How to create a professional invoice

Written by Adrian Simpson, who has sent a lot of invoices over 20+ years of running small web and IT businesses, and had more than a few sent back for missing something. Published 2 Aug 2026, updated 14 Aug 2026.

An invoice has one job: give someone every reason to pay it and no reason to put it aside. Most unpaid invoices aren't disputes. They're invoices missing a detail that stopped somebody processing them.

What every invoice needs

Nine things. Miss one of the first five and you'll get an email back asking for it, which costs you a week.

Invoice numbers

Number them in sequence and never reuse one. Sequential numbering is what lets you and your accountant spot a missing invoice, and in most countries it's expected for tax records.

A plain running number works fine. So does a dated format like 2026-014, or a client prefix like ACME-007 if you'd rather see at a glance who an invoice belongs to. What you want to avoid is anything random, and anything that restarts at 1 partway through a year.

The two dates

The invoice date is when you issued it. The due date is when you want the money. Both belong on the invoice, and the due date should be an actual date rather than a term.

"Net 30" makes the reader work out a date before they can act. "Payment due 1 September 2026" doesn't. More on choosing the term in the payment terms guide.

Line items that survive a query

This is where invoices get stuck. "Consulting, $2,400" gives the person approving it nothing to check against. They'll park it and ask you what it covers, and now you're two weeks out.

Write each line so somebody who wasn't in the room can match it to work that happened.

If the job ran against a purchase order or a signed quote, put that reference on the invoice too. In a company with an approvals process, a PO number is often the difference between paid this month and paid next.

Tax, discounts, and the total

Show the subtotal, then any discount, then tax, then the total. The order matters because discount comes off before tax is worked out, and a client who checks your arithmetic and gets a different answer will ask you to reissue.

If you charge sales tax or VAT, show the rate and the amount as separate lines rather than folding it into the total. Registered clients need that split to reclaim it. The sales tax calculator handles the discount and shipping order for you.

How to pay you

Put the payment details on the invoice itself, not in the email. Emails get forwarded to accounts departments and the message body gets lost on the way. Bank details, a payment link, or both.

Also worth naming who to contact with a question. An invoice with a name and a phone number on it gets queried. One without gets ignored.

Deposits and part payments

Long jobs shouldn't wait until the end for money to move. Invoice a deposit before you start, then bill the rest at agreed points, and say on each invoice how it fits the whole.

The bit people get wrong is not showing the running total. An invoice for $2,000 with no context looks like a $2,000 job to whoever is approving it. Spell it out: "Deposit invoice, 40% of $5,000 agreed 12 July. Balance of $3,000 due on completion." Now the number has a story and nobody has to ring you to confirm it.

Do the same on the final invoice. Show the full price, subtract what's already been paid, and put the remaining balance as the amount due. Clients pay the number in the big box at the bottom, so that number has to be what you actually want.

Fixing an invoice you've already sent

Wrong amount, wrong client, wrong tax rate. It happens. The rule is that you don't quietly edit an invoice that's already gone out, even if you're certain nobody has looked at it yet.

Once an invoice is issued it's a record, and their accounts system may already have it. Two copies of invoice 2026-014 with different totals is the kind of thing that stalls a payment for a month while two people try to work out which is real.

For a small fix caught within minutes, an email saying "please ignore invoice 014, replaced by 015" usually does. Anything that's been in their system overnight, or anything involving tax, gets the credit note.

Invoicing a client in another country

Cross-border invoices need a few things a domestic one doesn't, and missing them is a slow way to get paid.

Name the currency next to every figure, not just once at the top. "$4,500" means different money in four countries, and USD, CAD, and AUD have all been assumed wrongly on invoices before. Write USD 4,500 and the ambiguity is gone.

Say who covers the transfer fees. International payments lose $15 to $50 in the middle, and if you don't say, that comes out of your side and your invoice arrives short. One line saying all bank charges are the payer's responsibility fixes it.

Include whatever the receiving bank needs, which usually means IBAN and SWIFT or BIC rather than a domestic account number. And check whether tax applies at all. Plenty of cross-border business services are zero-rated or fall to the buyer under a reverse charge, in which case the invoice needs a note saying so. The rules depend on both countries, so confirm yours rather than guessing.

How long to keep them

Longer than feels necessary. Most tax authorities want somewhere between five and seven years, and the clock often runs from the end of the tax year rather than the invoice date. Keep them as PDFs somewhere backed up, and keep the ones that were never paid too, because a written-off debt still has to be evidenced.

The five things people leave off

In rough order of how often it happens: the due date, the PO or quote reference, the tax breakdown, a contact name, and the invoice number. Every one of them is a reason for somebody to do nothing.

Make one now

The invoice generator has fields for all of it and downloads a PDF, with nothing stored anywhere. Before you send, run through the invoice checklist.

This is general guidance, not legal, tax, or accounting advice. Invoicing rules vary by country and change over time, so check yours with a qualified professional before it matters.