Customer purchase order missing? Check the invoice process

Establish what the customer actually needs

Ask whether the customer uses a purchase order for this job, which reference belongs to it and where that reference needs to appear. They may want it on the invoice document, in the submission email or in a portal field. Check their answer before changing anything.

This is an operational check of the customer’s process, not a claim that every invoice legally requires a purchase order. If there is a disagreement about the agreement itself, treat that as a separate issue rather than assuming a missing field resolves it.

The Small Business Commissioner advises requesting a required purchase order early and identifying who receives invoices. That narrow check can be built into your project setup, before you reach the payment chase.

Ask the person who can supply the reference

Your project contact and the accounts contact may have different responsibilities. Ask the project contact who raises the order, then confirm with accounts how they match it to an invoice. Keep both names beside the job so the request does not keep circulating between inboxes.

• Which job, quote or milestone does the order cover?
• Who can provide or confirm the exact reference?
• Does the customer need any information from you to raise it?
• Where should the completed invoice be submitted?

Give enough context to identify the work, but keep the question focused. Ask for the next action and the person responsible, rather than sending a general complaint about unpaid invoices.

Subject: Reference needed for [job / invoice number]

Hi [known project contact],

Accounts has asked for a purchase order reference for [specific job]. Could you confirm the exact reference, or who can supply it?

Please also confirm whether it covers [this visit / milestone] and where accounts needs it shown. If you need information from me to raise the order, please name that information.

Thank you,
[name]

Record the gap without inventing a number

In your internal notes, write “PO awaiting customer confirmation” and record the request date. Do not place a guess, an unrelated order or a placeholder into the customer-facing reference field. An apparently complete invoice with the wrong reference can create another round of queries.

When a reference arrives, compare it with the customer’s written confirmation, including letters, numbers and punctuation. Check that it refers to the correct business and job. If the reference covers several milestones, ask which part applies to this invoice rather than assuming the whole project amount is approved.

Keep the earlier submission and the new confirmation in your records. They explain why you are sending an updated copy and prevent the invoice history from becoming a set of unexplained replacements.

Fictional example: a £780 invoice held for a reference

Leah sends INV-602 for £780 of agreed maintenance work. Accounts replies that the job needs its purchase order reference. Leah asks the site contact to identify the relevant order and asks accounts whether an updated document is needed.

The site contact confirms PO-M44-18 in writing. Leah checks that it covers this maintenance visit, follows her normal invoice correction process and sends the requested version through the agreed route. Her note records the reference, submission date and accounts acknowledgement.

Leah then asks whether the invoice can now be processed and when accounts expects payment. She does not present the reference arriving as payment confirmation, create a second demand for the same work or quietly change the agreed due date.

Resume follow-up from the latest information

Before resuming reminders, check that the current invoice details, reference and recipient match the version sent to accounts. If reminder content has changed, review the affected messages again. Ask one specific processing question instead of replaying the earlier chase unchanged.

For the next job, record three items before invoicing: reference owner, confirmed reference or explicit “not used”, and submission route. Leave “not yet confirmed” visible where applicable. A blank field should prompt a check, rather than invite someone to reuse the previous job’s order.