How to write an invoice
Every field an invoice needs, in the order it should appear — plus the four mistakes that get one rejected by a client's accounts department.
An invoice is rejected far more often than it is disputed. The work is fine, the amount is agreed, and the document still comes back — because a field is missing, a name is wrong, or nobody can tell what it is for. This is the order to fill it in, and what to put in each part so it goes through first time.
Start with the header: who is asking
Your trading name, your address, and your tax registration number if you have one. If you are a registered company, add the registered name and company number — in many countries that is a legal requirement, and everywhere it is what lets the client's system identify you.
One rule that quietly causes delays: the name on the invoice should match the name on the bank account. A payment to "L. Bakhia" against an invoice from "Aria Studio LLC" gets held by anybody doing their job properly.
Then who is being asked
The client's legal entity — the registered company name and its registered address. Not the brand, not the office you visited, and not your contact's name.
This is the most common correctable error on a first invoice. An invoice addressed to a person cannot be entered as a company expense; an invoice addressed to a trading name that is not the registered entity cannot be reclaimed against in most tax systems. Ask for it once, in writing, and reuse it forever.
If they asked for a purchase order number or a cost-code reference, it goes here too. An invoice missing the reference it was raised against often cannot be matched to anything at all, and is rejected without being read.
The number and the two dates
A unique invoice number, continuing your sequence with no gaps — invoice numbers covers why the gaps matter and three schemes that work.
Then two dates, not one. The date issued, and the date payment is due. "Payment on receipt" and "at your earliest convenience" are not dates: an invoice with no due date cannot become overdue, which means it never enters anybody's chasing process — including your own.
Pick the terms deliberately. Net 14 and net 30 are both normal; net 30 is the default assumption in most of the world if you say nothing. Whatever you choose, write the actual date on the invoice rather than the number of days, so nobody has to calculate it.
The line items — where invoices actually get queried
One line for each thing you are charging for: description, quantity, unit price, line total.
The description is the part that decides whether somebody has to ask you a question. Write it for a reader who was not in the room and will read it in six weeks:
| Gets queried | Gets paid |
|---|---|
| Design work | Brand identity — logo, type and colour system |
| Consulting, August | Strategy consulting, 3 days, 12–14 August |
| Development | Checkout rebuild, phase 1 of 2 (see PO 4471) |
| Expenses | Travel to Kutaisi, 21 August — receipts attached |
Split by deliverable rather than by hour where you can. A single line reading "48 hours" invites a conversation about the 48 hours. Four lines naming four finished things invite none.
Tax, shown as its own line
The subtotal before tax, the rate, the tax amount, then the total. Never a single figure with tax folded into it — a buyer who cannot see the tax cannot reclaim it, and will ask you to reissue.
If you are not registered for VAT or sales tax, say so briefly rather than leaving a blank where the tax line should be. A missing tax line reads as an omission; "Not VAT registered" reads as an answer.
Cross-border sales have their own rules — reverse charge, zero rating, place-of-supply tests — and they are worth checking once for the countries you actually sell to. Getting it wrong is not usually a rejection; it is a correction several months later.
The total, and how to be paid
The amount due, with the currency stated explicitly. "1,200" is ambiguous the moment two countries are involved; "1,200 GEL" is not.
Then the payment details: bank name, account name, account number, and the international identifiers if the payer is abroad. Put the invoice number where they will see it as the payment reference — it is what lets them match the payment, and what stops you being chased for something already paid.
Read the account number twice. It is the one field on the invoice where a typo does not bounce back to you.
What it looks like when it is right
Every rule above, on one page. This is the same invoice the generator on this site produces — not a mock-up of one:
Bank transfer · GE00TB0000000000000000 · reference INV-014
The four mistakes that get invoices sent back
- No invoice number, or a repeated one. Most systems refuse the document outright.
- The wrong entity in the client field. Cannot be entered, cannot be reclaimed.
- Tax not shown separately. Cannot be recovered by the buyer.
- A missing PO or reference number. Perfectly legal, and completely unmatchable.
All four are avoidable in the thirty seconds before you send, and all four cost weeks after.
Before you send it
Read the invoice as the person receiving it. Can they tell who you are, what this is for, what it costs, when it is due and how to pay it — without asking anybody? If any of those needs a follow-up email, fix it now.
Then send it to the person who actually pays, which is usually not the person who hired you. If you would rather not assemble any of this by hand, the free invoice generator writes it, calculates it and lays it out from one sentence.