How to write an invoice
Give your client a clear record of the work, the amount due and how to pay.
Free toolInvoice GeneratorCreate a clear invoice with a live preview, calculated totals and a PDF made in your browser.Create an invoiceStart with the details both sides need
An invoice identifies the seller and customer, describes the charge and states what is due. Add a unique reference and the dates your client needs to process it.
| Include | What to check |
|---|---|
| Seller and customer | Names, addresses and relevant contact or tax details. |
| Invoice reference and dates | A unique number, issue date and payment due date or terms. |
| Description and price | What was supplied, the quantity or hours, the rate and each line amount. |
| Adjustments and balance | Discounts, tax, shipping, any payment already received and the remaining amount due. |
| Payment instructions | The agreed method and enough detail for the client to pay securely. |
Requirements vary. For example, UK government guidance lists additional requirements for VAT invoices. Check the rules that apply to your transaction.
Make the work easy to recognise
Use descriptions that let the client connect each line to the agreement. Replace “services” with the project, period or deliverable when that context helps.
For hourly work, show hours and the agreed hourly rate. For a fixed fee, use a quantity of one. Add a purchase order reference if the client requires it.
Work through a discount, tax and deposit
Here is a fictional invoice calculated and checked in floi on 27 October 2026. It uses one tax rate after the discount. Shipping is zero.
| Step | Calculation | Amount |
|---|---|---|
| Brand identity | 1 × USD 1,200 | USD 1,200.00 |
| Website design | 12.5 × USD 80 | USD 1,000.00 |
| Subtotal | 1,200 + 1,000 | USD 2,200.00 |
| Discount | 10% of 2,200 | − USD 220.00 |
| Tax | 20% of 1,980 | USD 396.00 |
| Total | 1,980 + 396 | USD 2,376.00 |
| Balance due | 2,376 − 500 already paid | USD 1,876.00 |
To repeat it, enter those two items, a 10% discount, 20% tax and 500 in Amount paid. The percentages are an example, not a recommended rate. Tax order, rounding and treatment of shipping can differ by jurisdiction.
Choose how to make and send it
Use a method that fits the number of invoices you issue and the records you need to keep.
Browser generator
Fill in a form and save a PDF. Floi calculates the amounts on your device. You send and track the invoice yourself.
Document or spreadsheet
Use an editable template if you need custom fields. Check formulas and page breaks before exporting a PDF.
Invoicing software
A dedicated service may offer recurring invoices, payment links, reminders and accounting records. Check its pricing and data handling.
Check the file before it leaves
- Confirm the client, reference, dates and descriptions.
- Recalculate the totals and check the currency, tax rate and amount already paid.
- Open the exported file. Check every page and confirm payment instructions are correct.
- Send it through the agreed channel and keep a copy with your records.
A PDF can preserve the layout, but it does not verify the information inside. Your own record should let you identify the invoice and any later correction.