How to write a professional invoice
A good invoice does two jobs: it tells your client exactly what to pay, and it creates a paper trail that protects you if payment is late. Every invoice you send should include your business name and contact details, your client’s name, a unique invoice number, the issue date, a clear due date, itemized line items with quantities and rates, and the total amount due including any tax or discounts.
Number your invoices so you stay organized
Use one sequential series (INV-0001, INV-0002, …) and never reuse or skip numbers. Sequential numbering makes bookkeeping simple, helps your accountant reconcile payments, and looks professional to clients and tax authorities alike.
Set payment terms that get you paid on time
State the due date on every invoice — “due within 14 days” beats “due upon receipt” because it removes ambiguity. For larger projects, ask for a deposit upfront and milestone payments as work progresses. If a client pays late, a polite reminder referencing the invoice number and due date resolves most cases without friction.
Keep copies for your records
Save every invoice as a PDF with a consistent filename, for example INV-0001-acme-corp.pdf. Most countries require you to keep business records for several years, and clean archives make tax season dramatically less painful.