The nine things a complete invoice contains
There is no single universal legal format for an invoice. But the tax authorities in most jurisdictions (IRS in the US, HMRC in the UK, CRA in Canada, ATO in Australia, the EU's VAT directive) converge on roughly the same nine items. If yours includes all of them in plain English, no client's accounts payable team will ever come back saying they cannot process it.
1. The word "Invoice"
Top of the page, in title case. This sounds obvious, and yet I have personally received PDFs that look like invoices and never use the word once. They get filed as quotes or estimates by busy AP clerks and they sit there for weeks. Do not make anyone guess what the document is.
2. A unique invoice number
Every invoice needs its own number and the sequence has to be unbroken. The reason is dull but important: tax authorities check that you cannot hide an invoice by skipping its number. The simplest scheme is straight sequential, like INV-0001 then INV-0002 and so on. Some people prefix by year (2026-001) or by client (ACME-001). Both are fine as long as no number is ever reused or skipped. If you have to void an invoice, mark it VOID rather than reusing the number. The full longer story on this is in the invoice numbering guide.
3. Your name and contact information
Your legal name (or your registered business name), street address, email address, and phone number if you list one. If you operate as a registered company, include your company number and registered office. If your jurisdiction issues you a tax ID, a VAT number, a GST number, an EIN, an ABN, put it on every invoice. Missing tax IDs are one of the top reasons EU and UK clients legally refuse to pay until you reissue.
4. The client's name and contact info
The full legal name of the company or person you are billing, their billing address, and ideally a specific contact name (the person who hired you, or their AP contact if you have it). Generic addressees like "Accounts Payable" or "Billing Department" cause delays. Your invoice sits in a shared inbox watched by nobody in particular.
If goods or services were delivered to a different address, include a separate Ship to section. Several people who use the tool need this for cross-border shipments where customs needs the delivery address on the commercial invoice.
5. Issue date and due date
The issue date is the date you are sending the invoice, not the date the work happened. The due date is the calendar date payment is expected.
Do not write "Due in 30 days". Your client's billing software wants an absolute date. If your terms are Net 30 and the invoice issues on 5 March, write "Due 4 April". For more on what Net X actually obligates, the payment terms guide digs in.
6. A purchase order or reference number, if applicable
For corporate clients this is non-optional. Their AP system will reject any invoice missing the PO. Ask up front, every time. Every PO has a number; getting it onto the invoice before you send saves you a two-week round trip later.
7. An itemised list of what was sold
This is the part that actually determines how fast you get paid. For each line include four columns:
- Description. Specific, scannable. "Logo design, 6 hours" beats "Design services". If the work attached to a project, name the project.
- Quantity. Hours, units, or simply 1 for a flat-fee deliverable. Decimals are fine for partial hours.
- Rate. The per-unit price.
- Amount. Quantity times rate, auto-calculated by any decent tool.
One uncomfortable truth: vague invoices invite negotiation. A client who can see exactly what they are paying for, line by line, rarely disputes the total. A client looking at "Consulting services, $4,800" with no detail finds room to push back. I have watched a $5,000 invoice get whittled down to $3,800 over a vague line item once. Never made that mistake again.
8. Subtotal, adjustments, total
Show your math:
- Subtotal (sum of line items)
- Discount, if any (percent or flat)
- Tax with the rate clearly named, like "VAT 20%" or "Sales tax 8.25%"
- Shipping or expenses, if separately billed
- Total, in a larger font, the answer to "what do I owe"
- Amount paid (if a deposit was already received)
- Balance due, the actual amount owed now
If you operate in a country with multiple tax rates (UK VAT, GST in Canada or Australia, sales tax in the US), show each rate as its own line. Do not bundle them together.
9. How to pay you
This is the field most freelancers underdo. The easier you make payment, the faster it happens. Include whichever of these apply:
- Bank account name, account number, routing or SWIFT or IBAN as appropriate
- PayPal email or Payment Link
- Wise, Revolut, or Payoneer details
- A Stripe checkout URL
- A pay-now link if you have one
Put the most-used option first. Do not present three or four equally weighted choices; choice creates friction. If your preferred method is Stripe, lead with the link and put the bank details underneath in smaller text for the people who prefer wires.
The optional fields worth including
Notes. A one-line thank-you, or a heads-up about anything unusual on this invoice. Keeps the relationship warm and answers the "why is this different" question before it gets asked.
Terms. Your late-fee policy ("1.5% per month on overdue balances"), early-payment discount ("2% if paid within 10 days"), or anything contract-specific that needs to be visible at payment time.
Five mistakes that delay payment
1. Sending the invoice at month-end. Most AP departments process invoices on a weekly or fortnightly cycle. An invoice that lands on the 30th can miss two cycles. Send the day the work is complete.
2. PDF named invoice.pdf. Use a specific filename like invoice-INV0042-2026-05-13.pdf. It survives the client's downloads folder and turns up cleanly in search.
3. Asking the client to reply with their remittance details. You do not need remittance details to get paid in 2026. Drop the line; it slows things down.
4. Including a discount field with $0 in it. The client sees the word Discount and asks for one. Do not show empty fields.
5. Forgetting to update the invoice number. Every invoicing tool has caught me doing this at least once. Two invoices with the same number cause real bookkeeping headaches. Use a tool that auto-increments and double-check before sending.
What to do if the client does not pay
Send a polite reminder one day after the due date. Most overdue invoices are forgotten, not refused. If you do not hear back inside a week, send a firmer reminder that references the original. After three weeks, pick up the phone, or, if the relationship has soured beyond rescue, forward the matter to a collections service. Most legitimate clients pay long before any of that if you stay calm, professional and persistent. Full templates for each stage of the follow-up are in the following-up guide.
A 60-second invoice
Open the free invoice generator. Fill in From, Bill to, one line item, and the total takes care of itself. Pick your currency. Click Download PDF. The whole thing should take less than a minute. The PDF has no watermark and no upsell line on it. You are done.