What is a purchase order and do I need one for freelance invoices?

A purchase order (PO) is a number the client's procurement or finance team generates to authorize a spend. Many larger companies can't process an invoice without one — their accounting systems reject it. Before invoicing a company for the first time, ask: 'Do you need a PO number on the invoice?' If yes, get it before starting work to avoid two to four weeks of retroactive delay.

What payment terms should I use as a freelancer?

Net 14 (14 days from invoice date) is the standard for most freelance work. Net 30 is acceptable for large companies with fixed payment cycles. Include a late interest clause — typically 1.5% per month — directly on the invoice. Its presence signals that you track payment dates, which discourages casual lateness without requiring enforcement.

Should I invoice at the end of the month or when work is completed?

When work is completed, not at month end. Work delivered on the 3rd invoiced on the 31st adds up to 28 days of unnecessary delay before the payment clock even starts. Invoice on delivery. Your cash flow improves and clients pay for work that's fresh in their mind.

What to include on a freelance invoice

Q: What must be included on a freelance invoice?

At minimum: your legal name and address, invoice number, issue date, due date, client's full legal name and billing address, line items with specific descriptions, subtotal, VAT if applicable, total, and payment instructions (bank details or payment link). Missing any of these fields creates reasons for accounts departments to delay payment.

Q: How do I get freelance invoices paid faster?

Three things make the biggest difference: put your bank transfer details or payment link directly on the invoice (not just in the email), set an explicit due date rather than 'net 14', and ask for a purchase order number before starting work with any corporate client. These three steps remove the most common reasons for payment delays.

Invoice queries are the number one cause of payment delays, and most of them are preventable.

A missing PO number. A vague line item. No bank details. Payment instructions buried in a PDF that accounts departments have to scroll to find. These aren’t the client’s fault — they’re the invoice’s fault. A good invoice removes every reason to delay.

The non-negotiable fields

Your legal name or company name. Not your trading name if it doesn’t match your bank account — that creates confusion in accounts departments.

Your address and contact details. Required in most jurisdictions for valid invoicing.

Invoice number. Sequential. Every invoice you send needs one. Accounts departments track them. “Invoice” with no number gets lost.

Issue date and due date. Both, explicitly. “Net 14” means nothing without a start date to count from. “Due: 15 March 2026” is unambiguous.

Client’s full legal name and billing address. Not the contact person’s name — the entity that’s paying.

Line items: specific beats vague

“Website project — €4,500” will get a query. “Homepage redesign — discovery, wireframes, 3 design concepts, 2 revision rounds — €4,500” won’t.

Specificity serves two purposes. It makes the invoice self-explanatory to someone in accounts who wasn’t in any of your meetings. And it creates a record of what was delivered, which matters if a dispute arises later.

Break larger projects into phases or deliverables if it makes the invoice clearer. Don’t use generic descriptions that require the client to go back through emails to understand what they’re paying for.

The field most people forget

Payment instructions, directly on the invoice.

Bank transfer details — IBAN, BIC, account name — or a payment link if you use one. Not in the email body. On the invoice itself, clearly visible, ideally near the total.

Accounts departments process invoices in bulk, often without the original email. An invoice with no payment details requires them to contact you to ask. That contact takes two to five working days in most companies. Add that to the payment terms and you’ve lost a week before payment even starts.

If you use a payment platform, include the link. If you accept bank transfer, include the details. Make it impossible for someone to want to pay and not know how.

The purchase order problem

Many larger companies can’t process an invoice without a purchase order number. Their accounting systems reject invoices without it.

Before invoicing a company for the first time, ask: “Do you need a PO number on the invoice?” If yes, get the number before you start the work. Chasing it after you’ve invoiced adds two to four weeks of delay while the client’s procurement team generates the PO retroactively.

One question at the start of an engagement prevents the most common corporate payment delay. There’s more to it with corporate clients — the full picture on purchase orders and how to navigate corporate billing is worth reading before you take on a company as a client.

Late interest and payment terms

State your payment terms and the late interest rate explicitly on the invoice. Not in the contract alone — on the invoice as well, where the person approving payment will actually see it.

“Payment due within 14 days. Late payments accrue interest at 1.5% per month.” That clause doesn’t need to be enforced to work. Its presence signals that you track payment dates and that delay has a cost.

The terms work better when the client agreed to them in writing before the work started, not when they first see them on an invoice. How to set payment terms that clients actually respect covers the contract side of this.

Send invoices at completion, not at month end

Month-end invoicing adds a delay of up to 30 days to projects that finished early in the month. Work completed on the 3rd gets invoiced on the 31st, paid 14 to 30 days after that. The invoice was ready on the 3rd.

Invoice when the work is done. If you deliver a project on the 11th, send the invoice on the 11th. Cash flow improves, and the client pays for work that’s fresh in their mind rather than a month old.

Frequently asked questions

What must be included on a freelance invoice? Your legal name and address, invoice number, issue date, due date, client’s full legal name and billing address, specific line item descriptions, subtotal, VAT if applicable, total, and payment instructions directly on the invoice. Every missing field is a reason for accounts departments to delay payment.

How do I get invoices paid faster? Put your bank details or payment link directly on the invoice (not just in the email body), set an explicit due date rather than “net 14,” and ask for a purchase order number before starting work with any corporate client. These three steps remove the most common causes of delay.

What is a purchase order and do I need one? A PO is a number generated by the client’s procurement team to authorize a spend. Many larger companies can’t process an invoice without it — their systems reject it. Ask before starting work: “Do you need a PO number on the invoice?” Getting it retroactively adds two to four weeks of delay.

Should I invoice at month end or on delivery? On delivery. Work delivered on the 3rd invoiced on the 31st adds 28 unnecessary days before the payment clock even starts. Invoice on completion and your cash flow improves immediately.

Timescanner generates a billing report from your calendar at month end — hours by client, dates, period — so you always have the data to invoice accurately and immediately. Works with any iCal-compatible calendar.

What to include on a freelance invoice (so clients actually pay it)