How do I make customer Order field mandatory?

There's no AR equivalent, you're reading it right. AR Preferences only offers Require Payment Reference on Entry, and that applies to Payments and Applications (AR302000) and Cash Sales (AR304000), not to invoices.

The only Require Customer Order Nbr. setting Acumatica ships sits on Order Types (SO201000), so it covers sales orders and never reaches an invoice you raise in AR or from project billing.

You can enforce it with a small customization, no code needed. In the Customization Project Editor, add a condition on the Conditions page (Type Equals Invoice, so credit memos don't get blocked), then on the Fields page set that condition as the Required property of the Customer Order Nbr. field (ARInvoice.InvoiceNbr). Do it at screen level. At DAC level it applies anywhere ARInvoice is used, including invoices generated by project billing and anything arriving through import scenarios or the API, and those will start failing to save.

If you bill through pro formas, PM307000 has its own Customer Order Nbr. box, so capture it there before you release.

On amending after release, there's no stock way. Once an invoice is released the only editable fields are the cash discount date and due date while it's open, so a credit memo is the only route today without further customization.

Hi ​@DeniseC ,

1. Making the Customer Order Field Mandatory

You are correct that while the AP module has a built-in "Require Vendor Ref." setting, the AR and Projects modules do not have an exact equivalent checkbox for the Customer Order Nbr out of the box.

Depending on how you generate your invoices, here is how you handle it:

• If you used Sales Orders (SO): There is a built-in feature. You can go to Order Types (SO201000), select your order type (e.g., SO), and check the Require Customer PO Number box on the General tab.
• For AR Invoices and Project Billing (Your Scenario): Because you are generating invoices directly from the AR or Projects modules, you will need a small Customization Project.
  • How it's done: You do not necessarily need a developer to write code. An administrator can use the Workflow Engine in the Customization Project Editor to set the CustomerOrderNbr field to "Required" for the AR Invoice screen. Alternatively, a quick DAC (Data Access Class) extension can append a [PXDefault] attribute to the field to force a value before saving.

2. Editing the Customer Reference After Release

In standard Acumatica, you cannot edit the Customer Order Nbr (or most other fields) once an invoice is released.

• Why? Once released, the invoice becomes a posted financial record. Acumatica locks the document to maintain strict audit trails and data integrity.

Hope above helps!!

​@DeniseC   You can make the Customer Order/PO Number mandatory by adding a validation through a Customization rather than relying on a standard Accounts Receivable preference.

If invoices are being generated from the Projects module, I would recommend validating the customer reference when the AR invoice is created/released, so the requirement is enforced regardless of where the invoice originates.

Regarding corrections after release, the standard behavior generally doesn't allow the customer reference to be freely changed on a released AR invoice. If the requirement is only to correct the PO/customer reference without affecting the financial transaction, this could potentially be handled through a customization, depending on the specific field and business requirements.

I’d first check whether the Customer Order field is required at the time of invoice creation in your version, and if not, a small customization should be able to enforce it.