Can you put in a order number with the start plan?

Hello there, Booy

Thanks for checking in with us. I'll share some information about how you can add a purchase order (PO) number to your invoice in QuickBooks Online (QBO).

The ability to create custom fields on an invoice template is only available on the Plus, Essentials, or Advanced versions of QuickBooks Online. If you're using Simple Start, please note this option is unavailable. 

I recommend upgrading your plan from Simple Start to Essentials to take advantage of this feature. I'll show you how.

1. Sign to QuickBooks Online as primary or company admin.
2. Go to Settings ⚙, then Account and Settings.
3. Select the Billing & Subscription tab.
4. Ensure your payment info is current.
5. In the QuickBooks Online section, click Upgrade your plan.
6. Review the available plans and then select Choose Plan.
7. Follow the on-screen steps to upgrade your plan.

I'm adding this article for additional insight about adding custom fields: How to add custom fields to invoices.

Let me know if you have any questions about adding purchase orders in QuickBooks. I'll be waiting for an answer from you. Have a wonderful day.