Invorest
← All guides

What to include on a professional invoice

Updated 2026-06-18

A clear, complete invoice isn’t just a “request for money” — it’s a tool that helps the other side pay quickly and reduces back-and-forth. Leave off one key detail and, at best, the client keeps checking and slows payment down; at worst, you have no basis to claim a late fee when it’s overdue. Here’s the full checklist.

The essentials

These are non-negotiable:

  • The word “Invoice” and a unique invoice number (e.g. INV-0001) for tracking and reconciliation.
  • Your details: name / company, contact, address.
  • Client details: name, contact, address.
  • Issue date and due date — write a specific date, not “within 30 days”.
  • Line items: each product / service, quantity, unit price, amount.
  • Totals: subtotal, tax, total due.
  • Payment method: bank account, payment link or other — the easier, the faster you’re paid.

Bonus elements that get you paid on time

Not required, but they noticeably improve your odds:

  • Payment terms: late-payment rate, late fee, payment deadline. Spell them out and you have a basis to claim when overdue — see are late fees legal.
  • Purchase order (PO) number: often a precondition for payment in larger companies’ finance processes.
  • A polite note: e.g. “Thanks for your business — please pay by the due date.”
  • Tax / billing info: needed when the client claims it back or deducts it.

Common omissions

  • A vague due date like “ASAP” or “within 30 days” — leaving room to stall.
  • A missing invoice number, so neither side can agree which invoice you’re chasing.
  • No payment method, so the client “would pay, but has to ask for your account first”.
  • No late-payment terms, so you find you have no basis to claim when it’s actually overdue.

Don’t start from a blank page

Laying all of this out by hand takes time. The invoice generator already includes the must-have fields: fill in, preview live, export a PDF — free and watermark-free.

Once the invoice is sent, the real challenge is getting it paid on time — which is where Duefy shines: it tracks every invoice and chases overdue ones automatically.