How to write an invoice as a freelancer
Your invoice is the last thing a client sees before they pay you, and small gaps on it are the most common reason money arrives late. This guide walks through every part of a freelance invoice in the order you fill it in, with the reasons behind each one.
Invoicing · Published 2026-10-07
1. Start with clear business details
Put your name or business name, email address and, if you have one, a business address at the top. Clients often forward invoices to an accounts team that has never spoken to you, so the invoice needs to make sense on its own.
If you are registered for VAT, GST or sales tax, your tax registration number must appear here. In the UAE, for example, a tax invoice must show the supplier's Tax Registration Number (TRN) and the words Tax Invoice. In the UK and EU, a VAT invoice must show your VAT number. If you are not registered, leave tax details off rather than inventing a number.
2. Add the client's details exactly as they appear in the contract
Use the client's legal company name, not the name of the person you worked with. Large companies match invoices against supplier records and purchase orders, and a name mismatch can send your invoice to a queue of exceptions.
If the client gave you a purchase order (PO) number, put it on the invoice. Many finance teams will not pay an invoice without a PO reference, and they will not always tell you that is the problem.
3. Give the invoice a unique number and a date
Every invoice needs a number that you never reuse. The simplest system is sequential: INV-0001, INV-0002 and so on. Some freelancers prefix the year (2026-001) or a client code (ACME-004). Any system works as long as each number is unique and you can find the invoice again later.
Add the invoice date (the day you issue it) and, separately, the due date. Tax authorities in most countries expect invoice numbers to be sequential with no gaps, so if you cancel an invoice, keep a record of it rather than deleting the number.
4. Describe the work so nobody has to ask
Each line item should say what you delivered, not just the category of work. Website design is vague; Homepage and 4 inner page designs, 2 revision rounds is clear. A specific description answers the question the approver will ask before they sign off.
For each line, include the quantity (hours, days, items or 1 for a fixed fee), the rate and the line total. If you agreed a fixed price, a single line with quantity 1 is fine.
- Hourly work: list the hours and the hourly rate, and keep a timesheet ready in case the client asks.
- Fixed-price projects: list the milestone or deliverable and the agreed amount.
- Expenses you are passing on: list them on separate lines so they are not confused with your fee.
5. Show subtotal, tax and total
Add the line totals to get the subtotal, apply any tax rate you are required to charge, and show the final amount due. Always state the currency, especially with international clients. 1,000 means very different things in dollars, dirhams and rupees.
If you are not sure whether you must charge tax, check with a local accountant. The rules depend on your country, your income and sometimes where your client is based.
6. Set payment terms and explain how to pay
Payment terms tell the client when the money is due. Common choices are Due on receipt, Net 14 or Net 30 (payment within 14 or 30 days of the invoice date). Write the actual due date as well, because nobody wants to count days.
Then make paying easy. List the exact payment methods you accept: bank account details (account name, IBAN or account number, SWIFT or routing code), a payment link, or a platform such as PayPal or Wise. Every extra step you remove is a day sooner you get paid.
7. Add a short note
The notes area is a good place for a thank-you, a reminder of the project name or a line such as Please include the invoice number as the payment reference. Keep it short. Long legal text belongs in your contract, not on the invoice.
Common mistakes that delay payment
- Sending the invoice to your contact instead of the accounts payable email address.
- Missing PO number or wrong company name.
- No due date, so the invoice sits in a pile with no urgency.
- Payment details that are incomplete, for example an IBAN without the account holder name.
- Sending an editable Word file instead of a PDF, which looks unprofessional and can be changed.
Before sending, read the invoice once as if you were the client's finance team. If anything would make you ask a question, fix it now.
Making it with Zonlet
Zonlet's invoice generator has a field for each part above: your details and logo, client name, line items, tax rate, currency, due date and notes. The preview updates as you type, and you can download a PDF without creating an account. If you sign in, you can save invoices and share a link your client can open in the browser, and Pro adds automatic invoice numbering.