How to write an invoice (with a free template)
Exactly what to put on an invoice so it looks professional and gets paid — the required fields, a clear example, payment terms, and the common mistakes that delay payment.
An invoice is a simple document with an important job: tell a client exactly what they owe, why, and how to pay it. Get the details right and it gets paid without a chase. This guide covers every field an invoice needs, a clear example, and the small choices that get you paid faster.
What every invoice must include
Whether you write it by hand or generate it, a complete invoice has the same building blocks. Missing fields are the most common reason an invoice gets questioned instead of paid.
| Field | What it is |
|---|---|
| Your business + logo | Who the invoice is from |
| Bill to | Client name, company and email |
| Invoice number | A unique reference (e.g. INV-0007) |
| Issue + due date | When sent and when payment is due |
| Line items | Description, quantity, rate, amount |
| Subtotal, tax, total | The math, with the total unmissable |
| Payment details | How to pay — ideally a "Pay now" link |
| Notes / terms | Thank-you, late-fee or payment terms |
A simple example
Say you are a designer billing Acme Co. for two services. Your invoice lists "Brand strategy — 1 × $1,200" and "UI/UX design — 1 × $1,800", a subtotal of $3,000, 8.5% tax of $255, and a bold total of $3,255 due in 14 days — with a button to pay by card. That is it. Clear, scannable, payable.
Choosing payment terms
Terms set expectations. Spell them out on the invoice rather than relying on "due on receipt", which clients interpret loosely.
- Net-7 to net-14 is standard for freelancers and small jobs
- Charge a 30–50% deposit on larger projects
- State any late fee up front so it is not a surprise
- Offer online card payment to remove the biggest delay
Numbering and records
Use sequential invoice numbers (INV-0001, INV-0002…) so both you and your client can reference them, and keep a copy of every invoice and its paid status. A tool that tracks sent / viewed / paid status saves you from guessing whether a client saw it.
Mistakes that delay payment
Most late payments trace back to friction or ambiguity, not unwillingness.
- No clear due date or total
- Vague line items the client cannot map to the work
- Bank-transfer-only (adds days vs a card payment)
- No follow-up — automatic reminders fix this
Write it in a minute with CoreInvoice
CoreInvoice fills in the structure for you: your logo and branding, sequential numbering, line items with tax and discount, online card payments that land in your own account, and sent / viewed / paid tracking — so the invoice is professional and payable without starting from a blank page.
FAQ
What information is legally required on an invoice?+
Requirements vary by country, but a complete invoice always includes your business details, the client, a unique invoice number, issue and due dates, an itemized list, the total (with any tax), and payment instructions.
How do I number invoices?+
Use a simple sequential scheme like INV-0001, INV-0002. Consistent numbering makes invoices easy to reference and reconcile.
How can I get paid faster?+
Add a clear due date, offer online card payment, bill a deposit on larger jobs, and turn on automatic reminders.
Create a professional invoice
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