> For the complete documentation index, see [llms.txt](https://support.ordereazi.com/central/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.ordereazi.com/central/order-management/settings/organization-setup/system-settings/customer-order-number-options.md).

# Customer order number options

Require a customer order number before approval, show the customer's own reference, and warn about duplicate order numbers.

Many clients won't pay an invoice that doesn't quote their purchase order number. The **Customer Order Numbers** settings in System Settings can make the number required before an order is approved, and warn you when the same number is used twice.

Two fields are involved:

* **Customer Order Number:** Your client's purchase order number, entered by your team.
* **Customer Order Reference:** A reference from the client's side, set by the client or an integration, such as with an online order.

### Before you start

You'll need the **Organization Setup** permission, in the **Settings** permission group.

### How to change your customer order number options

1. In the main menu, go to **Settings** > **Organization Setup**.
2. Select the **Configuration** tab.
3. Under **Customer Order Numbers**, change the settings you need.
4. Select **Save**.

You see "System Settings saved successfully".

### The settings

| Setting                                        | What it does                                                                                                                                |
| ---------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| **Require Customer Order Number**              | A project needs a customer order number before its order can be approved.                                                                   |
| **Check Duplicate Customer Order Number**      | Shows a warning when a customer order number has already been used on another project.                                                      |
| **Duplicate Customer Order Number Per Client** | Only warns when the number was used on another project for the same client. Shown once **Check Duplicate Customer Order Number** is ticked. |
| **Show Customer Order Reference**              | Shows the **Customer Order Reference** field on projects.                                                                                   |
| **Allow Customer Order Reference Edits**       | Lets sales reps change the **Customer Order Reference** on a project. When it's off, the field can only be read.                            |

**Example:** Two of your clients both use simple order numbers, such as "PO100". You tick **Check Duplicate Customer Order Number** and **Duplicate Customer Order Number Per Client**. A rep enters "PO100" for the second client, and there's no warning. When the rep enters "PO100" again for the first client, a warning shows that the number is already used, so the rep can check for a duplicate order.

If a project has no customer order number when someone tries to approve the order, they see "Customer Order Number is required before approving an order." Enter the number on the project and approve it again.

### Related pages

* [System Settings](/central/order-management/settings/organization-setup/system-settings.md): the other settings groups
* [Quote approval options](/central/order-management/settings/organization-setup/system-settings/quote-approval-options.md): ask clients for their purchase order number when they approve a quote