Sending your first invoice as a freelancer can feel surprisingly intimidating. You’ve done the work — now you need to get paid. Here’s everything you need to know to send a professional invoice that gets results.
What every invoice must include
A proper invoice is a legal document, and most countries have minimum requirements for what it must contain. At a minimum, include:
- Your name and address — or your business name if you operate under one
- Your client’s name and address — the legal entity you’re billing
- A unique invoice number — used for your records and theirs
- Invoice date and due date (or payment terms like “Net 30”)
- A clear description of work — what you did, when, and for what project
- The amount charged — per item or as a total, with any applicable taxes shown separately
- Your payment details — bank account, PayPal, or however you accept payment
If you’re VAT-registered, you’ll also need your VAT number and to show the tax amount separately. See our VAT guide for the full breakdown.
How to number your invoices
Invoice numbers need to be unique and sequential — but the format is up to you. Common conventions:
- Simple sequence: 001, 002, 003 …
- Year-prefixed: 2026-001, 2026-002 … (resets each year)
- Client-prefixed: ACME-001, ACME-002 … (useful if you have many clients)
Never reuse or skip an invoice number. Gaps look suspicious to accountants and tax authorities. If you void an invoice, note it as voided rather than deleting it.
Choosing the right payment terms
Payment terms tell your client when you expect to be paid. Common options:
- Due on receipt — payment expected immediately
- Net 15 — payment due within 15 days
- Net 30 — payment due within 30 days (the most common for B2B)
For new clients or larger projects, consider asking for a deposit (25–50%) upfront before you start work. This protects you and signals to the client that you’re serious.
When to send the invoice
Send your invoice as soon as the work is complete — or, for ongoing retainers, on the same day each month. Delaying your invoice often delays your payment. Clients work through accounts payable queues; the earlier you enter that queue, the earlier you get paid.
Following up if payment is late
Even with clear terms, some invoices go unpaid past the due date. Don’t assume the client forgot intentionally — emails get buried. A short, polite follow-up 1–2 days after the due date is entirely appropriate and expected. See our guide on following up on unpaid invoices for a proven sequence of messages.
Making it easy for yourself
A good invoicing app handles the numbering, formatting, and follow-up reminders for you. Billino generates professional, compliant invoices in seconds — including PDF output ready to send directly to clients. The less time you spend on admin, the more time you have to do work that pays.