How to Invoice as a Freelancer: Everything You Need to Know

Nobody teaches you this. You finish a piece of work, a client says "great, send me the invoice," and suddenly you are staring at a blank document trying to remember what goes on one of these things. You roughly know what an invoice looks like because you have received them from companies, but creating your first one as the person requesting payment feels different.

This is the practical guide for that moment.

What an invoice actually needs to include

An invoice is a formal request for payment. For it to work, it needs to be complete enough that someone else's finance team can process it without asking you any questions.

Your details go at the top: your full name or business name, your address, your email, and your phone number. If you are VAT registered, your VAT number goes here too. If you are not VAT registered, you do not need to include one.

Then the client's details: the company name, the name of the person or department you are billing, and their billing address. If they gave you a purchase order number or an internal reference code, include it here. Large companies will often not process an invoice that is missing their PO reference.

The invoice number comes next. This should be a unique identifier in a sequential series. INV-001, INV-002, or a year-based format like 2026-001 are both fine. The rule is that every invoice has a different number and you never skip or reuse one. Gaps in the sequence look like errors.

Two dates: the issue date (today) and the due date (when you want to be paid). If you send the invoice on 1 June and your terms are Net 30, the due date is 1 July.

The line items are the heart of the invoice. Each thing you are charging for gets its own row. Include a description, a quantity, a unit price, and a line total. "Copywriting, 3,000 words at £0.12 per word, £360" is a line item. "Writing work" is not. The description should be specific enough that the person reading it knows exactly what they received.

Below the line items: a subtotal, any applicable tax, and the total. If you work across different countries or currencies, make the currency explicit.

Payment details at the bottom: your bank account name, sort code, and account number (UK), or IBAN and BIC for international transfers, or your PayPal address, or however you accept payment. If the person reading your invoice cannot figure out how to send you money without asking, you have introduced a delay.

When to send it

The day you finish the work, or the day you hit the agreed milestone. Not at the end of the week. Not when you get around to it. The day the work is done.

There are two reasons for this. The first is practical: Net 30 starts from the invoice date, so every day you wait is a day added to when you get paid. Send it a week late and you have effectively turned Net 30 into Net 37 for no reason.

The second reason is psychological. Clients feel the value of your work most strongly on the day they receive it. An invoice that arrives the same day as the deliverable feels like a natural conclusion to the project. An invoice that arrives a fortnight later feels like admin.

How to number your invoices

Pick a format and stick to it. A year-prefixed format (2026-001, 2026-002) makes it easy to find invoices from a specific period. A simple sequential format (INV-001, INV-002) works just as well. What matters is consistency and uniqueness.

Never reuse a number, even if an invoice was sent in error and cancelled. Issue a credit note for any amount you need to reduce or remove, then continue the sequence from where you left off.

If you ever need to correct an invoice after sending it, do not edit and resend the original. Issue a credit note for the incorrect amount and a new invoice with the right amount. Both documents get unique numbers and both stay in your records. This keeps your books clean and prevents any questions from your accountant or tax authority.

What payment terms to set

Net 30 is the default in professional services and is appropriate for most corporate clients. Net 14 or Net 15 is reasonable for smaller clients and one-off jobs where there is no complex approval process. Net 7 works for very short-term work with individuals.

For larger projects, ask for a deposit upfront. A 25% to 50% deposit before work begins is standard practice in many creative and consulting fields. It reduces your risk and filters out clients who are not serious about the project.

Put the due date explicitly on the invoice as a calendar date, not just the term. "Due 1 July 2026 (Net 30)" is unambiguous. The client can put it in their calendar and you can reference the exact date if it goes past due.

What to do when it is not paid

Wait until the due date passes before doing anything. Then send a short, factual reminder: the invoice number, the amount, the due date, and a request to confirm when payment is coming. Do not apologize for asking. Do not over-explain.

If that gets no response after five business days, send a firmer follow-up and, if possible, call rather than email. Most late payments are resolved by a phone call.

Keep a record of every invoice: the number, the client, the amount, the due date, and when it was paid. A simple spreadsheet is enough. That record is what you need if you ever have to escalate a late payment formally.

The tool for doing this

You do not need accounting software to invoice professionally as a freelancer. The invoice tool creates a clean, numbered PDF invoice in minutes. Fill in your details once and they save for future invoices. No signup, no subscription, no data stored on a server. Download the PDF and send it.

Professional invoicing is mostly about consistency. The same format, the same numbering, sent on the same day every time. That habit takes about ten minutes to establish and saves hours of confusion later.

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Related articles

• Invoice Payment Terms: What They Mean and Which Ones to Use
• What to Do When a Client Does Not Pay Your Invoice