How to Write a Professional Invoice (with Free Template)

A professional invoice does one job: leave nothing for the client to interpret. Every missing detail (your tax ID, the PO number, the payment method) is a reason for accounts payable to push the bill to the next week.

Below is what a professional invoice actually contains, field by field. Skip to the bottom for a copy-paste template you can use today.

The 11 fields a professional invoice must include

1. The word "Invoice" — at the top, clearly. Not "Statement," not "Bill." AP systems often scan for this exact word.
2. A unique invoice number — sequential (INV-001, INV-002...) or date-based (2026-05-001). Never reuse a number.
3. Your business name and contact info — name, address, email, phone, website.
4. Your tax ID — EIN in the US, VAT number in the EU/UK, ABN in Australia. Many enterprise AP systems will not pay without it.
5. The client's name and address — exact legal entity. If they have a separate AP email, use it.
6. A PO or reference number if they gave you one. This is the #1 reason invoices get rejected.
7. The invoice date and the due date — both explicit dates, not just "NET 30."
8. Line items — description, quantity, rate, line total. Be specific: "Homepage redesign — 12 hours @ $150/hr" beats "Design work."
9. Subtotal, tax, and total — clearly separated. Show the tax rate.
10. Payment methods accepted — and a one-click pay link if you have one.
11. Notes / terms — late-fee clause, thank-you note, anything else.

What to leave off

Long disclaimers, your full terms-of-service, marketing copy. The invoice is a payment instrument, not a brochure. Keep it to one page.

Choosing an invoice number format

Sequential ("INV-001, INV-002") is simplest but signals how small you are. Date-based ("2026-05-001") is harder to read at a glance but looks more professional and gives you natural sortability.

For your first invoice, start at INV-1001 — not INV-001. It costs nothing and your client never knows they are your first customer.

Where freelancers usually get it wrong

• Vague line items. "Consulting" is not a line item. "Strategy session — Q2 planning (3 hours)" is.
• Missing PO number. If you were given one and you forget to add it, the invoice will be returned. Always ask for the PO before invoicing.
• Bank details only. ACH and bank transfer are slow and require the client to set you up as a new payee. Add a Stripe or PayPal link.
• No late-fee clause. Without it, you have no leverage when the invoice goes 30 days late. See the late-fee guide.

Free invoice template

Here is the minimum-viable professional invoice, in plain text. Copy, adapt, send.

INVOICE
Invoice #: INV-1001
Date: May 1, 2026
Due: May 15, 2026 (NET 14)

From:
Your Name / Studio Name
123 Your Street
City, State ZIP
your@email.com
EIN: 12-3456789

To:
Client Co., Inc.
Attn: Accounts Payable
ap@clientco.com
PO #: 778899

Items:
Homepage redesign — 12 hr @ $150/hr ........ $1,800
Logo refresh — 4 hr @ $150/hr ............... $600

Subtotal: $2,400
Tax (0%): $0
Total due: $2,400

Payment: Pay with credit card / ACH at [pay link]

Terms: Net 14. A late fee of 1.5%/month applies after the due date.

Or skip the manual format entirely: Duefy generates a professional invoice in 30 seconds, with PO field, tax ID, line items, one-click Stripe payment link, and an auto-applied late-fee clause.