## Documentation Index

Access the complete documentation index at:
https://www.zoho.com/uk/books/kb/llms.txt

Use this file to discover all available documentation pages before proceeding.

[Back](./)

# How do I auto-populate the “Sales Order Number” or “Sales Order Reference Number” from a sales order to an invoice?

The **Order Number** field, in Zoho Books, is an optional field on the invoice creation page. While [converting a sales order into an invoice](https://www.zoho.com/in/books/help/sales-order/convert-to-invoice.html), Zoho Books auto-populates the **Order Number** field with the value of **Sales Order Number** by default. If necessary, you can change this preference to auto-populate the value of **Sales Order Reference Number**. Here’s how:

1.  Go to **Settings** by clicking the **Gear** icon in the top right corner.
2.  Click **Invoices** under _Sales_.
3.  Choose the option **Use Sales Order Number** or **Use Sales Order Reference Number** under _Invoice Order Number_.
4.  Click **Save**.

![Invoice Order Number preference in Zoho Books](/books/kb/images/sales-order/zb/invoice-order-number-preference.png)

Now, whenever you convert a sales order into an invoice, the **Invoice Order Number** field in the invoice will be auto-populated with the **Sales Order Number** or **Sales Order Reference Number**.

* * *