When you push a purchase order from Inventory Planner to QuickBooks Online or QuickBooks Desktop, Inventory Planner creates an identical PO with the same products, quantities, cost that you see on the PO dashboard side. 

Before saving a PO you need to make sure that all products are created in QuickBooks. Otherwise you will get an error - Inventory Planner doesn't create products in QuickBooks automatically.

Go to Account > Settings 

> Purchase Orders and you can enable saving POs to Quickbooks.

Then after you've created a new purchase order, you'll see the option to Save to QuickBooks.

Select a supplier and the status of the PO when it saves to QuickBooks.

Note that any errors with saving the PO to QuickBooks will be shown at the top of your purchase order page.

Note: If you receive an error that the purchase order cannot be sent to QuickBooks Online, be sure to enable purchase orders within your QuickBooks Online account. 

If you've made changes to a purchase order and want those to reflect in your QuickBooks Online account, click "Save to QuickBooks" at the bottom of your purchase order. Changes will immediately sync to your QuickBooks account and will overwrite the prior PO information.

When you push a PO to your QuickBooks Online account, the following fields are updated: