How to write an invoice as a freelancer, with a worked example

The short answer

An invoice is a request for payment that also works as a record for both sides' tax returns. It says who is billing whom, for what, how much, by when, and how to pay. The rest is detail that depends on your country and on whether you charge sales tax or VAT.

Below, I go through each part in the order you fill it in, then show a complete invoice for a made-up job, then list the mistakes that most often hold up payment.

Before you write it, agree the terms

Most slow payments start before the invoice exists. If the client never confirmed a price, a deadline for payment or who in their company receives invoices, your PDF lands in a general inbox and waits. Before the work starts, get these in writing. An email reply that says "yes, agreed" is enough for most small jobs:

• The price, either a fixed fee or a rate and an estimate of hours or days.
• What the price includes, such as the number of revision rounds.
• When you will invoice: up front, at milestones, monthly or at the end.
• The payment terms, for example 14 days from the invoice date.
• The name and email of the person who processes invoices, and whether they need a purchase order (PO) number on it.

That last point catches a lot of people. Larger companies often cannot pay an invoice without a PO number, and the accounts team will send it back rather than chase the reference themselves. Ask for it at the start, when everyone is still keen.

Step 1: your details

Put your name or business name at the top, with a postal address and an email address. If you trade under a business name as a sole trader, some countries expect your own legal name to appear as well. If you are registered for VAT, GST or sales tax, add the registration number. If you have a company number, add that too.

Keep this block identical on every invoice. Accounts teams match payees by name and bank details, and a business name that changes from one invoice to the next can trigger a new supplier check.

Step 2: the client's details

Use the client's legal company name, not the brand name you know them by, and their billing address. For business clients in the EU, include their VAT number, because some invoices depend on it (more on that in the tax step). Add the contact person or department if they gave you one, and the PO number if they use them.

Step 3: the invoice number and dates

Every invoice needs a unique number, and the numbers should run in one unbroken sequence (invoice numbering has the details). Tax offices in the UK, the EU and elsewhere expect this, and it also stops the client paying the same invoice twice or missing one. Pick a format and keep it:

• A simple counter: 001, 002, 003.
• Year plus counter: 2026-001, 2026-002. This resets each year and still sorts correctly.
• A prefix: INV-0042. Fine, as long as you never reuse a number.

If you make a mistake on an invoice you have already sent, do not edit it and resend it with the same number. Issue a credit note that cancels it, then a new invoice with the next number. That keeps your records honest and your sequence intact.

You then need two dates. The issue date is the day you send it. The due date is the day payment is expected. Write the due date as a date, such as 19 October 2026, and not only as "Net 14". A date is harder to misread. If the work happened over a different period, add a line for that too, for example "Work period: September 2026". Some countries require the date of supply when it differs from the issue date.

Step 4: the line items

This is the part people rush. Each line should let someone who was not in the project understand what they are paying for. The person approving your invoice is often a finance clerk, not the art director who hired you.

A good line has a description, a quantity, a unit (hours, days, items or a fixed fee) and a price. Compare these two:

• "Design work, 2,400.00"
• "Brand identity: logo, colour palette and type system, as quoted in Q-2026-009 (fixed fee), 2,400.00"

The second one answers the questions before they are asked. Referencing your quote number lets the client check it against what they approved, which is the fastest route to "approved, paid".

Bill extras on their own lines. If the quote included two revision rounds and the client asked for a third, show it separately with the hours. A single larger number with no breakdown invites a query, and a query restarts the payment clock.

Step 5: tax

There are three common situations, and your invoice looks different in each:

1. You are not registered for VAT, GST or sales tax. You charge no tax and do not show a tax line. In some countries you must add a sentence saying why, for example under a small business exemption.
2. You are registered and the client is in your country. You add tax at the right rate on a separate line, and show your registration number.
3. You are registered and the client is a business in another country. Often no tax is charged by you and the client accounts for it themselves under the reverse charge. The invoice usually needs a note saying so, and both VAT numbers.

The details differ a lot by country, so I wrote a separate guide on what to put on an invoice in the US, UK, EU, Canada and Australia. If you are unsure which case you are in, ask an accountant once. It is a one-off question and the answer will apply to every invoice after it.

Step 6: totals and currency

Show the subtotal before tax, the tax amount, and the total due. State the currency next to the total, even if it seems obvious. "$" means different things to clients in the US, Canada and Australia. Use the three-letter code when there is any doubt: USD, CAD, AUD, EUR, GBP.

Invoice in the currency you agreed. If you agreed a fee in euros with a client in the US, the invoice is in euros, and it is worth saying who pays the bank transfer fees. "Please pay the full amount, all bank charges at the sender's cost" is a normal line on international invoices.

Step 7: how to pay you, and the terms

Give the client everything needed to pay without writing back:

• Bank details: account name, IBAN and BIC/SWIFT for international transfers, or account and routing numbers, or sort code and account number in the UK.
• A payment link if you accept cards or a service like PayPal or Wise.
• The reference you want on the transfer. Ask for the invoice number, so you can match the payment when it arrives.
• The payment terms in one sentence: "Payment due within 14 days, by 19 October 2026."

If you charge a late fee or interest, say so here and say how much. A late fee that appears for the first time on a reminder is hard to enforce and feels like an ambush to the client. My guide on invoice payment terms covers what is normal.

A worked example

Here is a complete invoice for a made-up job. Alex is a freelance designer in the UK, registered for VAT, billing a coffee roaster for a brand identity and packaging labels. All names and numbers are invented.

INVOICE 2026-014

From:     Alex Marin Design
          12 Example Street, Bristol BS1 0AA, United Kingdom
          [email protected]
          VAT no. GB 000 0000 00

Bill to:  Harbor Coffee Roasters Ltd
          Accounts payable, 4 Quay Road, Leeds LS1 0AA
          PO number: HC-7781

Issue date:   5 October 2026
Due date:     19 October 2026 (14 days)
Work period:  September 2026
Your ref:     Quote Q-2026-009

Description                                         Qty   Unit price      Amount
Brand identity: logo, palette, type system            1     2,400.00    2,400.00
  (fixed fee, as quoted)
Packaging labels, 250 g bag, per coffee               3       350.00    1,050.00
Third revision round (two were included), hours       3        60.00      180.00

                                              Subtotal               3,630.00
                                              VAT 20%                  726.00
                                              Total due      GBP     4,356.00

Pay by bank transfer to Alex Marin Design
Sort code 00-00-00, account 00000000
Reference: 2026-014
Late payments may incur statutory interest under the Late Payment of
Commercial Debts (Interest) Act 1998.

A few things to notice. The client's PO number is there, so accounts can match it. The quote number is there, so the approver can check the price. The extra revision round has its own line with the hours. The due date is a date. The payment reference is the invoice number. Nothing on it should lead to a reply asking a question.

You can build the same thing in the free invoice generator and download it as a PDF. It runs in your browser and does not need an account.

Sending it

Send the invoice as a PDF, not as an editable document. Name the file so it makes sense in someone else's downloads folder, for example "Alex-Marin-Design-Invoice-2026-014.pdf".

Send it to the person who processes invoices, and copy your project contact. Put the invoice number, the amount and the due date in the email body, so nobody has to open the attachment to know what it is. Keep the message short:

Subject: Invoice 2026-014, Harbor Coffee brand identity, GBP 4,356.00

Hi Priya,

Attached is invoice 2026-014 for the brand identity and label work
(PO HC-7781). The total is GBP 4,356.00, due on 19 October 2026.

Bank details are on the invoice. Let me know if anything is missing.

Thanks,
Alex

Send it when the work is accepted, not two weeks later. The longer the gap, the more the work feels like old news to the client, and the further your due date moves.

Mistakes that delay payment

These are the most common ones:

• No PO number, when the client uses them. The invoice goes back to you.
• Wrong legal entity. Billing the brand name, or the parent company instead of the subsidiary that hired you.
• Vague lines like "design services". The approver has to ask the project lead what it was.
• A due date written only as "Net 30" with no date, which some teams count from the day they received it.
• Bank details missing or out of date, or a new account with no explanation, which reads like fraud to a careful accounts team.
• Editing a sent invoice and resending it under the same number. Now there are two different documents with one number.
• Sending to the wrong person and never checking it arrived.

If a due date passes anyway, a short, polite reminder sent the next working day works better than waiting a month and sending an angry one. I wrote up how to follow up on an unpaid invoice with email templates, and there is a payment reminder email generator if you want a draft to start from.

Questions