration, place of supply and record keeping.

How the totals are calculated

Every amount is held as a whole number of the currency’s smallest unit (cents for dollars, whole yen, thousandths of a Kuwaiti dinar), so the rounding errors of ordinary computer arithmetic cannot occur: 0.1 + 0.2 is exactly 0.30. Rounding is always half away from zero, so 1.005 becomes 1.01. The steps run in this order:

1. Line amount = quantity × unit price, rounded to the currency’s smallest unit. A line discount (a percentage of that amount, or a fixed sum) is then subtracted.
2. Subtotal = the sum of the rounded line amounts.
3. Invoice discount = a percentage of the subtotal, rounded, or a fixed amount. It cannot exceed the subtotal. It is shared between taxable and non-taxable lines in proportion to their amounts.
4. Taxable amount = the taxable lines, less their share of the invoice discount, plus shipping if you marked shipping as taxable.
5. Each tax = taxable amount × its rate, rounded on its own. In “Included in prices” mode the tax is taken out instead: net = taxable amount ÷ (1 + the sum of the rates), the difference is the tax, and it is split between the taxes in proportion to their rates so the parts always add up.
6. Total = subtotal − invoice discount + taxes (when added to prices) + shipping or fee.
7. Balance due = total − amount already paid. If more was paid than the total, the invoice shows a credit balance instead. Marking the invoice Paid sets the balance to zero.

This order, line rounding first, is the common convention, but some accounting systems round tax per line or only at the end, which can move a total by a cent. If your accountant’s software disagrees by a cent, that is the reason, and their method should win for your books. The guide to building an Excel invoice template with mixed taxable lines walks through the same rounding decision in a spreadsheet.

Where your data is stored

Everything you type stays in this browser. The draft, your business profile, saved clients, invoice history, logo and signature are written to the browser’s local storage on your device. The page makes no network request with your invoice data, the PDF is built on your device, and no field value is sent to analytics.

That has consequences worth knowing. Clearing your browser’s site data, or using a private window, removes the stored invoices. A different browser or device starts empty. Browsers limit local storage to a few megabytes per site, which is room for hundreds of invoices because your logo is stored once and shared between them.

Use History → Backup → Export all data to download one JSON file with everything in it. Keep it as your backup, and import it on another device to carry on there. Importing adds to what is already in the browser rather than replacing it. “Delete all my data” in the same place removes everything at once.

Tax authorities expect you to keep copies of the invoices you issue, often for years. HMRC, for example, says VAT-registered businesses must keep a copy of every VAT invoice issued and generally keep VAT records for at least 6 years (https://www.gov.uk/guidance/record-keeping-for-vat-notice-70021). Browser storage is a convenience, not an archive: keep the PDFs you send.