How to write an invoice

An invoice is a formal request for payment. It tells a client what you did, what it costs, and how to pay you. Written clearly, it removes ambiguity and shortens the time between finishing work and receiving money. Written poorly, it sits in an inbox waiting for clarification.

Step 1 — Add your details and your client's

Start with your name or business name, email, and address. Then add the client you're billing, including a billing contact if you have one. Both sides need to be identifiable so the invoice passes accounts-payable without questions.

Step 2 — Give it a number and dates

Assign a unique invoice number (like INV-0001) and keep them sequential. Add the issue date and a due date. The issue date is when you sent it; the due date is when payment is expected.

Step 3 — List your line items

Describe each piece of work clearly, with a quantity and a rate. Vague entries like "services rendered" invite queries; "Brand identity design — 1 × €850" does not. The amount for each line is quantity × rate, and they add up to your subtotal.

Step 4 — Apply tax and discounts

If you're registered for tax, add your tax rate as a percentage. If you offered a discount, add that too. Discounts are applied first, then tax is calculated on the discounted amount. Keep both visible so the client can see how the final number was reached.

Step 5 — State your payment terms

Specify how and when you expect to be paid — for example Net 14 (due 14 days after the issue date) — and list your accepted payment methods. Clear terms set expectations and reduce late payments.

Required fields at a glance

Field	Why it matters
Your details	Tells the client who to pay.
Client details	Routes the invoice to the right department.
Invoice number	Unique reference for reconciliation and audit.
Issue & due dates	Set the payment window.
Line items	Itemised work with quantity and rate.
Total due	Subtotal, tax, and the final amount.
Payment terms	How and when to pay.

Common mistakes to avoid

• Reusing invoice numbers. Always use a unique, sequential number.
• Vague line items. Describe the work, don't just name a price.
• No due date. Without one, "someday" becomes the payment terms.
• Missing payment details. If the client doesn't know how to pay, they can't.

Write yours in the generator

Once you know what to include, the fastest way to produce a clean invoice is to fill in a template rather than build one from scratch. The generator handles the math, the currency formatting, and the print layout for you.