What Goes on an Invoice (and How to Follow Up When It Isn't Paid)

An invoice does two jobs: it tells the client exactly what to pay and by when, and it creates a paper trail you can lean on if they don't. Most late payments trace back to an invoice that made the client's accounts-payable process work harder than it had to — a missing PO number, an ambiguous due date, no clear way to pay. Getting the document right is the cheapest collections strategy there is.

What every invoice should include

The word "Invoice" stated plainly at the top, and a unique invoice number — sequential numbering (INV-0041, INV-0042…) keeps your records auditable and gives both sides an unambiguous reference for every conversation about it. Then: your business name and contact details (and tax ID where applicable), the client's name and billing address, the issue date and an explicit due date — "Due August 28, 2026" is harder to misread than "Net 30." The body is an itemized list: description, quantity, unit price, and line total for each item, then subtotal, any tax or discount, and the total amount due with its currency. Finish with how to pay — the exact bank details, payment link, or accepted methods — and any late-payment terms you intend to enforce. Requirements vary by country and industry (VAT jurisdictions, for instance, mandate specific fields), so check the rules that apply to you; this is general information, not legal or tax advice.

Payment terms that actually get you paid

Net 30 means payment is due 30 days from the invoice date; Net 15 and Net 60 follow the same pattern, and "Due on receipt" means immediately. Shorter terms get paid faster for the unexciting reason that they enter the client's payment run sooner — if your work is delivered and accepted, Net 15 is a perfectly professional ask for small businesses. Two terms worth knowing: "2/10 Net 30" offers a 2% discount for paying within 10 days, and a late fee clause (commonly 1–1.5% per month where local law allows it) mostly works as a nudge — but only if it was agreed in your contract before the work, not invented on the invoice afterward.

When the due date passes: a calm escalation path

Most overdue invoices are process failures, not refusals — the invoice went to the wrong inbox, approval stalled, the payment run happens on the 15th. Escalate accordingly. Day 1–3 overdue: a short, friendly note with the invoice reattached: "Just checking this reached you — happy to resend or answer questions." One week: a firmer follow-up naming the amount, invoice number, and original due date, and asking directly for a payment date. Two to three weeks: a phone call — email is easy to defer; a person on the phone usually gets a real answer — followed by an email summarizing what was agreed. 30+ days: a formal reminder stating any contractual late fee and noting that work pauses until the account is current. Pausing new work is the most effective leverage most freelancers have, and it's entirely professional when your contract says so. Beyond that lie demand letters, small-claims court, or collections — rarely worth it below a few thousand dollars, which is why the contract, the deposit, and the clean invoice up front matter more than any recovery tactic.

Keep every message factual and polite: assume the mix-up, reference the invoice number, make the next step easy. The paper trail you're building is also the evidence you'd rely on if it ever did go further.

The free Invoice Generator produces a clean, itemized invoice with sequential numbering and printable output — and everything you type stays on your device.

Try it yourself

This guide pairs with the free Invoice Generator — no sign-up, runs in your browser, and shows its formula.